Summary: Sherlock thinks that he is incapable of friendship. He's wrong.

AN: I have just discovered BBC Sherlock, about a year and a half after everybody else. I saw the Reichenbach Fall after Christmas and was immediately hooked. I have not seen all the other episodes so this story may well be contradicted by canon. I'll call it AU anyway, for the ending, Spoilers for the Reichenbach Fall.

AN2: Thanks to Lady Heliotrope for telling me about the relevant scene in the Baskerville episode. I have now got hold of that episode and watched it. This story has been revised to include it.

Sherlock lay on the sofa with his hands steepled under his chin. He was analysing friendship.

Sherlock knew that he was not normal. So did everyone he met. It was true what everyone said of him. He was a freak, with no friends. But it was not through choice. However hard he tried, he had never been able to deal with social interactions.

Once, in his youth, he had made a study of friendship. Following up every word associated with friend in the thesaurus, he had tried to put what he read into practice. He quickly learned that textbooks were totally inadequate for teaching yourself how to interact with others.

But, after years of isolation, John had come into his life. For the first time Sherlock had felt admired for his mind, rather than scorned. He had felt at ease with John, and felt accepted by him, despite his many eccentricities (faults). He had thought that John felt the same. He had thought that their relationship qualified as friendship.

Sherlock was proud as he introduced John as his friend to Sebastian. It was good to show Sebastian that he was capable of having a friend. He didn't need to know that John was his first ever friend, and that he had only known him for a few weeks.

But that pride had lasted only a few seconds. When John bluntly contradicted him, Sherlock did not let any of the confusion he felt show on his face. He merely pushed it into the back of his mind to be analysed later.

This was later.

The first thing that Sherlock considered was the definition of colleague. He had introduced John as his colleague, the first day they met. He had not meant friend. But could a colleague mean friend?

He came to the conclusion that, in this case, John had most definitely meant that the word friend did not apply. He was telling Sebastian that he and Sherlock worked together, but were not friends. Clearly he had failed, yet again, to grasp the true concept of friendship, and had wrongly attributed it to himself and John. He acknowledged to himself that he did not understand where the mistake lay, but a mistake it had obviously been. Frustrating though it was, Sherlock had to accept the fact that he would never understand it. But he could abide by John's wishes and, in the future, introduce him as a colleague rather than a friend.

Having resolved the matter in his own mind, Sherlock was surprised to find that he felt a lingering sense of disappointment and loss over the matter.

b_b_b_b_b

Over the next year, Sherlock was always careful to introduce John as his colleague. If anyone made an error, and spoke of John as his friend, he was quick to correct them. Except for Mycroft, whose description of them as 'pals' was so obviously sarcastic, that it needed no correction. For reasons that he didn't completely understand, Sherlock found that he preferred to correct them himself, rather than wait for John to do it. But each time it happened, Sherlock would find himself left with a totally illogical sense of longing

There was one day when things might have changed. While they were in Dartmoor, looking for the Hound, John, for the first, and last, time, told Sherlock that he was his friend. The timing was dreadful. Sherlock was in the middle of a meltdown, reacting to the drugs he'd been dosed with, and practically manic because his finely tuned senses were telling him something his brain could not come to terms with. He was a wreck. Instead of reacting with happiness to John's statement, one that should have meant so much, he let the built up frustration of the previous year take over. He snapped back what he had believed for so long. "I don't have friends." Even then the situation might have been saved, with his apologies. But Sherlock chose to cruelly use John in his experiment, going so far as to trick him in the guise of apologising. John did not react well. Once more Sherlock was confronted with his inability to understand how to be a friend.

Then came Moriarty and his threats. Sherlock was tempted to point out to Moriarty that threatening his friends could not possibly have any effect on him, as he did not have any. But Moriarty seemed oblivious to this, and continued to act as if Sherlock had friends. And here the two of them were; on a roof, with Sherlock given no choice but to jump, if he wished to prevent his acquaintances being shot dead. It was not the sort of thing one would do for an acquaintance, but Sherlock discovered that he was not normal in that respect either.

He stood on the edge of the roof, phone in hand, ringing John's mobile. Sherlock could see him, down on the ground, looking up at him. He played out Moriarty's script, as instructed, declaring that he was a fake, trying to convince John.

"This phone call. It's, .. it's my note. It's what people do, don't they? leave a note?"

In the final moments, he had to say it. He wanted his last words to John to be his own, not Moriarty's. "And John, I want you to know that I regret that we were not friends. I had thought, " he hesitated, "hoped, once, that we could be. It would have been, ..., nice."

Pausing briefly while John pleaded with him not to jump, he closed his eyes. Gathering his courage, he whispered "Goodbye John." Then, dropping the phone, he stood at the edge of the roof, and let himself fall.