Team Anna!
Isaac was already fully wolfed, his senses sharpened as much as possible, claws prepare to sink into anything that got close. He doubted he'd be most effective here, Elsa and Loki had magic, but at the very least he could make sure nothing got past anyone to get near Anna.
Stiles was gone, and Anna was pretty much all he had left here, if he had to tear something apart he would. "So how do we do this?"
He wasn't a leader, not in the least, Isaac had learned pretty well by now how to take orders and make them work. He'd be able to go with whatever the others decided, especially since they were all here to make sure Anna wasn't hurt doing whatever it was she needed to do to stop these demons coming in.