After Frisk did many genocide routes and resets, sans remembered that and he decided to do his own genocide route by killing friends. Even his brother.. only to kill human.. his abilities are firing gaster blasters at enemy, he can summon stolen attacks toriel flames, undyne spears, and asgore tridents. After he killed his brother Papyrus, in waterfall he showed up in phantom form sobhe can help dust sans. He can be sad sometimes when he remember about old memories...