"Of course." He would give John anything, everything.

Sherlock licked another stripe, but this time he held it at the tight little pucker. While his hands held John's arse cheeks open, he pressed his tongue against the hole. At first, it didn't want to give, but after pressing in and relaxing a couple of times, John started to relax, and Sherlock felt the muscles open.

He took the opportunity to push forward and press his tongue inside of John. "Ohhhhh..."