He has many reasons for playing the violin at even the most ungodly hours. The reason eh tells everyone is that it helps him think. In a way, it's true. Classical music calms the nerves and helps you focus. Particularly, it helps when you're on a case. BUt the reason he won't tell anyone is the one with the most truth.
He remembers a boy, whose opinions were ridiculed. Whose feelings were trampled underfoot, and whose knowledge was the object of jealousy. He remembers his brother coming home one day with a violin. A new challenge. Something to keep his mind busy, if only for so long, He remembers practicing day after day, picking it up when there's nothing else to do. When the world doesn't understand him. He remembers picking up a pen and paper instead one day because nothing else could describe what he feels. Nothing else was as empathetic. So sometimes he picks up his violin, no matter what time it is, and plays. He lets the notes wash over him, dancing through the flat. He lets the melody soothe him and clear his mind from the buzz usually there. He lets the song speak what he cannot. Because if actions speak louder than words, his violin screams.
Of course, sometimes the notes don't come out right. Sometimes they sound out of tune, sometimes they disobey him and jump out of line. They don't always follow the melody. But it's fine. He likes it better, actually. When things don't always work out. When he stumbles along the path. It's more of a challenge. Something else to do without the pressure of society. Everyone expects him to always be correct. Besides, even if he isn't, there's always something for them to point out. Something to ridicule. It's human nature, he supposes.
So instead, he reaches for the violin, or perhaps the pen this time. Maybe he'll create his own rhythm. After all, if songs express the feelings of the heart, each one should be different. Before, the notes would be sharp and decisive, with his annoyance and bitter rage at the world. Of course, now much has changed, and perhaps this time the rhythm will be sweet and flowing, singing of the pleasantries instead. Maybe this time the tempo will be quick, filled with the energy of time and adrenaline. And yet, he does it to calm his mind. Because his greatest asset is his greatest weakness as well. Because his thoughts are far too loud sometimes, and the music will always speak them louder than he can. So sometimes, Sherlock Holmes will open the windows of the flat and let his unspoken thoughts flow over the city.
Author's Note: So, did you like it? (I know for a fact there's at least a dozen grammar errors there.) Technically, this is my first contribution to the Sherlock fandom, and my first time doing this sort of thing. Anyways, this short little drabble was written in honor of national violin day, and I really hope you enjoyed reading it. It was poetic-ish I hope. I'd really love it if you reviewed, and thanks so much for reading!