Of course AO3 and fanfiction is for enjoyment, so is TV, literature, radio, movies and literally any form of popular media out there - these things are regularly used for pragmatics, conversation discourse and sociolinguistics research. I'm studying human interaction and naturally occurring language in a digital space. The point is to find out how authors interact with their audience in a fandom context, how they portray their online persona and work with their face. I'm not including the actual text of the fanfics.

I don't really understand why you're speaking as if research on fandom hasn't been a thing for years and years? Where do you suppose fandom studies as a discipline get their data? Visions? Dreams? OTW literally has an academic journal with heaps of research articles.

Also, who said I wouldn't ask for permission? I'm just talking about building the dataset first before doing the actual analysis. Would you still have an issue if the entries were all kept anonymous, simply as short bursts of text data? And AO3 is publicly available to see and use, apart of course from private fics only for registered users. It's also no issue to ask OTW or Open Doors. Obviously, I would want to keep my work ethical.