my understanding of the (recent) fanfiction timeline as i see it :
2000 - 2011: livejournal and fanfiction.net, plus loads of small scale sites/forums. writing style can best be described as "sincere". a lot of stories are relatively serious in tone as well as content. some tropes are present. i mainly remember a lot of independent worldbuilding - authors creating their own oc villains, for example.
2012 - 2016: ao3 rising. tropes develop further and crystallize more firmly. userbase is a lot of teenagers. more crack. a lot of internalized homophobia/working through gay feelings plots, likely due to popularity of major fandoms like sherlock and supernatural. big mix of very good as well as very silly writing.
2016 - 2019: ao3 still growing. further crystallization of tropes and AUs - coffee shop, high school, florist, sharing a bed, etc.
2019 - present day: romantasy takes off as an irl genre, books literally developed directly from fic storylines. tropes are everywhere and used as shorthand to describe media. annoying. ao3 fics now getting worse - too many tropes, too frequently. too many fics based entirely around specific tropes. feels like some kind of ouroburos thing that we can't get rid of. new issue: male characters are written worse. genuinely not sure what's causing this - possible consequence of genderslop wars, or men and women not spending as much time together irl
