Steve can feel the shift as he throws his head back, and he opens his eyes again, looking at Tony. He looks like he's drowning in it, carried away in sensation, and it's one of the more beautiful pictures Steve has ever seen. He makes another little sound, less deliberate, more of a whimper of approval than a hum, and his hand skims the planes of muscle and bone across Tony's hips and belly.

He's trying to go slow, but it's easy to get carried away with this kind of encouragement. He bobs his head again, pulls back slowly with a slick, wet noise, and then sinks down again with a sigh. There is no rush here. He could happily keep this up for a long while, maybe even longer than Tony could take.

His one major regret is he can't talk to him while his mouth is this occupied. But maybe that's for the best. They can let physical reactions speak for the both of them.