Sherlock threw his head back, it hit the back of the couch with a dull thud. Oh how he wanted to thrust up into John, but he didn't want to choke his husband. He knew that they had to be very careful for John to not overexert or hurt himself, so he held back- biting his lower lip to both stave off a stupidly short time before orgasming, and thrusting up and fucking John's mouth.

The pain of John's Demon nails- still a bit sharp even in human form, just sent him spiraling further and further into pleasure. This was going to be a very short sucking session before he couldn't hold back any longer, he knew.

Sherlock threaded his fingers in John's short hair and pulled softly, not enough to hurt, just to encourage.