To me, there really isn't anything that is too AU because ya girl really loves an AU. But what I'm getting at with the question is, at what point is an AU not even a fic anymore and basically just an original work of fiction?
When I read a lot of RPFs, this is a question that popped into my head a lot. With a One Direction AU (one in which they're not in a band at all), the only things that mark it as a fanfiction rather than an original work of fiction are the characters' names and appearances. And there are those fics that change aspects of the celebrities' appearances, making it even more original.
So for those fics, you're basically reading an original work with the names of celebrities you like inserted in for the characters. Now, there's absolutely nothing wrong with that. Some of my old favorite fics were like that. But it does bring up the question of how AU can an AU be before it's not a fanfiction anymore?
These kinds of fics lend themselves well to being published after changing just a few key details with a ctrl+F. "After" by Anna Todd is one of these. For anyone who doesn't know, "After" started as a One Direction fanfic on Wattpad before the whole series was published as five novels with two spin-offs and a 2019 movie adaptation. It was a Harry Styles/OFC fic falling under the bad boy and college AU tropes. Now, "After" was popular after I stopped reading hetero 1D, so I haven't read it and can't tell you how similar the original fic is to the published novel, but I can't imagine too much would have had to be changed with the nature of the fic being so AU.
Even canon RPF fics are fairly AU in the first place since they are speculating about events that have no source material other than what has been witnessed and reported on IRL.
With non-RPF fics, the line that separates AU and canon fics is a lot clearer (even though I have a belief that unless a fic is a direct translation of a part of the source material, it can't be called canon, but that's a post for another time). In canon-compliant and canon-divergent fics, the author is using aspects of the source material that makes it obvious that it is a fanfiction. But with non-RPF AUs, the fic starts to resemble an original work the more AU it gets.
I feel like everyone in the fanfic community knows the "Fifty Shades of Grey" story, but if not, it started as a super AU "Twilight" fic and the series was published as insanely popular novels and turned into insanely popular movies.
Though I read the "Fifty Shades" books, I didn't read it when it was a fanfiction (not into "Twilight" fics, sorry), but as someone who knew it was originally a fanfic, I could definitely tell. I feel like there is a difference as to how fanfics and how novels are written (which I guess is another post I'm going to have to write sometime soon), and "Fifty Shades" read as a fanfiction front to back to me and aspects of it definitely reminded me of "Twilight," but for someone who doesn't read fanfics and didn't know the history of the story, it would just read as an original work of fiction.
A fic that is as AU as "Fifty Shades" isn't as reliant on the source material as one that is canon-compliant or canon-divergent, but rather it relies completely on the characters from the fandom to grab readers and keep them through the end as well as tell the story.
And while neither type of fic is easy to write, I do find myself having a simpler time writing when I have more source material to draw from rather than creating the world and the situations all myself.
I'm really not sure where I was going with this post, and there's not really a point to it other than to say, "Hey, some fanfics are basically just original novels with fandom character names!" Maybe my point is that these super AUs may be the future of publishing (I'm going to grad school for publishing, so I'll let you know soon). Maybe I just wanted to acknowledge the difference between the levels of canon-compliant and AU fics. Or maybe this is just me talking at you guys like usual.
What do you think? Are there types of fanfiction that you wouldn't consider actual fics or would call borderline-novels? Or do you think any work written within a fandom space is a fanfic, no matter how much it does or does not draw from the source material?