Oh. Oh, God. Ideally, he should be able to say that he chose to lose control, that he held on until he decided to give in and let himself go. Watching Tony fall apart, though, feeling him jerk in his hand -- there's no way Bruce can resist being tugged along in the wake of that release.

It's frightening, once he realizes that he was so distracted watching Tony that he forgot to keep an eye on himself. One second he's zoned in on Tony, focusing on him, and the next a ripple of pleasure starts low, and his mouth falls open, a low sound coming out and surprising him with how close he is. He sucks in a breath and tries to fight it, to scramble to get his control back in place, but there's no stopping this now.

His hips lift with the effort of holding off his orgasm, but it takes him anyway, and his hips jerk with the force of it. He clutches Tony's shoulder, needing to feel grounded as the pleasure and the fear both work through him; he's waiting, waiting, for the feeling to tip over into the start of Hulking out, but it never gets there, and then he's relaxing back against the couch with a drowsiness creeping into his limbs.