AU where Sherlock and John haven’t met but live in parallel worlds but can see and talk to each other in mirrors or reflections.

valeria2067:

—All of this starts in early childhood for both of them. 

—John’s home life is already unstable, thanks to his father’s drinking, so he knows even then to hide it, not just from his parents, but from Harry, too.  

—Mycroft scolds young Sherlock for being so “boring” and “typical” as to invent imaginary friends, but the mocking hides a real concern that perhaps Sherlock is mad, or…. even more frightening… that perhaps Sherlock is not.

—John manages to get a seat near the window in his most difficult science classes. It’s not so he can stare out at the sky; it’s because Sherlock can explain most things to him better than any teacher or professor.

—Sherlock takes to carrying a small, foldable magnifying glass and using it in anything and everything during investigations. He doesn’t actually need it. What he needs is to see and hear John smiling and saying “fantastic!” when the others around him are calling him a freak.

—John enlisting and going to Afghanistan nearly ends their relationship. Sherlock doesn’t want to see John die, and he fears (nearly as much, if he is honest) that there will be less time for them, fewer opportunities, no privacy.  It is only dumb luck that one window of a nearby parked jeep is clean and smooth enough for John to catch a glimpse of Sherlock’s frantic warning – otherwise, the bullet would have pierced John’s heart, not just his shoulder.

—Every time Sherlock hears someone complain about “folk these days doing nothing but staring into their phones,” Sherlock smiles to himself. It is the greatest social shift in history, as far as he is concerned. John is with him almost constantly, now, staring at a somewhat less expensive phone somewhere in another universe.

—They may say they keep the brightness low on their smartphone screens because of privacy issues or battery conservation, but Sherlock and John both know that’s not quite true. Sherlock also says that the sleek, shiny phone is more than a tool for his work; it IS his work.

And as anyone can tell you, Sherlock Holmes is married to his work.