A demon? [ she laughs at that. ] No way. Humans can't turn into demons, for one. They're more... abstracts given form. They don't have souls.

Sam became a fiend. Immortal, powerful, inhuman, but still himself in every way that counts.

The Harvelles and Bobby Singer were just three more casualties on the quest your brother was undertaking. Demons took the girls. Iscariot killed Bobby.