A threesome. Nothing new, only... that's Rose: soft, warm and inviting, the Doctor beside her. The muscled frame matches Jack's fantasies, but it's the relaxed, unguarded face that makes him hard.
Rose's ragged gasps become whimpers. The Doctor's eyes turn black as he explores her. She reaches blindly for Jack, hears his muffled groan. The exquisite torture doesn't stop.
The Doctor is slowing Time. Desire is endlessly prolonged. Jack's going mad; Rose sobs. The Doctor suffers too, controlling Time, but not himself. Finally. pleasure sweeps them over the edge towards release. The Doctor grins wickedly; pleasure can also last forever.