Sherlock loves playing the violin, it helps him relax and allows him to think clearly, he usually does it by himself but not now, his flatmate had a nightmare, they often have them, it's not new, Sherlock knows, he's not stupid he can tell when they wake up started and how they always walk out of their bedroom to get a glass of water looking uneasy, so in those moments he likes to play the violin for them too, of course he would never openly admit that he plays the violin to his flatmate