Watson gave a long, savouring sort of groan, his hips bucking slowly and entirely involuntarily towards Holmes. He brought his other hand into Holmes's hair, and clutched tight with both hands, some tiny remnant of control that he could manage to keep. This was perfect.

"Christ, yes." He let his eyes close, to better to savour the moment, the sensation. He slid his hands over Holmes's hair, while he panted at the effort of not crying aloud --- at least not any more than he already had.