Fem! Murder Time Trio

After her skull being broken and apart of her magic being snatched by the now insanely violent Undyne, something within Horror changed after that incident. Horror claimed a new rule created where humans who fall down are to be consumed for survival. After this Horror was no longer the joyful skeleton she was once. Despite the rule Horror never eats anything, especially humans, for 7 years which gnawed all the kindness out of her, along with all of the sanity thrown on her brother who fell for her trick to eating a piece of flesh in a spaghetti meal in order to save her from starvation and convince to not go on a hunger strike. After many years of hunger Horror is seemingly bored of everything, but it has damaged her psychological state severely, she now enjoys psychological humor and enjoying every bit of Aliza's screams. Whether it be Papyrus's puzzles or the hungry people of Snowdin or even herself torturing Aliza, she has no sense of morale of care for any right or wrong her jokes have changed from annoying yet funny to dark, insane and sadistic reflecting her attitude. She loves to decapitate human heads for fun (usually using them for "head-dogs"). Although, she gives himself boundaries, which one is never eat a human, despite being the one who gave out the rule, and tries to prevent Undyne from finding out of Aliza's existence. She also shows regret and sadness over realizing she almost gave into her hunger and tore out Aliza’s arm and almost ate it, only for Papyrus to stop him via letters to tell her not to eat anything that moves. This could somewhat prove that the original Sans is still somewhere inside the insane and starving skeleton. For now all other AUs view her as an insane yet tragic figure who is merely a small piece of what she was only seen to Papyrus and only her.

Before the human arrived in the Underground, Dust was more of a lazy and friendly skeleton who would often make jokes. She would go to Grillby's for a good amount of time and was very caring about her brother, Papyrus. However, after the human reset and did numerous Genocide Routes, one day due to unknown circumstances, Dust suddenly remembered all the Genocide Routes. This changed Dust and made her kill other monsters for LV, even going as far as killing her own brother. After this, Dust became careless, psychotic, and obsessed with killing the human, doing whatever it takes to stop them. She has also shown signs of schizophrenia and can go through episodes of depression, judging her actions as futile. She is a desperate, broken person who has gone too far and done too much to forgive herself, and doesn’t see much use in stopping now.

1st Soul State: In her first soul state, Killer is more like her classic counterpart as she begins to re-obtain her emotions and feelings, showering her with guilt for the sins she has committed. Due to her shifting personality and past actions, she doesn't consider herself a Sans anymore.

2nd Soul State: In this stage, Killer's emotions have faded quite a bit, and she is more willing to hurt.

3rd Soul State: In this stage, also referred to as her crazy stage, Killer is fully emotionless and will attack and kill everyone and everything that gets in her way.

4th Soul State: Not much about this stage is known as Killer completely refuses to talk about it. Her hallucinations seem to worsen in this state, but she keeps the murderous intentions of stage 3 and the sanity of stage 1.