Jack bit down on the Doctor's shoulder, just hard enough to leave a mark, shifting his grip so he could brace his weight better, moving faster and harder, angling to hit the spot that made the Doctor squirm and gasp.
The Master flexed his fingers in the Doctor's hair, pulling away a moment to lean a bit further, kissing Jack fiercely, possessively. Held onto him, and returned to the Doctor, his trousers uncomfortably tight, but unwilling to move one of his hands to relieve the ache. All but lost in the sensations that he was catching and reflecting back.