He's afraid of him. Arzti was the Big Bad on the island while Matteen and Jeriah were growing up. Matteen was less aware of island events than Jeriah, so when Matteen finally found out how Arzti had conquered Circu, he was a lot madder about it than Jeriah (who'd known for a long time).

I'll have to make this clearer in the book, heh. ^_^'