"I don't know, yet. When I decide, I'll let you know." Bruce slid a hand back through his hair, knowing it was admitting he had no idea what to do with Loki. In reality, he was torn between telling Tony that Loki was here and letting the decision pass to someone else or just calling SHIELD himself and telling them he would let the Other Guy out if they decided to hand Loki back to Asgard.