This was a story I read on Fanfiction.net around 13 years ago, though I believe the story had been around for a few years before that. The key part of this story is that the writing style was perfectly imitating King's writing style and prose mannerisms, to the point I was half-sure that King wrote it himself and posted it on various fansites for whatever reason. Indeed, some fansite I found well after my initial reading mentioned the piece and also guessed that King wrote it himself (the same site mentioned the story being posted on various other websites other than ff.net, but I couldn't tell you what they were).
Every darn thing I remember of the plot:
The story is written from the point of view of Stephen King himself, in the 'real world.'
After a stop on a book tour, King decides to find a bar or restaurant to eat dinner in. He finds a bar named after a bar in one of his novels. King finds this interesting, as his editor has previously gifted him with a list of every business in America named after one of his novels or an aspect therein (including one sex shop called Gerald's Game) but this bar was not on the list.
Not long after entering the bar, he enters the restroom, and when he comes out, the bar has changed. Most importantly, he finds he recognizes the people surrounding him. That's the girl from Firestarter and her father at that table. That's Carrie White and her date, still in prom wear, at that one. And that obsessive fan suddenly needing his attention is none other than Annie Wilkes!
King attempts to flee, but is threatened outside by Christine on one side and some other character on the other, and re-enters the bar.
While I don't remember the actions that take him there, eventually, King gets shunted into some other dimension outside normal space, and is talked to by a pair of creatures who have a role similar to supervisors of the universe.
The supervisors need to talk to King because they preside over an infinite universe--one in which everything happens eventually. In a truly infinite universe, there's no such thing as fiction.
Except for the fact that, before King invented the pen name, Richard Bachman didn't exist. In an infinite universe, Stephen King made something up! This threatens to unbalance the whole of reality, and King ends up confronting Bachman with creation at stake. I don't remember where the conversation goes, but eventually King returns to the real world.
Does anyone else remember this story?