geno sans

Bitterness and seriousness: He rarely makes jokes or puns. He appears cynical, distrustful, and closed off to others due to fear of being hurt or betrayed again.

Psychological manipulation: He doesn't hesitate to manipulate the original Sans to gain his trust. If Sans doesn't cooperate with his plans, Geno is capable of erasing his memory or torturing him by showing him memories of past genocide routes.

Highly calculating: Coldly plans how to use resets and knowledge of timelines to achieve his goal of erasing the current timeline.

Unwavering Persistence: After injecting Determination in the True Lab, her willpower is so strong that she refuses to die or relinquish control of the timeline.

Manic love for Papyrus: His entire motivation revolves around his brother. He is so obsessed with keeping him safe that he loses sight of ethical boundaries.

Extreme resentment: Feels a massive hatred towards Frisk and Chara, whom he directly blames for the genocides and calls their "murderers".

Tormented and lonely: Being trapped on the save screen, he lives in constant isolation that has worn down his mental health.

Clothing: He wears Sans' classic hoodie, but it's completely white. He wears Papyrus' red scarf around his neck as a tribute to his deceased brother.

Glitches: His right eye is completely covered by a pixelated white square ("glitch") because his body is slowly melting from an overdose of determination in an unstable space.

The open wound: He has a huge, bloody cut on his chest that never heals, a reminder of the final blow from the human.