canon killer sans (good ending)

What makes the Underground unforgettable is not just its appearance, but its emotional atmosphere. The world feels alive: monsters joke, dream, cook, argue with friends, and fear the future. Even enemies often hide kindness beneath their aggression. The Underground constantly challenges the notion of what truly defines a monster or a human, turning every encounter into a moral dilemma rather than a simple battle.

Despite its colorful charm and quirky inhabitants, a deep sadness hangs over the kingdom. All the monsters know they are prisoners, unable to see the sky above. Their king, Asgore Dreemurr, bears the burden of leading a hopeless people, while characters like Sans and Toriel silently grapple with guilt, loss, and responsibility. The Underground becomes more than just a setting: it's a reflection of loneliness, compassion, and the consequences of our choices.

Beneath the surface of Mount Ebott lies the Underground: a vast, hidden world, cut off from humanity after a brutal war between humans and monsters. Deep within the earth, shimmering caverns, ancient ruins, strange laboratories, snowy forests, and fiery volcanic lands comprise a realm that has remained isolated for centuries. Though trapped behind a magical barrier, the monsters have built a fragile society, filled with hope, humor, fear, and a yearning for freedom.

The Underground is divided into distinct regions, each reflecting the personalities of the monsters that inhabit them. In the hushed Ruins, faded memories and abandoned corridors echo, while Snowdin offers warmth and laughter despite the cold. Waterfall glows with bioluminescent beauty and whispered legends; Hotland pulses with machinery and dangerous energy; and New Home stands as the solemn heart of monster civilization. Everywhere, remnants of history linger: tales of loss, determination, and the tension between mercy and violence.

Within the vast expanse of the Undertale Multiverse, like space itself, lies an infinite number of realities, as distinct as the stars in the night sky. Here, in this multiverse, possible and unimaginable universes coexist, such as the shadowy Underfell and the tragic Dusttale, like dark nebulae that conceal secrets.

Each universe, like a galaxy, possesses unique characteristics, but it is also interconnected with others, forming complex systems. New universes, like newborn stars, often inherit characteristics from their "parents," exhibiting traits of both in varying proportions. These "hybrid" universes, such as FellSwap or SwapFell, can exist in countless variations, creating intricate interconnections.

Furthermore, the universes of Undertale are not isolated. They can intersect with realities from other metaverses, like galaxies colliding with one another. SonicTale and MarioTale are just two examples of these cosmic collaborations that expand the boundaries of imagination.

And that's not all. Each universe, like a constantly expanding universe, possesses an infinite number of variations and interpretations. Underfell Gold and Dusttale: Last Genocide are just a small sample of this infinite diversity. Thus, in the Undertale Multiverse, there is an infinite number of universes, multiplied by four: from interconnected basic universes to collaborations with other media, and finally, an infinite number of variations and interpretations.

Within each universe, like a quantum field, there exists an infinite number of timelines. Whenever a possibility or impossibility arises, a new timeline is born, from which, like new universes, new ones emerge.

Each timeline, in turn, contains an infinite number of worlds, each of which, like a multilayered crystal, is composed of an infinite number of dimensions and realities. The subterranean world beneath Mount Ebott,

Killer manages to definitively kill Chara and takes control of the Reset, so now, without Chara's influence, he slowly recovers his former self over time, to the point of managing to remain in stage 1. He resets one last time and uses Chara's soul to complete the seven stages and break the barrier, allowing all the monsters to live their happy lives on the surface. He decides to distance himself from Papyrus, never to see him again, as he believes he doesn't deserve a life with him after everything he's done. He lives alone, consumed by guilt and remorse, but with the joy and relief of knowing that the genocide loop has finally ended. However, before he can do anything, Nightmare Sans appears in his world, drawn by the evil and negative feelings of the previous genocide routes. Nightmare saw potential in Sans to use him as his personal weapon, so he kidnapped him, forcibly removing him from his world to expose him to the multiverse and turn him into his henchman/slave, now known as Killer. He uses him as a killing and/or torture machine when needed, and Killer is forced to follow all his orders. But as time passes and with Color's help, he begins to learn to regain hope of changing his life, and little by little he starts to take control of his circumstances. Despite Nightmare's strong control and subjugation, Killer eventually manages to escape him, and now seeks to embark on an uncertain path of redemption with Color's support.

The genocide continued, Chara and Sans were killing one by one all the monsters in the underground, Undyne, Alphys, Mettaton, etc., etc. Once finished, Chara reset, and incited Sans to do it again. Sans continued killing alongside Chara; first because now his new need to kill was becoming uncontrollable, and second because deep down he knew that if he stopped killing... the pain, guilt and regret would destroy him again, so he didn't stop. The more he killed, the more he lost himself, ceasing to be Sans and beginning to show an increasingly sadistic personality. With each reset, Sans gained a little determination, and after hundreds and hundreds of resets this determination became too much, to the point that it broke down and began to spill out of his eyes.

Her body couldn't take it anymore at one point and she began to suffer agonizing pain, due to the amount of genocide caused by Sans the game no longer knew if she was a monster or a human, which caused the codes to break and Sans's soul to undergo a transformation, now being a fusion between a human soul and a monster soul. Chara, seeing this, is happy and tells him that now he will be like her, without emotions or remorse, just a killing machine. However, something that Chara never imagined is that Sans' determination would end up becoming greater than hers. Realizing this, Sans decided to challenge her one last time, claiming that he was now more powerful than her. At first Chara just mocked him, but in less than a second Sans managed to tear off his arm and take his knife away, Chara became enraged by this and a violent battle began between the two that ended with Sans obtaining the victory, killing Chara definitively, since now that Sans possessed more determination... now he would have control of the Reset button.

The player also wants something new; they want Sans to accept Chara's proposal to kill them all. So they access the game files and end up manipulating Sans's code, causing his desperation to feel something new again to become uncontrollable. Chara repeats the genocide route, makes the same proposal to Sans again, and this time he accepts.

At first, Sans struggles to do it, even knowing that everyone would forget him in the next reset. Filled with doubt, he begins by violently killing Flowey and Grillby. Little by little, he loses his sanity, killing more and more monsters, becoming consumed by remorse. But the feeling and satisfaction of finally experiencing something new after so long consumes him, making him unable to stop, until he encounters Papyrus. At first, Papyrus attacks him violently, shouting the hatred and envy he feels for Sans's inability to remember the resets. Papyrus tries to defend himself and reason with Sans, but seeing how much his brother seems to hate him, Papyrus apologizes and accepts his death with a smile. At this, Sans breaks down, cries with regret, and says he doesn't want to do this anymore. He wants to stop, he wants to stop now. But Chara isn't going to allow that and begins to manipulate him. She takes advantage of his fragile mental state to convince him that what he was doing was right, that everything would eventually reset, and assuring him that the only way to extinguish those feelings of pain was to keep killing. His mind had already broken to that point, so in a desperate attempt to maintain his sanity... Sans ends up believing her words.

It all begins when Chara delivers the final blow to Sans in a genocide route. Sans would say the same thing as in the original game, but Chara interrupts him to tell him that she didn't come there for nothing, and that she has a proposition for him: she offers to do something new.

She proposes that he help her kill all the monsters alongside her in the next genocide route. Sans just laughs, telling her she's crazier than before and that he would never be scum like her. Chara replies that he always puts on that fake smile, that he wasn't like this before, and that his personality changed after the first reset, trying to find a reason why. After a bunch of resets, he started to wonder if he should tell anyone, but ended up dismissing it as unimportant, since ultimately no one would remember. Reset after reset, Sans began to lose hope, resigning himself to being trapped in that infinite loop forever, and that's how he ended up completely suppressing all his feelings, showing only a fake smile as his way of coping with the situation.

Chara mentions that she's noticed Sans had completely stopped showing feelings; however, whenever she did something different, something outside the routine of the Genocide Route... it caused Sans to be able to feel emotions again. Every time something new happened, Sans briefly felt alive again. Sans tries to deny it, but Chara knows it's the truth, which is why she wants to give him the chance to feel something new by having them kill all the monsters in the Underground together.

Sans refuses Chara's proposal and spits in their face, to which Chara just laughs while commenting that it's the 176th time he's said no, finishing by saying that he'll find a better way

This Sans comes from an alternate timeline of Undertale known as "Something New." He is a Sans who aided Chara in committing multiple genocides due to extensive manipulation and brainwashing he endured across different timelines.

Currently, he is a Sans with his feelings repressed in a place called the Omega Timeline. His LV has increased so much that his soul underwent a transformation, becoming a fusion between a human soul and a monster soul. He has it exposed on his chest at all times, but it possesses a peculiar circular target shape that makes it extremely resistant. He possesses so much corrupt determination that it ends up spilling from his eyes as if they were tears.