You've met Phantom. You've met his father, Abaddon. But, you haven't met the other two sons of the Lord of Darkness, Akuma and Birash! Akuma and Birash are the younger siblings of Phantom, Birash being the middle child and Akuma being the youngest, as well as the most immature. Both younger demons are Prince Demons, though are quickly on their way to becoming King Demons like their older brother.

Birash tries to act like he's the most mature and the oldest, though usually fails and still gets dragged into plenty of situations with Akuma. Said demon, while not technically naive, is incredibly immature and somewhat irresponsible, nothing short of being a jokester and prank master. Though he may seem to lack the ability to be serious, if the time calls for it, he can be next to Phantom level seriousness. Even though the three of them sometimes don't get along and may even fight, at the end of the day, they're brothers that look out for each other and would destroy worlds to express just how much they have each other’s backs. (not that they would ever verbally admit it, of course).

Phantom is on the bottom, Birash in the middle, and Akuma is the one about to make them all fall over.

(Reference image found here: https://www.deviantart.com/mugges/a.....uad-594944134)