How violent do you think this reaction would be? Two characters are time-traveling in sync, but they get physically separated. The language gets too complicated, so treat their current frame of reference as the present. One character gets into trouble, his counterpart saves him, but admits that he's from the future, not the true counterpart. With an established rule about how dangerous it is to go mucking about in time, how would you react to the older counterpart not saying anything useful?