John bites his own lip to avoid making any silly noises just so that he can properly hear Q's. This boy clearly knows what he's doing on a great many levels -- and those little whimpers are just one of them. The way he moves (but just doesn't, also) is another.
It doesn't stop John wanting more though. He's a bit greedy, but he also has it in his head to see Q more undone than all this -- there's something very appealing about the idea of seeing what he might be like where there are no plans in place. More, more, more. For now though, he mostly behaves himself -- digging half crescent moon shapes with his nails into Q's hip bone with one hand and using the overly slick fingers of his other to take hold of the younger man's erection (it's always the thin men, isn't it, with the most impressive bits?).