I think he's said before that the priestess ended up as an essential hero in his first playthrough, so it's probably not her, unless we're having a redemption+recruitment chapter next.
I love this arc. I don't care how long it will take, we're getting to see all these characters get better. And showing improvement, no matter how small, is what world trigger has been about from the start.
Eye of Command only works on targets with a lower Magic stat than him. So up until Jr's Elemental Disintegration landed it wouldn't have done anything.