Gren is definitely going to be taking the fight to these robo-assholes. He's a pretty heavy hitter when he's out of glamour and is probably close to the same weight class as the Null, so he'll want to be wherever the fighting is thickest. He might hang around Lup and Taako for a while because, hey, he owes them a favor or whatever. They cooked dinner for him.

Also I am 100% certain that Gren's going to get badly injured in this whole shebang and considering having him just get straight up killed, so that's a thing.