He set down the remaining box with a quiet groan of protest from his back. "Captain America," he answered immediately, and then coughed, giving a slight frown of embarrassment. "...It depends what kind of powerful you mean. They all have their strengths and weaknesses. Physically strong? Would have been Hulk or Thor, but without them around it'd probably fall to Iron Man or Cap." Not that Stark was, strictly speaking, an Avenger any more.