I got this idea from the comic up above.
It can be whatever scenario.

Demons: Hanzo, Genji, Cassidy , reaper, Sombra, Widowmaker, Moria, roadhog, Ashe, doomfist, And Junkrat.

Angels: Lucio, Mercy, Pharah, Ana, tracer, symmetra, Bridgette, D.va, Zaria, and Mei

Halflings (half Demon and half angel) : Airi, Soilder, bastion, Torbeirn, and Winston

Your oc can be in which ever.

Airi keeps a blindfold on to calm the demon inside of her. But she won't hesitate if she need to take it off. Once she does her demon side shows.