Sometimes, when Sherlock was gazing into his microscope, John would set a cup of tea down next to him. Without looking, Sherlock would lift the cup and take a sip, then put it back down again. It might be the last time he touched it. Or it might not.
Sometimes, when John woke up, he found the coffee had already been put into the maker and the water measured. All he had to do was press the button. It was usually way too strong, or way too weak, or something else. But John would drink it anyway and never say a word.
Sometimes, when he was lying on the chesterfield and thinking, John would look at him for a moment, and then let him be. Then Sherlock's eyes would slit half open, and he'd glance over to John and smile his tiny smile.
Sometimes, when he needed John's attention, Sherlock would reach out and lightly touch him on the wrist.
Sometimes, when John needed reassurance, Sherlock would briefly link his fingers with John's.
Sometimes, when John was frustrated with him, he would look up and see puzzlement on Sherlock's face, then contrition. It always reminded him of a puppy who wasn't quite sure what he had done but knew there was a newspaper coming. He was never quite able to bring the newspaper, after that.
Sometimes, when he'd really blown it, Sherlock would lock himself in his room and not come out. Not even for John. The violin was silent on those days.
Most times, the flat was filled with violin music. When John was sad, it might be something melancholic, comforting. When he was angry, it might be something placating. When he was happy, it might be something cheery or modern or even silly. (Once it was Bolero; John hadn't known quite what to make of that.)
Most times, when John lay awake at night, unable to sleep or afraid to, the violin downstairs would play a lullaby. John never asked about it.
One time, John had come out of a horrible day at the surgery to find that the weather had turned suddenly, and him without his jumper or jacket. But there was a cab waiting for him at the door. With his jumper. When he'd got home, he'd found a fire in the grate and hot take-away in the kitchen, next to the remains of the stew that Sherlock had attempted to make until he lost track of time only to realise that it had boiled away and burned. John had gone and got a towel, and dropped it over Sherlock's sopping curls and ruffled them dry. Sherlock had glanced up from the microscope with a contrite little glance and John had stared for a moment, incredulous, then shook his head and grinned and gave him a grateful smile.
It wasn't that Sherlock didn't talk. It was that John had learned to listen.