Sherlock had taken up piano.
It was all John's fault, really. In order to help Sherlock kick his disgusting smoking habit, the blogger suggested that Sherlock pick up a new hobby, one he could do in between cases. Naturally, Sherlock chose to teach himself piano. John was wary of this at first, because he thought it would mean endless hours of careless plinking on the instrument. In retrospect, he should have expected his detective to be a fast learner. By the second day of obtaining and installing a baby grand in the sitting room, the world's only consulting detective was playing advanced pieces from classical to contemporary.
It was sexy as hell.
The detective floated his pale hands over the keys as if he were made of water, flowing and graceful. He adopted a peaceful aura when he was playing. He became a whole different person, and it was quite beautiful to watch.
Often, John would be dragged from his blogging, his detective insisting, "John, look what I can do," like a child. Sherlock would then play an intricate piece, and John would just gape at him, open-mouthed. The detective would stand and bow and the blogger would clap and hoot enthusiastically. It was quite enjoyable for the both of them, and, Sherlock had stopped smoking.
So naturally, when John walked up the front steps of their shared flat and heard his detective playing an upbeat melody, he couldn't help but smile. He was taking the stairs two at a time when he noticed that this song was not one he knew. He took the stairs much slower then. It was almost as if… no. Sherlock couldn't have written this.
Listening more attentively, the blogger noticed that the piece was quite complicated, more advanced than he's ever heard Sherlock play. It had a distinctive right-hand part and a separate-left hand part that played around each other, in a sort of conversational manner but yet still in harmony. That's when John's throat thickened and his eyes got hot. Because not only had his detective written this piece, but he wrote it about them. It was uncharacteristically sentimental of him.
John couldn't take silently eavesdropping anymore and burst into the sitting room. Sherlock stopped playing abruptly upon hearing his partner enter the room, much to John's dismay.
"No, keep playing," John insisted. Sherlock just shook his head sheepishly. "Did you write that?" Sherlock nodded. "About us?" Sherlock nodded again. "It's beautiful," John said, wiping his eye.
"You're beautiful," Sherlock said, crossing the room to kiss his partner. John's mouth parts habitually and Sherlock deepens the kiss. Before long, they are both lightheaded and reluctantly let go. John's eyes were still leaking, so he leaned his head on his detective's chest. All he could think to say was, "Thank you."