Nebulous
Legend
Yeah. There seemed to have been a fall from grace story there. Dungeon Master did refer to him as his son.
In fact, Tiamat was chasing him around the multiverse. Perhaps he had stolen part of her power or aligned with one of her enemies.
I did not know either of those things. Especially being a "son" of Dungeon Master. Wow, all kinds of ways you could use that stuff.