You know what confuses me the most? That some people can't tell when they've been virused.
It isn't hard to look on your past actions and think, "I would never have done this." You don't need an expository wardrobe change either. Or an opposite twin running around.
Speaking of which... it's very convenient not to have one, isn't it? I'm sure I would have been impaled by now in the worse way, had this been the third time Issei Ryudo picked up a doppelganger. But frankly, no one's going to do anything to the body the precious beloved Issei has, so I have free reign for as long as the virus lasts.
Now, dance like puppets for my amusement.