M'colleague Mathilda Gregory puts forwards a persuasive case for the defence here and it got me thinking. When an author like Sebastian Faulks writes a James Bond novel, or Michael Moorcock writes Doctor Who, is that not a form of fan-fiction? After all, I know that I would find it very hard to write 100,000 words of something if I was committed to it totally, meaning that, in the case of a shared world setting, I was a fan.
And to take my own case, is not the tie-in fiction that I write fan-fiction? The reason I ever tried to get a gig writing for Doctor Who is because I love the show, and always have done. The incredibly rich backgrounds of Warhammer and 40K constantly bring me back to writing for those settings too.
Admittedly, there is a lot of dire fan-fiction out there, in part because it's published having never passed the eyes of an editor. But if we ignore the dross, there are still a few gems out there (or so I'm told).
I was trying to work out what the difference is between fan-fic and tie-in fic (other than the fact that one's contracted and involves payment at the end) and considered whether it was all to do with characters. For Warhammer 40K I've created whole Black Templars crusader fleets and Imperial Fists squads, but my next Doctor Who story Terrible Lizards features the Doctor, Amy Pond and Rory Williams - all three Steven Moffat's creations. So it can't be that.
Perhaps it comes down to professionalism, the fact that there are so many editorial stages - including people responsible for the IP checking your work - but I am sure that many fans know the minutiae of Doctor Who history far better than I. So it probably isn't that either.
Maybe the conclusion we must conclude is, quite simply, that at the end of the day there is no difference between fan-fic and tie-in fiction, other than a possible perceived standard of quality, or lack thereof.
So, I throw this one open to the floor. What do you think?