And yes, someone may have noticed that I've now posted a similar prompt in the X-Men kinkmemes. Hush, you.
The Theory of Narrative Causality
By: anonymous (if the author's de-anoned, let me know? Because Jesus.)
Fandom: BBC!Sherlock Holmes
Pairing: Holmes/Watson (with fic!Holmes/fic!Watson, LOL INCEPTION)
Rating: Probably NC-17
Prompt: Sherlock is a well-known fanartist whose online antics always land him on fandom_wank. John's a beloved BNF fanfiction author. They meet at a convention; geeky love ensues. [NOTE: The actual story differs from this slightly, but still works.]
Warning: It's a (loooong) commentfic, so navigating it can get rather irritating. Hopefully someone somewhere has posted a link to the author's journal.
(I now have no excuse not to go to a cafe that doesn't have Internet so I can actually get some work done. Yes, Internet, this is what you've reduced me to.)
ETA: I keep thinking about how strange it would be to read fic of characters with your own name and your lover's. I share a relatively rare first name with a minor but infamous character in Harry Potter, and it still trips me out whenever I see it.
ETA2: Link to the Fandom Lounge post of this, which itself links to the fic's main parts. I think I was so excited after reading that I entirely forgot that this was where I'd found it. Thank you, chofi . I'd lose my head and just keep smiling half the time without you.
ETA3: Thanks, dracontia . :D It seems the author of this is falling_voices , and here's a round-up post of everything for it.