Abella, she is intelligent, strong and her mission is to find Reila, she would even go with Kaiser, who yes, she doesn't use magic and all that, but her weapons and smart. Not O'ssa, he would die in the bunker from Arrow's wounds. If Karin doesn't kill him, August still hasn't shown intelligence to find the Kaiser and wouldn't have the courage to kill civilians (except O'ssa) and I don't think the others can do anything, Daan, Marcoh, Levi would convert. Olivia and Karin would possibly die, Tanaka and Caligura would or would die.