Lawful Good: lurked for a month before posting to consume all fan content in their area of interest, internalise tagging conventions, and learn what content is already well-represented and what is lacking. fills in gaps in the fandom oeuvre out of a sense of community responsibility. alerts people who were like "why isn't there fic of this" that there is now fic of this and includes author's notes acknowledging those people by name for inspiring said fic.
Neutral Good: writes fic in response to prompts or community discussion. beloved by those who follow and interact with them. potential ouroboros relationship with fanon, where they both contribute to the development of fanon conventions and perpetuate them.
Chaotic Good: "I know no one asked for this but the idea wouldn't leave me alone so HERE, HAVE THIS THING THAT I POURED AN UNREASONABLE AMOUNT OF MY LIFEFORCE INTO. FREE ME FROM THE GRIP OF THIS FEVERED MUSE"
Lawful Neutral: scrupulously researched, impeccably canon-compliant fic. author may go out of their way to mimic the canon narrative style as closely as possible. readers' comments are likely to include "wow, this feels like it could have been an actual episode of [source media]!" high proportion of missing scenes, alternate POV scenes, and character interactions that should have been given screentime in canon but were tragically underutilised.
True Neutral: had an idea, wrote it, and posted it. may not be aware of the fandom zeitgeist or may simply not care. doing their own thing and feeling the fulfillment of an idea properly manifested. lower average hitcount than many other alignments due to lack of engagement with fandom or fanon and potential redundancy to already-existing fanwork. may be dabbling in a fandom they have no specific intention to revisit.
Chaotic Neutral: AUs, expies, self-inserts, reader-inserts, reader-directed/choose-your-own-adventure fic, crack, etc. We're all mad here! Mad and having so much fun.
Lawful Evil: "I have no justification and no excuse, but enjoy this exhaustively-tagged, morally unconscionable character torture! I sure did :)"
Neutral Evil: fic would not have existed if not for the motivating power of spite and frustration with the fandom (or, in certain end-of-the-bellcurve cases, the source media, but in general spite/frustration toward the source media is common in any alignment). whatever other motivations there may be, the fic is an express Take That of greater or lesser subtlety. this author is so mad. why is everyone doing this wrong? WHY MUST THEY BE THE ONE TO RIGHT THIS WRONG? THEY'LL SHOW YOU WHAT THIS CONTENT SHOULD BE. THEY'LL SHOW YOU ALL!!!
Chaotic Evil: wants someone to suffer. is it the cause of their spite, whom they are using Take That fic to call out? is it their readers, whom they are trolling, whether with badfic or with a poisoned-apple plot that seems to be all the reader desires before it takes a horrible twist? is it the creator(s) of the source media? it doesn't matter, as long as someone experiences regret as a result of the fic's existence.