• XANA was, and in fact, still is, unique among the majority of villains in the realm of pop culture is that he never personally appeared or communicated with anyone throughout the entire series, with the exception of five episodes at most, out of 97 total, meaning the viewers were just in the dark about it as the characters, in fact, to this day, audiences re-watching the series have a hard time pinning down XANA's motives. XANA is literally the result of a villain who is Nothing Is Scarier as a character. If this isn't enough convince you how terrifying he is, just read the rest of this page to see how much it is related to XANA. It's made even more eerie considering that unlike most villains, XANA has no face nor voice: It (or "he" as referenced by the cast, due to French grammar) simply uses actions to "speak", which basically is kill all humans for no other reason other than sadism.
  • His behavior aside, XANA is also a prime example of a Digital Abomination. Unlike most evil computer programs in fiction, XANA's attacks are rather… arcane in how they act. Through the usage of what is known as a Specter, a black ghost-like energy apparition XANA can do just about anything he wants or thinks of, only being limited by how much power he can use. Season 1 is perhaps the greatest example of this, as almost every attack he unleashes is some kind of natural disaster created from the simplest of things. Animating old samurai armor, making sinkholes, turning basic chemicals into sentient, deadly gas… the list goes on.
  • Then there's his power. XANA's other terrifying attribute is that he evolves in strength as the series progresses. Yes, his attacks from the first season are a showcase of XANA at his weakest or less intelligent levels. By the second season, it is revealed that the Return to the Past has been making XANA stronger every single time thanks to his connection to the supercomputer, and he starts possessing people, granting them all kinds of superhuman abilities and directly harming both the Lyoko Warriors and the people around them directly. Oh, and fun fact, he's also getting smarter, creating legitimate strategies that lead to perhaps his closest victories… and then in the Season 2 finale, he gets out of Lyoko, as one of these strategies enables him to escape into the network with a program that makes him even more powerful. Suffice to say, Seasons 3 & 4 became a complete uphill battle for the Lyoko Warriors, as the former had him gain more consistent victories with even stronger attacks and bigger monster armies, while the latter confirms that he's just about this close to unleashing an army of real-life robots and cyborgs thanks to facilities he's taken over all over the world.
  • The one thing often understated about XANA? How he learns, and takes NOTHING for granted. Unlike most electronic based villains who have very little understanding of love or heroic traits, XANA does not have a bias against either. "Ghost Channel", a Season 1 Episode mind you, is the only time we see XANA have a blind spot for how a person would react, underestimating Jeremie's resolve to enter Lyoko to save his friends. Even ignoring that, in a short amount of time he had all but perfectly emulated how Kadic Academy runs and how its inhabitants interact with each other and the Lyoko Warriors. He had been observing all that time, carefully. As for that blind spot? He never has it again and knows exactly where to twist the knife to have the Lyoko Warriors move in a way that benefits him. "XANA's Kiss" is a near masterclass, where he understands the protagonists enough that he spends that entire episode screwing with them just by having Specters take certain forms and kiss the right people. He understands how his opposition acts completely, while it's still incredibly hard to get a read on XANA beyond his overarching goals for each season.
• The monsters XANA uses in Lyoko. Most of them are partially organic, partially mechanical. Kankrelats are small, cockroach-esque monsters with four mechanical legs on a round base and a single red robotic eye. Sounds unsettling out of context, but they're laughably stupid and often the comic relief of XANA's monsters. Others however are not. Here's a quick list of the more disturbing ones:
  • Bloks, unlike the Kankrelats, are as large as a person in height, and have four of the creepy Eyes of XANA on each side of their rocklike shell. Their weapons range from Frickin' Laser Beams to rings of flame to a freeze ray; in Season 1 more than a few Lyoko Warriors have been frozen solid by the Freeze Ray, unable to react to their friends being attacked and devirtualized.
  • By far the scariest of the standard monsters (we're not even getting into the Scyphozoa or the Kolossus, but be patient, we will.) is the Megatank. Unlike the other monsters which have a real life animal that they're based off of, the Megatanks are just alien. They're huge black bowling balls that split in half, revealing an Eye of XANA, metal framework, and squicky pink flesh connecting its halves. Most monsters use the aforementioned Frickin' Laser Beams, but the Megatank just shoots a plane of energy in a circular path; causing INSTANT devirtualization on a hit, and impossible to dodge if you're in its way, even if you're above the Megatank. That's not counting it simply flattening you as it rolls.
  • Then, there's the Tarantula, XANA's first new monster. XANA now has a four cannon-legged behemoth that moves very much like a spider. It wipes out the group in the season 2 premiere, and is one of the signs of XANA's power increasing, a plot point that would loom over the Lyoko Warriors' heads throughout all of Season 2.
  • NOW we get into the Scyphozoa, which is quite possibly put, XANA's most horrific monster and his Dragon for Seasons 2 and 3. Unlike his other monsters, the Scyphozoa is not designed to fight. Rather, it is meant to drain Aelita's memories to allow XANA access to the Keys of the Lyoko locked in her mind, which, if he manages to obtain, will enable him to escape the supercomputer and infect the world-wide web. It takes the form of a floating jellyfish, using its tentacles to subdue its victims and rip out their memories. Aelita is subjected to it numerous times throughout the series, as is Yumi in Episode 34, and from we can tell, the experience is NOT pleasant and involves draining the life of whomever gets caught by it in order to extract their data. To up the nightmares even further, if the thing catches you, you can't escape unless there's someone else nearby who can cut the tentacles. Worse, it cannot be destroyed by conventional ways, only made to retreat when its tentacles are severed. Through the entire run of the show, the only thing that managed to kill the Scyphozoa was Aelita overloading the Skid's barrier on season 4, and even then XANA just programmed another one.
    • And in Season 3? When you thought that with XANA's escape in the network means that it will never appear again? Surprise: it does. In fact, it turns out to have more functions than just data extraction. It can implant viruses in the Lyoko Warriors, viruses that XANA uses to mind control them. Yes, the Lyoko Warriors, who should be immune to XANA's mind control tactics in the virtual world, are no longer safe. Once again, Aelita is subjected to the process so XANA can have her delete the surface sectors so he can freely attack the Core of Lyoko. Then in the Season 3 finale… William, the Sixth Ranger, falls victim to the creature. He leads an army of Creepers against Lyoko's core, destroying it and ending up as XANA's commander for most of Season 4.
  • XANA-William. Now under XANA's control, William has been upgraded into a dark and powerful juggernaut leading XANA's forces on Lyoko. His expressions are unsettling, and much like his master, he rarely ever talks, except to grunt and yell… until later, when he starts taunting his former allies and openly threatening them with his demonically warped voice. He's extremely brutal in battle, to the point of the show needing to use a Gory Discretion Shot at times, which it has NEVER needed with XANA's other monsters.
    • Ditto his-admittedly awesome-leitmotif. As soon as those electric guitars start, you know the shit has hit the fan.
  • The monsters in the Digital Sea, partly due to them having very sharp teeth, or, in the Kalamar's case, a very big drill. Unlike XANA's other monsters, with whom devirtualization is just going back to the real world, a defeat via these creatures equals permanent deletion due to the nature of the Digital Sea.
  • Finally, there's the Kolossus. It's a gigantic lava golem that looks very much like an Eldritch Abomination. For reference, here it is◊. It only appears in three of the last four episodes of the series, but those three leave enough of an impact. It can destroy the Skidbladnir in one hit (and does), and it has two Eyes of XANA that need to be hit SIMULTANEOUSLY in order to destroy it. Note the size of the thing. It can hold Lyoko towers in its hand and instantly put them under XANA's control. Now you can run.
• Some of XANA's attacks do border on this, especially if it's a widespread offensive. XANA-possessed characters can be particularly creepy, and many examples of XANA trying to murder the protagonists (like electrocuting Jérémie) can induce nightmares.
• A lot of the crazed expressions XANAfied William makes, but, really, not just him actually, any XANAfied person will often wear an unsettling expression with Voice of the Legion to boot. Their specific behaviors and abilities likewise change from episode to episode, and this somehow just makes them creepier since it means that you don't know what kind of malignant personality or powers XANA is programming into these things whenever they pop up.
• Every member of the group has been badly electrocuted at least once by XANA. Everyone. And it's not Played for Laughs, ever. The side characters don't escape this either. Almost every single character in the show, if not all of them, have been harmed by XANA in some way, shape, or form.

• Before we hit the individual seasons, let's talk for a little bit about the initial version of Code Lyoko, known as Garage Kids. This promised to be significantly darker, and the promo◊ materials◊ certainly give off a morbid tone. Powers in the real world, and the blatant reveal of Franz Hopper's prototype incarnation as being actively malignant can certainly raise some alarm bells.
• The pilot itself certainly lives up to this darker tone. Each scene of virus activity from Xanadu is given a real sense of dread, and the rather unclear boundary concerning the virtual and real worlds creates a very unsettling atmosphere. The very first scene, taking place on a stormy night, has the silhouette of the virtual world of Xanadu appear on a computer screen, and Specters begin to emerge from it. Unlike their smoke-like appearance in the final product, these specters have a much more defined, shadowy form, and when they come out of said computer, they seem to pouring out of it like blood.
  • They aren't much better in the virtual world either. Instead of XANA using Specters to attack the real world and then having his monsters guard the Towers, these Specters seem to act freely in the virtual world just as they do in the real world, with a haunting hum as they move, only seeking to destroy any intruders after them. Ulrich has a very justified Oh, Crap! expression when he sees a whole swarm of these things◊ corrupting a Tower just before they all try to Zerg Rush him.
• Of course, in animation there's a lot of Art Evolution between pilot episodes and the resulting series themselves, but the pilot (in certain scenes) combines Off-Model and Unintentional Uncanny Valley in a creepy way. To clarify: Ulrich's avatar has eyes that seem like they came from the first Crash Bandicoot (1996).
  • The blue tint on Xanadu likewise helps to illustrate the creepy vibe. To be fair to the producers though, they originally wanted a crisper look, though this doesn't fully alleviate the above Uncanny Valley effect.
• XANA is bad enough since he doesn't have a body or singular form. Here, he's not even identified as a singular entity, giving off the impression that the virtual world itself is somehow sentient and generating monsters to want to attack the real world for whatever reason. Nothing Is Scarier is somehow even greater, topped with Yumi explaining that she, Ulrich, and Jeremie don't know why Xanadu was created, only that something is wrong with it.
• Ultimately, given how the show creators at the time were taking influence from Serial Experiments Lain (A series which is filled with nightmare fuel and whose head writer worked on Digimon Tamers, which has its own brand of horrors), one can start to understand where all the nightmare fuel on this page ultimately came from… and then wonder just how bad it could've gone had the pilot concept been used.

• Yumi temporarily dies in this episode where she falls into the Digital Sea in the climax where Ulrich arrived too late to save her. Had it not been for Aelita's kindness to offer up a chance of being materialized to Earth to bring Yumi back. Yumi would have died permanently in Lyoko! It really hammers in that as cool as the combat may be, there are legitimate risks to fighting in Lyoko.

• XANA's taken control of a Kill Sat.
• Yumi gets the closest any of the heroes had of being Killed Off for Real (next to Aelita who actually did die temporarily in the Season 2 finale), when XANA tries to use said satellite to fire on her, how close was she to being incinerated by the laser? A millisecond; had Jeremie and Aelita been a second late, Yumi would have been brutally murdered on the track field.^note Making matters worse was that the blast radius would've incinerated Odd as well as he was nearby Yumi's location

• Also known as the episode where XANA where took over a bunch of rats. They swarm all over the school, and of course it has to take place at night. Huge swarms of rats, all under XANA's control. Eugh…
  • On the subject of the rats in particular, the start of this episode deserves special mention. One little rat is minding its own business and doing its usual thing, scavenging for food. Suddenly, XANA's spectre pins the poor thing down and forces itself into the rat's mouth. And the kicker is that this is the first time we see XANA taking over a living being, just when everyone was used to him taking over inanimate objects. As if we needed more Paranoia Fuel…
    • And that's before getting into how XANA spreads his control to the rest of the rat colony. The result is basically a (thankfully rat only) zombie infection as the rat he first possessed bites one of the others and causes it to fall under his control too, with those two rats doing the same thing to the rest of their colony memebers offscreen soon after. Even worse is that this turned out to be Foreshadowing for one of XANA's later attacks, making this one, and the one the following episode, much more horrifying looking back on it.

• Had enough of the rats in the previous episode? Well here, XANA takes it up a notch by pulling the same trick on wasps. Soon after he starts spreading his influence on the colony of wasps, he not only ends up nearly stinging someone to death, but forces them to build their hives in all manner of places, including under the sewer grate the Lyoko Warriors use to get to the factory. Even if you don't hate or fear wasps, the aggressive and territorial behavior they exude thanks to XANA's control over them is still disturbing, especially with their nests.

• On paper, "Laughing Fit" sounds ridiculous with XANA using Laughing Gas to make anyone and everyone exposed laugh themselves into submission. Then your realize that unless they're somehow exposed to water? The victims can't stop laughing. Meaning eventually they'd all suffocate and die, something Yumi's parents see for themselves as Yumi is exposed to it. Jeremie is barely able to perform a "Return to the Past" before he gets exposed and starts laughing as well…

• Lord, this episode is absolutely nightmarish. Imagine an MP3 becoming a successful hit. Now imagine it being a simple, looped sentence (The original French version is “You should never ever dare! No!”) creepily reminiscent of synthethizeritis. Now picture it putting each of its listeners in a comatose state. It's especially terrifying when Odd falls victim to it, as he's stuck with a huge grin on his face, thus looking like he'd been murdered by The Joker. And not only does he go into a coma, but the attack is undone just as he flatlines…
• And because it's from XANA, of course he's finding ways to make it worse. By spreading it all over the city, hacking into every electronic device he can in order to force people to listen to it.

• The conflict of the episode: Jeremie, thinking he has upset Aelita after snapping at her the night before, tries to go to Lyoko to apologise. Besides the point that Jeremie is afraid of making that jump across worlds personally, he becomes stuck halfway and the other Warriors have to race to get him back to Earth before he's gone for good.
• Brief, but just after a Yumi eye catch about 3 and a half minutes in, there's an establishing shot of a corridor. We can see a male student cornering a female one by placing his arms either side of her, and she does not look comfortable at the situation.

• XANA using the Factory assembly lines to make his first robots to kill the Lyoko Warriors with. Never mind that there were enough spare parts lying around for him to make these things, look at their faces◊. Are they smiling? Is it XANA trying to imitate a skull? Whatever the case, they look creepy as hell.

• Think about it; the evil computer virus has taken control of FREAKIN GRAVITY to the point where it can just LAUNCH PEOPLE INTO ORBIT WITH EASE. Let's be thankful that this was still only XANA in Season 1.
• There's a moment of utter terror near the end, when Aelita seems to be trying to get to the Tower, drawing the Hornet's fire onto her. Jeremie, Odd, and Yumi are horrified, even moreso when it seems that Aelita has fallen into the Digital Sea, the Hornets after her. Thank god it was only a decoy.

• Let's admit it, "Ghost Channel" is the scariest episode of the series' first season and still stands out from other seasons due to the unique virtual phenomenon that only appears in one other episode. For a season with episodes that were mostly Filler and that involved XANA attacking and the team having to deactivate a tower in Lyoko (and that were pretty creepy on their own), it really drives home what kind of a threat this nutcase of a computerized Omnicidal Maniac is, to the point where his pants-browningly horrifying One-Winged Angel form at the climax now serves as the page image. Good Lord.
• Speaking of said page image, who shat bricks when we saw XANA's disguise of Jérémie breaking down from "Ghost Channel"? XANA Jérémie's "NOT LOGICAL! NOT LOGICAL!" after the kids decide that he's the fake Jérémie because he doesn't understand that Jérémie would virtualize himself to save his friends. And then the scene where he screams and then tries to kill the characters.
  XANA: NOT LOGICAL!!!! NOT LOGICAAAAAAAAAAAAAAAALLLL!!!!!! HAHAHAHAHAHAHAHAHAH! YOU ARE GOING TO DIE!!!
• Nothing Is Scarier when it comes to XANA's masterstroke. He tries to trick Ulrich, Yumi, and Odd into going into the Scanners, except they aren't going to be sent to Lyoko obviously (since they're already there), but rather, will be deleted once and for all. The idea that XANA had that level of power over them while in the Simulation Bubble and was slowly leading them to their deaths further demonstrates just how scary he was in this episode.
• The vibe and atmosphere in the episode bear mentioning. All of sudden, after what seems to be stopping a routine XANA attack, Jérémie learns that his friends have all vanished, and he doesn't know why. Yet we see them, clearly somewhere, yet things seem off from their perspective. It's incredibly creepy, and really stands out in an otherwise fairly formulaic season.
• The most terrifying thing about this episode? This was the only time XANA ever personally appeared (albeit operating behind the form of the zombie-like Jérémie Evil Doppelgänger), so we actually see that yes, he does take pleasure in the misery he causes.
  • We also finally learn what he thinks of the Lyoko Warriors. Obstacles. They're obstacles, in the way of his horrible designs for humanity. It's such a cold, precise line that we might expect from a rogue Artificial Intelligence… which makes his total breakdown above even worse.
    XANA: Watching Jeremie run from the zombie-looking Nicholas and Herve Soon I won't have any more obstacles.

• Also known as the first time XANA ever materialized his monsters into the real world, and we start to see the kind of damage they can do in real life. Granted, XANA only started out by sending Kankrelats, thank goodness… Yeah, as it turns out, their lasers are able to punch through walls and leave burn marks on anyone hit by them. And since this is in the real world, they're fully capable of killing you.
  • Aelita likewise brings up what might happen if the attack goes on: XANA figuring out how to send his other monsters into the real world as well. The Kankrelats are bad enough, but what about the Bloks? Krabs, Hornets? Megatanks?

• We talked about the Tarantula earlier. Fun fact, this is its debut episode, and a sign of how tough the battles this season will be in comparison to before. It obliterates the group with ease, and the thought of XANA making more new monsters is not pleasant. Ulrich asking if XANA is still evolving proves to be dangerously prescient as this season's attacks all showcase him growing in power and intelligence.
• The debut of the Hermitage is just plain creepy. There's at first no reason to suspect anything will go wrong while the Lyoko Warriors are studying in the woods, but Aelita ends up being drawn to this strange, abandoned house and begins having all kinds of flashbacks there. Needless to say, it really helps set the disturbing and melancholic tone for the season's overarching plot.
• XANA's takeover of the Hermitage is also pretty bad, given that he ultimately manages to subject Ulrich and Yumi to a Sauna of Death and very nearly boils them alive.

• The introduction of Sector 5. It's completely unlike Lyoko's other sectors, being some kind of alien world full of moving walls and traps, completely unlike the more natural-looking Surface Sectors. Aelita is rightfully disturbed as she's suddenly taken there… and gets a front-hand view of the monsters native to it, first the Creepers… and then the Scyphozoa. Yup, this is when it debuted everyone, and it rightfully disgusts the Lyoko Warriors as they witness it draining Aelita's memories.

• The horrible revelation that the Return to the Past is making XANA stronger occurs in this episode. Ulrich says it best that the next battle is going to be tougher than ever, since they won't be able to rely on it so much to undo the damage, lest XANA get even more powerful. And if that happens, they're going to have to deal with it inevitably.
  • Said revelation? It comes with the fact that XANA has finally become powerful enough to possess people, and his first vessel is Sissi. What makes her particular possession stand out is how much of Sissi's personality seems to still be intact, but filtered through XANA's malevolence. Her lines really don't help, especially when Jeremie tries to get Sissi to resist.
    XANA-Sissi: I've never felt so good…
• A low-key one for the Scyphozoa, as it is confirmed to not be restricted to Sector 5. It can appear in any Sector, and does so in the Mountain Sector to attack poor Aelita once again.

• Overall, Aelita's flashbacks in this season are above and beyond some of the more intense and darker scenes in the show. Imagine that you've finally been brought into the real world… and then you have nightmares with strange people that you know nothing about, when you aren't dreaming of wolves hunting you through a forest while you're just a little elfin creature. And even after her memories return… the nightmares don't stop. Brr.
  • For this episode in particular, the nightmares appear as hallucinations, meaning that Aelita is tormented by them whether asleep or awake. You can just tell the effect it's all having on the poor girl.
• XANA attempts to possess Odd and Ulrich, and thankfully, it fails. That being said, resisting the process was definitely not fun for the two boys, as both are screaming in agony as their bodies resist the pixelization effect and force the Specter to retreat. They inform Jeremie, and at first, everything seems fine with it being the first time a XANA attack has failed… then Jeremie gets possessed instead.
• XANA-Jeremie ends up being a totally different beast from XANA-Sissi. As bad as Sissi was in the previous episode under XANA's control, she didn't display any real powers besides enhanced strength and fighting capability. But Jeremie? He's got that and is firing electricity from his hands in enormous quantities and displays the ability to jump incredible heights to boot. As he prepares to deliver the final blow to Odd, we can see the poor kid scared out of his wits as his possessed friend is about to heartlessly electrocute him to death.

• XANA-Aelita herself is pretty disturbing, and fun fact, this is her debut. XANA uses a Hypno Trinket to brainwash Aelita in the form of a necklace hiding a mind-control chip, which is rather alarming since it means that XANA has already figured out how to bypass the protection the scanners should give. She's basically electrocuted from the chip until XANA's symbol is in her pupils, and it's all downhill from there.
• Just how easily XANA-Aelita manipulates Jeremie, and then stares blankly at the audience during the trip to the factory, before using her powers to crush each of the Lyoko Warriors with ease.
  • The slow increase of XANA's visible influence on Aelita deserves mention as well. Not only does she look utterly creepy in the real world, but in Lyoko, her voice first becomes more high-pitched, akin to a witch, as she destroys the ground underneath Yumi's feet, before conjuring ice walls and fissures to restrain Odd and Ulrich… with the Eye of XANA now on her forehead as she does so. It's a subtle, disconcerting sight, but at the end, XANA ultimately has to relent in leaving Aelita alone as Odd is forced to fire at her in a last-ditch gambit to get XANA to back off. Hopefully this is just for one episode and won't ever happen again. Right?… Right?
    • Yeah, it happens again, and the concept expanded on to boot. It's already been revealed in XANA's section, so see the folders on Seasons 3 and 4 for how this concept continued on in specific episodes throughout the show.

• While the episode is mostly far from scary, XANA-Jim deserves an "honorable" mention. He pretty much mixes the evil personality thing that XANA-Sissi had with the powers XANA-Jeremie possessed. He can also clone himself. Odd and Ulrich end up having a pretty good idea of the fight they're going to have on their hands when they see that part.

• XANA's managed to manifest a large number of monsters before, but those were usually small-fry; Kankrelats, Bloks, Hornets… this episode proves that he's become strong enough to do that for the Krabs, and the Lyoko Warriors get face-to-face with around 20 to 30 of them.
  • To make things worse, for a good chunk of the episode, XANA uses a possessed Nicholas to remove the pain buffers on the Lyoko Warriors when they get hit, meaning any time they get shot, they'll feel it as if they were shot in the real world, and of course, if they lose all of their Life Points, they die.
• XANA-Nicholas is another example of a scary Xanafied individual. Throughout the entire episode, rather than moving like a human the way Sissi, Jeremie, and Jim did when they were possessed, XANA-Nicholas moves like a god-damn spider, cackles madly, and produces so much electricity it makes XANA-Jeremie's demonstrations look quaint.

• Jérémie really scores one with the titular Marabounta, which we really need to talk about in detail because it's one of the few times XANA isn't responsible for creeping us out.
  • To start, inspired by ant colonies, Jeremie creates a sort of purple goop that starts covering Lyoko, devouring every XANA monster in sight. Ostensibly, it's to make things easier for the Lyoko Warriors, but both Odd and Aelita are quite frankly disturbed by what they see as every monster XANA creates is destroyed by the Grey Goo. Aelita finds the carnage too horrible to keep watching, and Odd has his own choice words on the issue.
    Odd: I never thought I'd say this, but I feel really bad for XANA.
  • And then it goes after Aelita after it mistakes her for another XANA monster. Odd tries to chase it off by firing Laser Arrows at it, and that just triggers the thing to consider every living avatar and sentient program in Lyoko an enemy. Jeremie immediately tries to shut it down, but as it turns out, the Marabounta has become autonomous and can't be shut down. Oh, Crap! doesn't even begin to state the mess that Einstein's made today…
  • Just watch the scene where Yumi is Eaten Alive by the thing. Imagine how she must have felt. You have to wonder just why these kids even do this.
  • In the end, even XANA was shaken, as he drops any attempt of antagonism and pulls an Enemy Mine with the Lyoko Warriors to take the thing out, and when they succeed he pulls the only account of Villainous Valor he has in the entire series, and just lets the Warriors go. The fact that the Marabounta was so terrifying that XANA drops everything to help and then decides that the fighting is done for the day says it all.
    • And unfortunately for Jeremie, it's notably following this episode that XANA stops showing him any kind of mercy or chivalry. Instead of capturing him, XANA now just wants the kid dead, and given what Jeremie created, you almost understand why XANA is no longer pulling his punches in regards to the boy, as we'll see next episode.
  • In the end, the Marabounta was so disturbing it ended up becoming one of the few things that seems to have left actual trauma on the Lyoko Warriors, even among all of XANA's attacks before and after this episode. Odd and Aelita are understandably unnerved in Season 4 when Jeremie's plan to destroy XANA once and for all is basically a refinement of the basic function of the Marabounta via a true anti-XANA program, given the risks involved with combatting multi-agent systems.

• Also known as the time XANA took control of a dangerous criminal. It's particularly jarring as this is, in show canon at least, the only time the Lyoko Warriors have dealt with a human antagonist with a legitimate racket. Peter Duncan isn't some annoyance like Sissi or William, but a bona-fide criminal, wanted for numerous high-profile thefts. It's probably for the best that they didn't have to deal with him while not Xanafied.
• Just how casually Jeremie informs Ulrich (via cell phone) that after he replaces the Supercomputer's nuclear core, XANA-Duncan is going to kill him. No 12-year-old should be that calm in that situation.
• Let's not forget XANA's sadistic streak. When there isn't obvious pressure to keep him pragmatic he's been shown to take his sweet time killing, maiming, or destroying whatever he so chooses to. There is a very real chance that Jeremy wouldn't have ever been found or would have been found in several hundred pieces by the time XANA was done.
  • Given how this episode directly follows Marabounta, there's also probably a very good reason XANA's not interested in any Villainous Valor in regards to Jeremie…
• Slight but also very real, XANA forced Peter Duncan to steal a damn radioactive power source that doesn't seem to have any shielding. The whole factory, that career criminal, Jeremy after he got kidnapped, and the entire path that they took to get to the factory is probably contaminated now with at least some radiation.

• Jeremie attempting to increase his brainpower via a neuronal headset that could give him a boost the way XANA gets stronger from the Returns to the Past. He describes it as amazing with his increased capability, but also proceeds to become snappish and pushing the group away until he ultimately faints from the strain. The visuals while he's comatose, being stuck in a white hall as everything around him seems to turn black, do not do the scene any favors.
• It turns out that it was for nothing, all of the calculations Jeremie made under the influence were wrong. While it's at first suggested that it was a ploy by XANA, the real truth is that XANA already figured out that Jeremie was probably going to die from overusing the thing and was just launching attacks to get him there. The headset itself? It did come from Franz Hopper's notes, which makes Ulrich suggest that they might not have just one enemy, but two. Jeremie rebukes this, but this episode and "Marabounta" do not put Hopper in the best light, given just how dangerous his inventions and programs seem to be.

• XANA decides to give materializing his monsters another go. He sends out the Krabs, and they prove far more lethal and strategic than the Kankrelats did. They deliberately smash the scanners so Aelita will be isolated on Lyoko, and then specifically hunt down the Lyoko Warriors at Kadic and the suburbs. Their stronger laser power likewise goes without question, and once again we see what happens when XANA's monsters attack in the real world. Suffice to say, it isn't pretty.

• The title says it all: XANA possesses Kiwi, Odd's pet dog, and uses him to spread a zombifying virus through the school. Most of the group is trapped in the cafeteria, and William is trying to keep them there (in fairness he doesn't know about Lyoko yet, and in a Deleted Scene, he even violently punches Jérémie in the gut, saying he's the one in charge). Odd is bitten and Ulrich and William have to restrain him. Imagine seeing your best friend gagged and tied up and trying to bite you while moaning in the Voice of the Legion.
  • The worst part? Thanks to Loophole Abuse, this doesn't counts as XANAfying, meaning that the Lyoko Warriors are not immune to this one.
  • Jeremie gets bitten before Aelita deactivates the tower and has a horrifying transformation. He can barely gasp out 'Return to the Past now!' and his voice is already changing… if Aelita had been seconds late…

• Just how quickly Odd and Yumi deteriorate in this episode due to being Locked in a Freezer. Yumi starts shivering first and by the time XANA has gotten tired of waiting for Aelita to give herself up, is reduced to being barely able to stand and weakly crying Odd's name as XANA prepares to kill him.
  • And then there's the added idea that Odd might have accidentally caused XANA's later attack of creating an obscenely cold blizzard four episodes from now by telling XANA that cold is lethal to humans.
  • Fun fact, this is the second time XANA ever unambiguously communicates with the heroes. He sends them a text message, simply saying to deliver Aelita to the Scyphozoa within a certain time, else, he'll kill Odd and Yumi. No theatrics like other cartoon villains. Here's the message: cold, simple, and to the point:
  XANA: Aelita at two o'clock to give herself up to the Scyphozoa. If not, Odd and Yumi will be liquidated.
• Xanafied Delmas is likewise rather intimidating because of his actions. First is his immediate kidnapping of Odd and Yumi, beating up William in the process as he just flat-out grabs them from the school. As a reminder, the world of Code Lyoko may not 100% match reality… but it's certainly a lot more grounded than other cartoons, and so Delmas committing such a blatant crime gets the cops involved, increasing the sense of dread.
  • Sissi's fear for her father's life after Ulrich uses Jérémie's EMP bomb on him deserves a mention, if not the entire situation from her perspective, as she's utterly worried about him dying. Thankfully, she doesn't have to worry about that. Instead, she gets to helplessly beg her father, under the control of a murderous A.I. who possessed her a while go, to not kill Ulrich, which only puts her in danger as XANA-Delmas blasts her away.
  • Continuing with XANA-Delmas, besides locking Odd and Yumi in a freezer after kidnapping them, he continues to be an Implacable Man as it turns out the EMP only knocked him out temporarily. He turns out to have Super-Speed as he catches up with the group and attacks them on the Factory bridge, and as the cherry on top, laughs as he electrocutes Sissi, showing once and for all that the second you get into XANA's crosshairs, he will hurt and/or kill you for helping the Lyoko Warriors… and that's assuming that you weren't an indirect target to begin with.

• Jeremie learns the hard way that Evil Is Not a Toy. Once XANA figures out that Jeremie is using the polymorphic specter against him to fight XANA-Yolanda, he overtakes the tower and attempts to kill Odd either by overloading him with energy and destroying him from the inside out, or draining his life force like a vampire. It's no wonder Jeremie never attempts to use an activated tower again until season 4.

• XANA takes control of a pack of wolves. At first, it seems that he's only generated images, but it turns out out he's legitimately possessed three wolves and they quickly start trying to maul the group to death. Ulrich tries to hold them off, and while he succeeds in letting Odd and Yumi get to Lyoko, he's not able to beat them, and is just flatout nearly mauled to death by them near the end.
  • The episode really hammers in, somehow, the amount of times Ulrich has nearly died in general. No child would be perfectly fine with that, not even mentioning how many of them were different e.g. burned alive/dehydrated to a dangerous degree, crushed, frozen, mauled to death, etc. Is it because of it focusing on his fears or just how visceral this particular method was?

• XANA's increasing power and intelligence looms its ugly head once again. Now XANA has learned to activate and deactivate Towers in succession, essentially learning how to time his attacks. His attack here is an inhumanly cold blizzard that gets to at least forty degrees below, and could easily get even colder. Oh, and as another demonstration of his powers? Monsters previously exclusive to Sector 5, i.e. the Mantas, are now on the surface sectors, and they're quick to use their mine-laying abilities to make hazards that even the Hornets couldn't manage.
• Yumi nearly dies from the cold because she was also trapped under a heavy tree. It's all Ulrich can do to comfort her as both he, her, and everyone in the city slowly freezes to death. But when the attack ends and things warm up, Yumi isn't moving, to Ulrich's alarm and horror. A quick Return to the Past saves her just in time, but it really keeps hammering in how horrible the situation the Lyoko Warriors is that they're facing an enemy who has been trying to kill them with practically everything he can think of.
• As the blizzard worsens, Jim takes all the students to the boiler room and tries to keep their morale up by telling stories of his past. He gradually succumbs to the cold, and ultimately drops to the floor with his eyes wide open and ice covering most of his face, implying that he's gone into shock. It's one of the most horrifying scenes in the show, as it explicitly displays a human being's torturous decay until he is on the brink of death.

• Aelita gets hit with visions and hallucinations again, which continue to put Franz Hopper in a more and more ominous light as Aelita keeps seeing him, not knowing what the hell is going on.
• The confirmation that XANA was behind increasing the visions is hardly anything pleasant either; he used their connection to drive her to such desperation that she would basically go to Sector Five unguarded and run right into the Scyphozoa.
  • It gets worse when you learn that these weren't random, but Aelita's actual memories that XANA was transmitting. The poor girl was being driven to near madness by her own traumas that she had no context for.

• The episode already starts off with a lovely concept. Five Towers activated at once. The idea that XANA's become that powerful should be sending bowel movements to everyone watching. Thankfully that wasn't true in the end.
• Franz Hopper debuts… and with a horrifying revelation. The Scanners were not yet properly tested for human use, and thus there is a risk of cellular degeneration. All of a sudden, the entire premise of the series collapses, and not in the way horrible revelations like the Evas being cyborgs or Magical Girls being destined to become Witches go down. Nope, the scanners can potentially kill you, and what do you know, while Odd and Ulrich seem to be fine, Yumi is not. The group basically shatters at this, and the three main Lyoko Warriors (Aelita of course, being the exception) want nothing to do with Jeremie for basically leading them to what seems like inevitable death.
  • While this part is thankfully revealed to be false, even Jeremie had to admit that the risk was bad enough to do a complete recheck of the system. He was able to determine that yes, the scanners were thoroughly tested by Franz, and thus there is no risk of cellular degeneration. No matter what you think of how the group reacted, the sheer idea that their adventures could do that to them is a revelation that well and truly nearly broke them, it was THAT bad.
• The polymorphic specter's reveal as Franz Hopper is already bad enough, hearing Franz's voice speak in such a malevolent and scheming way. Given the way he acted as far above most Polymorphic Specters or possessed humans in intelligence and language, it's not hard to imagine that this specter could very well have been another incarnation of XANA ala Ghost Channel, being yet another indication of XANA's horrific malignant nature.
  • Also, after Jeremie discovers that this Franz Hopper is actually a polymorphic specter in disguise, it gets pissed at him, and eventually turns into smoke to invade his airways, and proceeds to suffocate him while Ulrich can do nothing but watch.

• The virtualized polymorphic specter in this episode. It's incredibly creepy to look at, specifically using the art-style from Season 1 as a hint to viewers that "Odd" isn't who he seems. And just as creepy when it silently shoots at Ulrich and Yumi, with none of the wit and banter we'd expect to hear from Odd.
  • Then it gets worse, as it turns out that when virtualized, polymorphic specters can take on the form of other virtualized Lyoko Warriors, gaining a complete copy of their powers. Ulrich's reaction to it taking on a demonic reflection of himself says it all.
• Odd's drowning in this episode is particularly disturbing since it involved him taking the bait when XANA pretended to be a girl asking him to meet in the woods. It would appear that Odd's parents' hands-off raising method severely hampered his ability to remember 'stranger danger'.

• Waldo Schaeffer/Franz Hopper finally and truly debuts as Jeremie looks at the recordings of his diary back when he was creating Lyoko. We learn that Franz was forced to use the Return to the Past 2546 times, living the same day over and over again. To be blunt, the process drove him insane. He's quite clearly paranoid and unstable as his diary demonstrates, though thankfully, he seems to have pulled himself together in the present-day of the series.
• The reason for XANA and Lyoko's creation was to destroy something called "Project Carthage". To this day, fans have speculated what it is; based on the novels (which have their own folder) and Evolution, it was a project designed to effectively take over the entire worldwide network and put all of the power seen in Lyoko and other virtual worlds in the hands of a singular individual. Whether XANA succeeded in destroying Carthage in the original canon proper or not is still unknown, but however it went down, it attracted enemies for Hopper, and he was clearly at his wits end, desperate, thus forcing the above scenario.
• We also learn why XANA's been sending the Scyphozoa after Aelita. It's to get his hands on the Keys to Lyoko, which as we learn in Season 4 basically gives him the freedom to copy himself onto other supercomputers in the network by infecting them with Replikas of Lyoko. Obviously this concept wasn't fully finalized in Season 2, but the dread of what XANA would do with the Keys is very apparent. Let this exchange spell it out.
  Jeremie: The Keys to Lyoko...that's what XANA's been trying to steal from Aelita's memory!
  Ulrich: But what could XANA do with them?
  Aelita: ...Escape from the supercomputer...and Take Over the World...
• Aelita reaches the orb that seems to hold the fragment of her human self. Except it was a trap. XANA destroys the entire room, devirtualizing Ulrich and leaving Aelita completely alone. Alone with the Scyphozoa, which finally succeeds in draining the Keys to Lyoko from her memory. Aelita is effectively braindead, and Sector 5 completely darkens as every Tower on Lyoko activates at once. It soon becomes clear what this means as XANA's essence emerges from the factory as a massive black storm, lightning crackling as he is freed from the confines of Lyoko.
  • In other words...XANA is free, repeat, XANA is free, and there's not going to be any easy way to defeat him from this point onwards.
• Aelita's flashback of first being virtualized. While heartwarming to see her with her parents, things quickly take a dark turn as Anthea's image vanishes, and then desperate as the painting-like images fade away to the regular art-style, with The Men in Black, all but certain to be with whatever organization was associated with Project: Carthage, outside her window. The nightmarish music in the background certainly sells the sheer desperation in Aelita's situation as Hopper takes her to the Factory, sending them both to Lyoko.

• Here's our first glimpse of how much stronger XANA has become following his liberation from Lyoko. Originally, to possess multiple people, he needed to first create an infection vector of some kind, as seen when he took over Kiwi. This is no longer the case. XANA is now free to possess multiple individuals, and he starts off by possessing Yumi's entire class. She's suitably horrified, as are the rest of us.
  • As a quick-note, while her fellow classmates seem to be a bit weaker than the usual, since William is able to knock them out, the same can't be said of Jim and Miss Hertz, who still have all of the power you'd expect from a Xanafied individual from the last season. They take out William, Yumi, and Ulrich in short order and are close to flat-out killing the latter two.
• XANA-Aelita returns, and her appearances here and in the rest of Season 3 are hardly any better than he debut, where she proves to be a scary No-Nonsense Nemesis as XANA's monsters shift gears from firing at her to becoming her bodyguards.
  • For this episode in particular, just how unsettling it is to see the Scyphozoa return, entangle Aelita again, and seemingly drain her once more. But as Jeremie notes, it's instead implanted something into her memory, and what that implant is becomes scarily obvious as her eyes open and she flings Odd away with one hit. The Eye of XANA is present on her once again, and we soon realize that Aelita is now XANA's envoy...and will be for the rest of the season each time the Scyphozoa gets to her.

Aelita

• We learn what happened when Aelita was virtualized on Lyoko for the first time. Hopper wasn't able to create a proper avatar for himself, only appearing as several small white spheres, and as soon as they landed, XANA attacked them. Hopper tried to communicate with his creation, but whatever happened didn't turn out well; XANA was now autonomous, and Hopper had no choice but to shut down the supercomputer.

The Pretender

• XANA continues his animal possession terrors by taking over a murder of crows, and much like in the infamous 1963 horror classic film The Birds they almost shred poor Yumi into pieces. Literally she was screaming while they were pecking her into a coma (in a not too similar scenario to the iconic phone booth scene with Melanie) while she was hiding out in the garden shed. If it hadn't been for Jim and Principal Delmas arriving at the right moment, Yumi would have been found dead in a horrible mash, and she was still barely alive on the way to the hospital, luckily she was saved with a Return to the Past.
  • They also manage to get to Jeremie, and use the remaining time in the attack to peck him to unconsciousness. About the only thing that spared him from the same beating that Yumi took was the fact that Aelita had just gotten into the Tower. Otherwise, they might have done far worse to him...
• XANA-Aelita once again appears, this time getting in a more protracted fight against Ulrich, while his katana has been destroyed. Ulrich tries to tell Odd to try to launch a Return to the Past, as the Tower was deactivated earlier. But there's one issue: XANA-Aelita becoming permanent if an RTTP is launched while she is under XANA's control. As such, Jeremie refuses to use the Return to the Past function should she pop up, and Odd, who usually tends to joke about the Supercomputer programs is in full-blown agreement with the idea. All Ulrich can do is try to fight her with his bare hands...and he ultimately doesn't succeed, XANA-Aelita reaches the Way Tower and enters Code:XANA. The Desert Sector is destroyed not too long after.

Double Trouble

• The specter in this episode is one of the most unnerving villains in the show. It gets this close to murdering Jeremie, and is so good at impersonating him it successfully fools everyone it interacts with. It's also much more talkative, and manages to show how deranged and cruel XANA is in spite of being a soulless computer virus.
  • There is also the way it's defeated. After Aelita destroys the last sector on Lyoko, it uses its last moments to electrocute Ulrich to near death, all the while grinning creepily at the camera, before fading away.
  • Jeremie calls Odd in the middle of the episode to warn him of the imposter… only Odd is in the presence of the spectre at that exact moment. In the French version, as the spectre approaches him, you can hear it growling at Odd like an animal. What the hell was wrong with that clone?

Final Round

• The debut of XANA-William. He quickly proves to be different from XANA-Aelita, and not in a good way. Instead of being a cold, No-Nonsense Nemesis, William under XANA's control seems almost bestial and demonic, growling at Aelita as he brandishes his sword at her, before devirtualizing her in one hit. His next scene is one of absolute terror as he is commanding an army of at least fifteen Creepers, all of them (as well as him) aimed at the Core of Lyoko. We also see him struggling shortly after giving the order to prepare to fire, indicating that William is fully well-aware that he's under XANA's control...and ultimately helpless to stop himself.
  • His power level cannot be understated. XANA-Aelita tended to keep away from the Lyoko Warriors, but XANA-William is a full-blown juggernaut able to drop from a great height and leave a crater in his wake. He soon proceeds to defeat Ulrich, Odd, and Yumi in quick order, with Ulrich and Yumi both getting impaled by his sword.
• The destruction of Lyoko might bear mention. The chaotic destruction here is not like how it was in "The Key". XANA-William is surrounded by devastating orange energy as Lyoko collapses in on itself with the Core now destroyed...and when it's assumed that William has been deleted, in truth, XANA has salvaged his code, and completely remade William into his personal envoy. The reborn XANA-William opens his eyes, a mechanical hissing in the background, before roaring, fully in his new master's thrall.

William Returns

• We've talked a bit about XANA-William in general, but this is the episode where he returns, and right from the get-go we know that bad things are going to happen when he's virtualized and his theme tune starts up, with haunting, wailing variants that we don't get for the remainder of the Season. He debuts his Super Smoke ability, and we see just what kind of dark being XANA has fully twisted William into as he continues to manhandle the Lyoko Warriors, with the intention of throwing Aelita into the Digital Sea in the process. Jeremie puts it best near the end when William retreats into the Digital Sea.
  Ulrich: "You think William's gone for good?"
  Jeremie: "...No. I think he just went back to his new master...XANA."

Crash Course

• XANA's polymorphic specter this episode, rather than electrocuting Jeremie itself, decides to shock him with one of the power cables for the supercomputer itself. It damn-well nearly kills the kid, and the relief in Yumi's voice that Jeremie is still alive shows just how close Jeremie came to meeting his maker.
• In a Deleted Scene (script-only), Aelita has a flashback to her past when seeing the specter in this episode, which took on the form of a MIB agent. The question thus arises: why did XANA choose that form to begin with?

Hot Shower

• The sheer apocalyptic despair as XANA takes control of the Kill Sat from "Satellite" again, this time to strike at a large comet and have the fragments rain down on Kadic and the factory. After his previous attacks in the season so far were just countering the Lyoko Warriors' investigations on the network/dealing with William's absence, XANA returns to his mass-destructive roots as meteorites begin raining down on the town.
  • One small note: If you wanted a reminder that the XANA of Season 4 is a very different beast from Season 1, at least in Season 1 he needed time to take over the satellite. Now? He's powerful enough to just do it instantaneously, with no delay whatsoever.
• The fact that XANA's plan was pretty much airtight; delay the Lyoko Warriors as much as possible and render hacking into the satellite impossible. Jeremie and Ulrich realize that there's no way that they can win, until Aelita has Odd devirtualize her to force XANA to cancel the attack altogether, given that he needs her alive. It's a reminder that no matter how often XANA's attacks seem to fail, he is not a laughing matter.

The Lake

• The lake-sludge monster in this episode deserves mention as XANA attacks the Lyoko Warriors directly at class when they're supposed to be on a field trip. Or rather, the reactions of their classmates. There's not much comedy to be had as XANA begins electrocuting everyone on the island, with students flatout crying in terror. It's another reminder of how godforsakenly murderous XANA is, and how he will not spare anyone who gets in his way.
• Even at the episode's end, Jeremie admits that yes, no matter how the Lyoko Warriors might snark at them, XANA attacks are scary, and each one still frightens him. Given how violent this one was, you really can't blame him, and then just look at how these kids have just kept on doing this for so long...

Lab Rat

• We finally start seeing the source of XANA's Replikas, beginning with a research facility located in the Amazon Jungle. What's he making there? Oh nothing, just a bunch of cybernetic spiders◊ after possessing the scientists working there.

Bragging Rights

• Following right after the previous episode... the spiders are out. Repeat, the cyborg spiders are now loose. Yumi is suitably disgusted by them and runs off, but it really doesn't help her or Ulrich as the spiders manage to overwhelm them and send them back to the Skid. Thank god Odd was able to destroy the supercomputer's backup generator and kill them all.
  • One quick note: The scientists who were possessed by XANA are not in this episode. The show itself never tells us what happened to them, but Sophie Decroisette ultimately confirmed that yes, XANA killed anyone who was deemed an impediment to his plans off-screen. Which means he has an official body count now. A number of which we don't know. That maybe no-one in the world will know, in-universe or out. Joy to the world...

A Lack of Goodwill

• At first, this seems like a rather standard episode... and then William comes back to Earth, still under XANA's control, and accomplishes an impressive amount of damage: he busts Jeremie's ankle, deletes the 'good' clone Jeremie made of him, almost critically overheats the supercomputer, and stomps at a harmless little girl (i.e. Milly) to scare her. The entire time, he's either smirking or scowling - and he's quite chatty the entire time, too. Since XANA is not directly possessing him, either this means that whatever is possessing him has picked up on human cruelty, or William himself has been altered…

Distant Memory

• We open up with a new nightmare sequence from Aelita, this time showing her POV as her mother was kidnapped. As it turns out, she saw the whole thing play out, but was too young to truly understand the full details. The imagery of Anthea being taken by the Men in Black, all while a wolf is watching Aelita, is hardly anything pleasant to look at.
  • Hell, the idea that the MIB are still a thing is a disturbing thought in of itself. Again, the show never really confirms if XANA took them out during the days of Project: Carthage, and if he didn't, if they're still out there...
• The Simulation Bubble from "Ghost Channel" returns, and while it isn't as big as it was before, and XANA thankfully isn't directly appearing as some horrible monster...XANA-William showing up, as talkative and malignant as he was in the previous episode, is hardly any better. Aelita having to run from a clone of her father turning into a wolf is likewise fairly ominous and a real dick move from XANA given that he likely knows most of Aelita's trauma regarding wolves.

Wrong Exposure

• XANA-Aelita's back. And she's now as bloodthirsty as XANA-William if not moreso, robbing Ulrich of one of his swords and proceeding to damn near beat him into submission. Ulrich is only saved thanks to Jeremie's new reset program shocking Aelita back to normal. Let's be glad that this was her only appearance this Season and that XANA-William didn't show up to give backup...
  • But of course, to add a bit more horror to this, throughout this season, it is implied several times that XANA does know of what he could accomplish if he had Aelita with him permanently, but intends to kill Hopper first before he makes Aelita his. XANA powered up William to an insane degree, turning an above-average Lyoko Warrior into a near-broken force of destruction. This episode showcases that everything that's been done to improve on William's combat capability can easily be transferred to Aelita, and she was already hard to deal with in previous seasons when under XANA's control. Overall, this episode gives a very good indication of what horrible monster XANA would have made Aelita into if he managed to get his hands on her permanently.
  • Want to make this concept even scarier as a final top-off? Rewatch "Ghost Channel" (where Aelita proves she's able to essentially do the same things XANA could do in the first season, and without needing the towers, could do so unopposed if she wanted to) and then imagine what she and XANA could accomplish if he was able to control her more often. Actually, let's stop imagining it, because if Aelita was in XANA's clutches permanently, that's game over, since there would be no way to deactivate Towers ever again.

Cold Sweat

• XANA-William has been teleported. Repeat, XANA has managed to teleport William. His appearance via dark green lightning is a major indicator that things are not going to be easy for the Lyoko Warriors at the Ice Replika. Yumi and Odd manage to fight him off a bit at first, but ultimately none of their attacks seem to actually hurt him. He just keeps on going and was damn-near close to finishing them off before Aelita deactivated the Tower maintaining his teleportation.
• The experiments XANA is up to at this particular base. He seems to be growing brains. Odd is suitably disgusted. The question remains...where did they come from? The scientists at the facilities he's already taken over? Or are they legitimate artificial brains? Best not to get the answer to that...
• We talked briefly in XANA's folder about the Kolossus. This is the episode where it debuts, crushing Aelita and Ulrich with ease, prompting Jeremie to get Odd and Yumi evacuated from the Ice Replika ASAP. Both Odd and Yumi are horrified when they see the thing, with Odd being horrified by its appearance.
  Odd: He's probably as mean as he is ugly!
  • The appearance of the Kolossus also bears mentioning, since it reveals something very unsettling. XANA's Replikas aren't limited to just five or so copying Lyoko's sectors...he has hundreds of them across the entire globe. There's absolutely no-way that the Lyoko Warriors can destroy them manually, putting them right back at square one. The only thing keeping this from being a crushing moment is Jeremie thankfully brainstorming an alternative, giving some hope that XANA can be stopped.

Down to Earth

• Code Red is in place for this episode with the revelation of XANA's masterstroke; a nearly completed robot army. Not just some small guerilla forces like at the Jungle Lab or Space Station, a full-blown army of robots with beetle-like heads and eyes. And as Aelita and Odd discover...they're operational, and don't seem to need Towers to move. The two are soon on the retreat as the robots fire and chase them down, and Aelita sums it up perfectly.
  Aelita: Jeremie, it's a nightmare!
• The ending of the episode is somewhat uplifting, as William is free, but the Skid has been destroyed, leaving the Lyoko Warriors helpless in traveling the network. And the robots in Siberia are still operational, with the very real possibility of there being more out there, given how many Replikas XANA has. The clock is ticking, if Jeremie doesn't finish his anti-XANA program soon, XANA may be ready to really and truly take over the world.

Fight to the Finish

• The group decides not to send William to Lyoko since he just got freed from XANA's influence. XANA decides to make them regret that decision, and immediately possesses William's body again, prompting Yumi to devirtualize herself and fend him off to protect Jeremie. What follows is the most brutal beatdown ever seen in the real world. She gets launched, stalked, and toyed with for several minutes. It's hard to watch, and it isn't treated lightly at all.
  • Ulrich gets in on it after his devirtualization and though he gets some progress against William, he's kicked so hard against the wall that he's rendered completely unable to defend himself.
  • XANA's death (Or not, if Evolution or the novels are of any indication). As the multi-agent system meant to destroy him surges through the network, XANA is slowly expelled from William's body, emerging as a giant made of black smoke, clutching his head in pain, moaning and screaming all the while. Finally, as the last Replika is destroyed, XANA morphs into a massive black mass screaming in agony as he's deleted once and for all. Even Ulrich and Yumi were horrified.
  Ulrich: What's going on? (referring to the giant, agonized specter)
  Yumi: …I don't know.
  Jérémie: XANA is dying…

• XANA as Eva has determined the fastest way to get a necessary item is to maim whoever has it. When a passerby woman with her dog sees a girl in a hospital gown, obviously weak and confused, she stops to check if she's alright. XANA realizes it's because duh, humans wear clothes and what he has is considered too little. The next thing we see? XANA-Eva calmly walking away in oversized clothes, while the lady's dog barks desperately.
• Hannibal Mago makes much more of an impact than Tyron. He's abused Anthea and erased her memories, is a ruthless criminal who Would Hurt a Child, and starts to go insane as he realizes just what capabilities Lyoko has to offer him.
• Whether or not it is canon to the actual series, we learn that the scanners can only properly virtualize children, due to forming an avatar based on their subconscious. Children do not have much to worry about, enabling the scanners to form a cohesive avatar for them. Adults, due to having faced the stresses of real life, are too unstable for the scanners to process, and end up as incoherent Eldritch Abominations, with only Hopper managing to keep his sanity intact. Again, we don't know if this is fully canon… but still, rather unsettling all things considered.
• The flashback of Aelita being shot in the head while she and her father try to run from The Men in Black, followed by Franz's terror for his daughter. Worse, there's no indication the man who shot her was punished for it.
• You remember how terrifying XANA was in the original show? Well, the novel reveals he became that way when he got infected by a virus. Specifically, a virus from the castle hosting Project Carthage. That suggests Project Carthage was so malevolent that even without being sentient, just being nearby was enough to turn a once-friendly AI into a monster. No wonder Hopper wanted it destroyed.
  • Speaking of, Hopper also reveals that he couldn't destroy Carthage no matter how hard he tried, which is why he locked it up and had XANA guard it in the first place. Reminds one of the Marabounta, doesn't it?