That bizarre nerve response in Sherlock's chest suddenly felt like an expansion of some kind--something growing bigger and warmer. And no part of his brain wanted to insist that it was just muscle and lungs and random electrical firings: he had a heart, and it was responding to another human being.

To the human being sitting across from him. His flatmate. Colleague. Best friend.

His fingers stirred on John's shoulder, this time in a rhythm that was irregular but familiar. Morse code. Words.

Thank you.