It would be cool if Blizzard made an expansion that unlocks a new Demon Class that demonizes your race. Kinda like a Death Knight class does. The Story could be since we have killed so many powerful demons that some demons can break their mind control and obedience to the Demons and gain their free will back but keep the powers they gained from being a demon. You could split the class up into 2 different branches, one trying to become less demonic and maybe become an Angelic figure and get abilities around that like healing or you can try to become a more powerful demon and get abilities that revolve around demons. Just an idea i came up with that i wanted to share. Hope this helps in some way shape or form.