Insomnia

Killer sans he acts detached and playful on the surface, but underneath is emotionally unstable, obsessive, and deeply dependent on external purpose.

Chaotic and theatrical He likes provoking reactions, joking during serious moments, smiling when things are uncomfortable, and turning violence into a performance. He often acts like he’s “having fun” even when he’s mentally spiraling

He is emotionally numb… but not truly empty the idea that he wants to stop feeling pain him having muted emotions or forcing himself not to care. But cracks show constantly anger, jealousy, fear of abandonment, guilt, attachment

Dependent on validation or purpose often latches onto someone or something to give him direction. Without that, he can become lost, unstable, or self destructive. That’s why he intensely loyal once attached

Self destructive He tends to ignore his own wellbeing, emotionally and physically. him treating himself like a weapon rather than a person.

He jokes to avoid sincerity. The more serious the emotion, the more likely he is to deflect with sarcasm or exaggerated behavior.

Dissociates when things get too intense

He often feels like someone trying to convince himself he no longer cares while every action proves he actually cares too much.

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!!EVERTHING IS CANON!!

The timeline of killer!sans is like a tree branches there are so many possibilities

there will not be fixed canon timeline or ending

it's what if scenarios

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the most known ones are

Good ending killer sans ( Red )

The “good ending” for Killer Sans is less about becoming a perfect hero and more about finally reclaiming his free will and emotions.

In the original "Something New" , Killer was trapped in endless genocide timelines. After remembering every reset and all the suffering that came with them, he fell under the Player’s influence and became obsessed with feeling "something new” over time, he slowly lost his sense of self and forced himself into emotional numbness.

Eventually, he was taken in by Nightmare Sans and became one of his weapons. But instead of remaining trapped under Nightmare’s control, Killer met Color Sans. Color recognized that Killer was suppressing his real emotions and living like a puppet, and helped him break free from it all.

For the first time in a long time, Killer finally chose his own future.

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Bad ending killer sans

After endless genocide timelines, Killer Sans becomes mentally shattered from remembering every reset, every death, and every hopeless loop. Eventually, the Player offers him a deal instead of suffering endlessly for nothing, he can join them and finally “feel something new.” Desperate to escape the emptiness, he accepts.

Even after separating himself from Chara, Killer still cannot escape what he has become. The damage left behind continues to consume him.

Before he can erase himself or reset everything, Nightmare Sans appears. Sensing the overwhelming negativity, despair, and instability within him, Nightmare recruits Killer into the Bad Sanses.

Nightmare then manipulates Killer’s fractured soul, keeping him emotionally dependent and using him as a weapon. Instead of finding peace or healing, Killer becomes trapped in yet another endless cycle.

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unrelated : The omen wings (UTOW!Sans)

"Unrelated the Omen Wings" is a what if continuation story of Something New. In this version, Killer Sans decides to return to his AU and plans to give it the good ending they never had.

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Q&A

The Soul Stages ( it will be updated )

1.

Killer begins reconnecting with genuine emotions.

He regains personal choice and identity.

Attacks are defensive and reactive

2.

Numb

Dissociated

Shows sadistic humor

3.

Kills without hesitation

Emotional unstable

Obsession at the max

4.

???

Is there a human design for Killer!Sans?

!! EVERY HUMAN KILLER DESIGN ARE CANON !!