History Characters / UndertaleYellow

* BrilliantButLazy: While she is quite skilled with building traps and puzzles as a Royal Guard, [[spoiler:a flashback of a talk between her and Chujin in the Genocide Route reveals not only she's been freeloading most of her life, but also that she joined the Royal Guard because she figured that aside from the trap and puzzle building, they only sit around all day, which made her think the job was perfect for her, while also innocently assuming she's good enough with people that she can handle a human showing up]]. It's to the point that [[https://twitter.com/undertaleyellow/status/1093928039782801408?s=46 a comic]] by the game's artists show her showing up at work and immediately falling asleep at her post. All of this leaves Martlet horribly underprepared for when she actually has to do stuff beyond that, especially when an actual human, Clover, shows up.

* MyGodWhatHaveIDone: His reaction when he discovers that his creation Axis murdered a human child, when all he wanted was for them to be apprehended.

* PresentAbsence: His death is what set Kanako and Ceroba's tragedy into motion. After learning that boss monsters are immortal until they have children, Kanako blames herself for his death, and she resolves to help contribute to his legacy by having Ceroba inject the human SOUL serum into her. Despite Chujin's explicit warning to Ceroba to not use Kanako in the experiment, Ceroba relents and injects her because of how badly Kanako wants to help his plan succeed.
* ProfessorGuineaPig: He died because he tested his experimental serums on himself, deteriorating his soul until it was impossible for him to remain alive.

* ScientistVideoJournal: He kept a tape journal where he detailed his experiments on the [=SOULs,=] now hidden in his secret lab.

* WalkingSpoiler: Chujin's experiments, failures, and prejudices have major and long-lasting impacts on both the Pacifist and No Mercy routes, but the player doesn't learn about them until the very end of either route.

* {{Irony}}: Chujin was a gifted carpenter who chose a career laboring in the sciences instead, and spent the last few years of his life covering up the truth about his work to everyone around him -- in other words, he was a liar who tried to be something that he wasn't. He ultimately dies because his SOUL rejects his attempts to infuse it with the blue human one, which represents Integrity. Additionally, his {{Leitmotif}} is called "Nothing But The Truth".

* {{Irony}}: Chujin was a gifted carpenter who chose a career laboring in the sciences instead, and spent the last few years of his life covering up the truth about his work to everyone around him -- in other words, he was a liar who tried to be something that he wasn't. He ultimately dies because his SOUL rejects his attempts to infuse it with the blue human one, which represents Integrity.
* {{Leitmotif}}: "Nothing but the Truth", an incredibly ominous tune that plays while his tapes are being played.
* MadScientist: Chujin's experiments, especially towards the end of his life, were unethical, poorly-tested, and based in evidence that was flimsy at best. Notably, he had the ambition and flexible morals of the classic MadScientist but not the talent, so most of the harm from his research came down on himself and his family.

* ScientistVideoJournal: He kept a tape journal where he detailed his experiments on the SOULs, now hidden in his secret lab.

* UnusualPetsForUnusualPeople: She has not one but ''three'' pet snakes wrapped around her neck.

*** [[spoiler:Double points for irony is that Martlet dies believing that Clover would go on to slaughter countless more monsters mindlessly. The only monsters they kill afterwards is Flowey, [[KickTheSonOfABitch who absolutely deserved it]], and Asgore because they needed his SOUL to pass the barrier, and once they obtained said SOUL, they left the Underground immediately, as they now had completed their mission and no longer had any reason to stay there.]]

* FateWorseThanDeath: [[spoiler:She was sent to Alphys' lab along with many other fallen down monsters, meaning she has unfortunately become an Amalgamate, with it being heavily implied that she's the Amalgamate that tucks Frisk into bed in the TrueLab.]]

* FateWorseThanDeath: [[spoiler:She was sent to Alphys' lab along with many other fallen down monsters, meaning she has unfortunately become an Amalgamate.]]

* AdaptationalVillainy: In ''Undertale,'' the only description for the Old Tutu and Ballet Shoes in Waterfall was that the former is covered in dust and the latter made Frisk feel "incredibly dangerous" when putting them on, [[AmbiguouslyEvil leaving it ambiguous whether Integrity killed monsters maliciously or out of self-preservation]]. Outside of that, they help Frisk out during the Neutral and Pacifist routes like the other souls. In ''Undertale Yellow,'' however [[spoiler: they come across as distinctively more morally dubious.]] [[spoiler:They almost killed Kanako and Dalv in retaliation for being attacked by the latter, [[WouldHurtAChild the former being a young child]], is overall described as violent by the other characters and sources, had killed several monsters during their attack in Snowdin, and is ultimately killed by Axis in Waterfall when they attempted to flee from the monsters (albeit unintentionally).]] [[spoiler Their SOUL would continue to cause problems even after their death, getting Chujin killed when it kept refusing to allow themselves to be absorbed so he could fuse their [=SOUL=] together with his slowly deteriorating his SOUL as a result, and being indirectly responsible for Kanako's becoming Fallen Down.]]

*** Both are [[FantasticRacism human-hating]] denizens of the Underground who made plans in secrecy to help monsterkind, with said plans involving the use of a human SOUL mixed with a monster. Both plans ended up in failure, with the two of them dead by the end and leaving their families fractured. Both are [[PosthumousCharacter long-dead]] overarching characters in the story, wear green, have parts of their story shown through tapes hidden in a lab, are known to start conversations with "greetings", and both have names starting with "Ch".

* AdaptationalVillainy: In ''Undertale,'' the only description for the Old Tutu and Ballet Shoes in Waterfall was that the former is covered in dust and the latter made Frisk feel "incredibly dangerous" when putting them on, [[AmbiguouslyEvil leaving it ambiguous whether Integrity killed monsters maliciously or out of self-preservation]]. Outside of that, they help Frisk out during the Neutral and Pacifist routes like the other souls. In ''Undertale Yellow,'' however [[spoiler: they come across as distinctively more morally dubious.]] [[spoiler:They almost killed Kanako and Dalv in retaliation for being attacked by the latter, [[WouldHurtAChild the former being a young child]], is overall described as violent by the other characters and sources, had killed several monsters during their attack in Snowdin, and is ultimately killed by Axis in Waterfall when they attempted to flee from the monsters (albeit unintentionally).]]

* {{Foil}}: To Alphys:
** Both are scientists who ultimately want to use their smarts for the benefit of monsterkind, both have created sentient robots, and both have incredibly dark secrets.
** He had more confidence in himself, in comparison to Alphys who was a nervous wreck.
** Their creations are viewed completely opposite to one another. Whereas Axis is seen as a lost cause, and looked at unfavourably, Mettaton is seen as a global sensation. However, despite this, Axis is a fully sentient robot capable of feeling anger, remorse, fear and love, while Mettaton was just a ghost that possessed and merged with a robotic body.
** In regards to their determination/human soul experimentation, Alphys' involved fallen down monsters, whereas Chujin experimented on himself. Both ended poorly, [[{{Understatement}} to say the least]].

* AdaptationalVillainy: In ''Undertale,'' it's [[AmbiguouslyEvil ambiguous as to whether Integrity killed monsters maliciously or out of self-preservation.]] Outside of that, they help Frisk out during the Neutral and Pacifist routes like the other souls. In this game, [[spoiler:they're firmly in the malicious category. They almost killed Kanako and Dalv, [[WouldHurtAChild the former being a young child]], and is overall described as violent by the other characters, ultimately being killed by Axis in Waterfall (albeit unintentionally). Their soul continued to cause problems even after their death, getting Chujin killed when it kept refusing to fuse their [=SOUL=] together with his, and being indirectly responsible for Kanako's possible fate as an Amalgamate.]]

* TranquilFury: [[spoiler: Chujin's secret tapes reveal that he had tried to fuse his SOUL with Integrity's several times to further his plans to aid Monsterkind, but each attempt was met with rejection from them, resulting in him having to experiment with their SOUL further to find a different way to get what he wanted, which eventually lead to the Serum that caused Kanako's condition. It would be pretty safe to assume Integrity was not happy about being killed, and even more pissed that the monster responsible for their death, was trying to permanently fuse their SOUL with his.]]

* OccidentalOtaku: His love of anime could give Alphys a run for her money.

* TranquilFury: [[spoiler: Chujin's secret tapes reveal that he had tried to fuse his SOUL with Integrity's several times to further his plans to aid Monsterkind, but each attempt was met with rejection from them, resulting in him having to experiment with their SOUL further to find a different way to get what he wanted, which eventually lead to the Serum that caused Kanoko's condition. It would be pretty safe to assume Integrity was not happy about being killed, and even more pissed that the monster responsible for their death, was trying to permanently fuse their SOUL with his.]]

* OneWingedAngel: [[spoiler:Before Clover battles her atop the rooftop in the Genocide Route, she injects herself with Determination, and transforms herself into the Zenith of Monsterkind.]]

* OccidentalOtaku: Gives Alphys a run for her money in this regard.

* TheEeyore: He's in the throes of a mid-life crisis, so he's a bit on the morose side.

%%[[caption-width-right:92:''"Yellow is the new black."'']]

* WingedHumanoid: His body shape.

* ArtAttacker: Her attacks involve drawing lines on the board.

* SdrawkcabName: It's a living mirror whose name is "mirror" backwards.

* BlatantLies: Unless coaxed out of its shell with a dance, it will always insist that it's just an igloo. Its dialogue for being hit is, "Ow! I mean... igloo noises"

* TheReasonYouSuckSpeech: [[spoiler:Gives one of these to Clover as she dies on a Genocide run.]]

-->'''Axis:''' [[spoiler:[="BRuTE FoRCE_WON'T S0LVE ANyTHING. TRY ALL yOU LIKE BUT tHE STEAMWORKS...ALL oF US. WE ARe SURVIV0RS."=]]]

* IDidntMeanToKillHim: What he tells [[spoiler:Clover at the end of his Genocide battle, referring to his murder of the Blue SOUL/Integrity. Clover cuts him off before he can elaborate more]].

%%[[caption-width-right:92:''"You can do this!"'']]