Michael
Yeah. I don't know if you ever heard of the trials to close Hell, but curing a demon's one of them. Not fun.
More than one reason. Those troublesome hellhounds you were telling me about, I'm going to siphon their energy to recharge my own. Not much further I can do without access to Hell, or the ability to kill innocents, and I'm actually happy defying the stereotype of a heartless demon. Even if I don't technically have a soul.