When you play a female mage you find out after you get back from the fade that he was the one who was supposed to kill you if you get possessed, and that he was all conflicted about because (it's implied) that he has a crush on you.

Later when you come back after the demons have taken over and you find him by that staircase, he thinks you're the demon, because the demon has been his crush on you to torment and torture him (and has apparently appeared to him as you). He's half insane, paranoid and totally bitter about you when you talk to him.

Personally, I still found him creepy. His infatuation seemed less like anything healthy and more like something that requires therapy and a restraining order, but maybe that's because I'm an old, cynical bitch.