It takes just about every ounce of patience Bruce has not to flip out here and now. This is what he and Tony fought over that finally led to Bruce pushing him away, and while that had nothing to do with the reason for their time apart, it still wasn't something they ever really went back and resolved. He inhales through his nose and exhales through his mouth, as subtly as possible, and he closes his eyes for a few seconds.

"Because nothing can go wrong and accidentally give you super speed or fire breath or..." He lifts his eyebrows. He can't say monster. He can't really imply the Hulk is bad, can he, without alienating Tony. "Any unexpected side effects?"