Archelaus

Once the king of the demon realms, Archelaus was the first (and thus far the only) king to step down rather be overthrown in the old fashioned rite of succession: a fight to the death. It wasn't for lack of power, mind you, but he'd grown tired of the time and responsibility required to keep the balance between realms. For a time, he went about his own business, enjoying his freedom and living about as peacefully as one could in a realm where power and connections determine the pecking order. When a cocky, arrogant upstart managed to win the throne from his successor, though...well, he had to go make sure that this moron wouldn't break the balance. Turns out this moron is actually surprisingly capable though...so he's remained as an adviser to have a front row seat to the way this king's reign will play out.

Fun Facts:
-If his mask is on, it's ass-kicking time. Run.
-He is one of few demons of his caliber that go about in their full form full time. He has a human form, but only for when he has no choice but to interact with mortals.