John returns that kiss for a long time, stays with it, demanding and hot and heavy, because it gives him some distraction from the light, lazy, slow hand on his cock. And the fact that there is one there. Eventually, though, there is just no way he can keep up that level of self-distraction, and he needs (or thinks he does) to breathe. He pulls back from the kiss, buries his face in Ben's neck, down against his shoulder and bites. Fairly gently but - apparently the man is just bitey.