The Folder
I've seen some fics about Sherlock's Mind Palace, so here's my contribution! Oh: This fandom belongs to Doyle, Moffat, Gatiss, and any other Sherlock Holmes-affiliated people in the world. I just love Sherlock; so I play around!
Summary: He has a folder. Just one folder that he never touches.
He always says out loud that he has a Mind Palace, but it is more on a dark corridor. At the end of that corridor there is a bookshelf. The bookshelf is made of oak, and there are five shelves. On the top shelf he keeps the folders of four people. The next one contains Other People, while the last three contain things like 'Rare Poisons from South America', or 'Telling the age of fingernails'. He adds folders when necessary, of course.
When he met Irene Adler, he added a new folder with her name, the date he met her, and any information he had on her. But he deletes. When they first met; he kept the Important things. Information, how he out-smarted her and, in turn, how she beat him. That was important; don't make the same mistake twice. The lock combination to her safe, the password to her camera phone, his almost-blunder, and things like that he kept.
Mycroft has a much larger folder where most of the things are not deleted. But small things; the time he administered 'The Talk' to Sherlock, a few useless observations, some of the Incredibly Dull cases, those are gone. Charts showing his steady weight gain are gleefully kept in front, while their childhood memories (the bittersweet ones, as they all were) are shoved roughly in the back, where at times he pulls out to stuff unceremoniously back in or at times look, fingers dancing over softly at the sweet childhood innocence he had carried and then placed carefully (ever so carefully) back in until the next time.
Jim Moriarty has an even larger folder than Mycroft; full of diagrams and webs and videos of the pool, the courtroom, the roof. Sebastian Moran is filed under the same folder in a sub-category. After all; Moran is nothing without Moriarty guiding him. Sherlock looks at this folder in disgust; the man who caused him pain (so much pain) and feelings well up inside him and Sherlock slams the folder (never gently) shut and places it back with loathing.
The next shelf (the 'Other People' folders) contain only a couple of folders, some small and some large.
His cases, he keeps the information, but the useless trivia he throws. The Hound of Baskerville he got rid of his sugar hypothesis. That is gone, like it never existed. So are so many others. His Unsolved cases are shoved in a slightly dusty folder which he may pursue later and puzzle over.
His acquaintances—Mrs. Hudson, Molly, Lestrade, Angelo—he tucks away in a corner where he stores things like their health, his newest observations. There are several other folders—one for insults, one for his sock index, one for his connections and where they are and what they're up to. These folders are small, though, tucked under the more Important folders.
But one folder has everything, everything he observed, deduced. Every conversation.
John Hamish Watson.
The solider that walked into his life. Sherlock has kept everything; he can't delete a single thing. He has everything from when they first met, keeps a list of the times John complains about needing milk, a chart to show how annoyed John is with him (At one, which is not very annoyed, John's eyes twinkle and his lips twitch. He puts on a show, but stance is relaxed and hands are folded. At ten, angry, John's hand twitches towards where his gun ought to be, his eyebrows are mashed together, and his voice is shouting. It is then Sherlock takes him very seriously.) The amount of dates John has (but never the names), the songs Sherlock plays on his violin that John likes, the experiments that get under his nerves the most (So far it's a tie between the slaughtered cow carcass filled with jelly in the tub and the maggot-infested penguin in the freezer.)
And Sherlock can't delete anything.
He's never really tried, either. John is just too interesting. There is no other word for it. John is fascinating, so much more that Mycroft, more than The Woman, more so than even Moriarty. Moriarty tried to get his attention through the games, the shoes, the Prince case, the painting. And he would have gotten his attention, too, if he hadn't kidnapped John. With John there, covered in semtex, Sherlock could only put up a small portion of his brain to answering Moriarty. The rest of it was firmly fixed on John. He could tell every single knuckle was bruised from multiple punches because John kept rubbing them slightly. He could tell everything that had happened to John.
John had gone down fighting, only to wind up covered in bombs.
But John had fought for Sherlock, had warned him through blinking (Morse code, brilliant!) that Moriarty was here and Sherlock should leave. That Sherlock should leave. No 'Get me out of here', no 'help me', just Sherlock get out of here.
John who had flung himself at Moriarty, who had joked with Sherlock minutes after being nearly blown up, who had nodded when Sherlock offered up both their lives.
Sherlock gets Moriarty. They are almost one and the same person. They would have been one and the same person had John not entered Sherlock's life.
John, the man who would always kill for Sherlock. John, the man who laughed at crime scenes, the man who asks like it's no big deal 'Are you wearing any pants?' and just shrugs it off when Sherlock replies 'No'. The man who, seconds after Sherlock admitted to experimenting on him (but that he'd be fine once he excreted it) 'I think I might have already taken care of that.' And Sherlock will never delete that.
People think they are boyfriends, but Sherlock and John know that will never happen. Sherlock, no matter how many times he thinks this over, has always come to the same conclusion; John completes him just as Sherlock completes John. They are brothers in everything but blood, and they will never be boyfriends. They merely complete each other, and you can complete another person without sex. But the Dull Humans never get that. Donovan and Anderson don't, at least. And the newspapers or the people who asked for an autograph never got that.
Sherlock has one folder in which he never deletes a thing.
And that is the folder of John H. Watson.