Oh, he quite likes that. The fingers in his hair feel rather good, very encouraging, and he pauses to simply enjoy the feeling of it for a few long heartbeats. While he's certainly not Tony in terms of muscle, and there are spots that are less than lean, he is probably more muscular than most scientists and doctors, for certain. The pudge on his belly only gives him a softness he needs, right?

The kisses, more like presses of his lips, are soft, shifting, feeling the way the muscle and esophagus beneath the skin move. When he feels the pulse bright under his mouth, he pauses, counting, before pressing a heavier kiss there.

Sorry for the glacial pace, Tony.