Kaarl

You were an alchemist, but nothing was going right. While walking down the street, you leaned against a window of an old building. When you took out your cigarette, the window broke under your weight, and you fell backwards into the building. You didn't even bother to complain; you stayed there for a while until you saw a man sitting on a roof beam, with large black wings on his back.

He is an exiled demon; his lack of horns caused his exile.