"Captain." With ash coating his shoulders and leaving each of the clean, sharp lines of the joints and ridges of his armor in framed in dark contrast like jagged reminders of his rigid shell and the purpose for what it was built, Iron Man returned to the ground with the flat greeting, forcing the dust that had just come to settle up into the air again to hang as a dark cloud. He did not advance, but the murky glow of his eyes and heart were turned towards the Avenger, and after a moment he said, "Your assistance here will not be required."
Not only did Iron Man have this situation entirely under his control, he knew Captain America would attempt to take that control from him. Tony's morality was too strict for efficient functioning and kept him from performing to the best of his abilities, and in studying Captain America, Iron Man had found him even more intolerably restricted. The Avengers' methods would have to be overriden, and Iron Man could not trust any of them to function ideally without testing. And Tony's conflicting, powerful reaction to the appearance of his teammate was a nagging distraction that Iron Man did not further wish to tolerate.