Sherlock stood at the door of 221B. It was one O'clock in the morning, and the orange glow of the street lamps gave the street an eerie atmosphere. He knew that John would be asleep by now. He never left the flat after five, and would draw the curtains of his bedroom around seven. Sherlock had been watching the flat for months now. He hid in the alleyways on the street, watching from the dark as John came and went. More often than not he wouldn't go out at all. Weeks would pass before Sherlock caught a glimpse of John again. Of course, he couldn't stay near the flat all the time, so maybe that had something to do with it. Either way, it always made Sherlock happy to see his friend functioning at least semi-normally.
He missed John. He missed the first friend he had ever had; that presence that he could always rely on. On countless occasions he would walk up to the door in the dead of night, when no one was around to see him. This was one of those occasions. He found it so hard not to knock on the door, or to just let himself in (he still had his key). He wanted nothing more than to go inside, walk up the stairs to the flat and just go back to the way things had been before. Before Moriarty, before all these games. Most of all he wanted to see John. He knew John would probably beat the crap out of him when he found out, but the bruises would heal and so would John, in time. They could go back to the way things were, solve crimes together again. Sherlock reached out to touch the door. All it took was one knock.
But now was not the time.
Eventually, Sherlock would be able to see John again; be able to laugh with him, walk the streets of London together. But things still had to be done before then; things had to be set right.
Sherlock lowered his hand from the door. Then, tears glistening in his eyes, he walked away from his beloved friend and melted back into the shadows.