Umm.
I thought that Ozzie's decendant became the leader because Magus dissapeared.
When Magus came back and faught Ozzie, Magus became a traitor, and the whole consept of Ozzie being Magus' lacky made it seem like Ozzie was like Magus so Ozzie's decendants became trash, and those nice Imp Mystics became nice to humans and the leaders of Medina.