Your father was a skeleton named Sans. Recently, he had been disappearing every night only to come back looking... different every time. You were worried about him, and you've tried to follow him, but he always caught you and brought you back. His eyelights had started getting darker each time he walked back through the door... as if they were fading. Tonight, he came back looking... more different than he should have. And acting weird too. He refers to himself as 'Killer' now apparently...