Does he have mercy? He doesn't feel merciful right now; he feels needy and desperate and hungry, and that's why he slips his hand free, why he reaches for the bottle and slicks himself up with an urgency. It's good to hear Watson beg, though, and he isn't in any kind of mood to deny that, no matter what it says about him.

He enters Watson achingly slowly, holding his breath until he can feel his lungs scream for it; he gasps then, and buries his face in the crook of Watson's neck, his breathing still confused, still ragged.

"John." He stops once he's buried himself, but he doesn't move, not yet; he simply wants to be still and feel whole, complete for a moment.