I think he's supposed to be the true villain? From my understanding of other spoilers he's the "most powerful emperor in recorded history" (in the beginning, when Lucas was learning what had happened and mocked the tales of Lucas being a faithful servant to Aethernitas.
He's the guy who broke into the tower and took away all the magic within, later on brainwashing Claude's brother. It's why their eyes switch colors in the previous chapter.