Now that they were both spent, why didn't Harry simply push him away, scramble out from under him and gather his dignity once more, or what remained of it?
Why was he holding him even tighter, as if he were reluctant to release him, wanting to keep him inside of him for as long as possible, retain the sensation of their union for as long as possible.
Could it be that he actually cared about the Slytherin? What strange new world was this?