I got introduced to the online fandom community through searching fansites, forums, and message boards way back in the day. It was 1999/2000 when I first started reading fanfiction on fanfiction.net, and privately writing my own in my own time. The first slash fic I ever read was Jake/Marco from Animorphs.
In 2003 I joined LiveJournal, which was the first online platform I ever actively joined since before I was just merely lurking about. At this point you still needed to get an invite code to join LJ before they discontinued it later in the year. The fandoms I was in at this time were Buffy the Vampire Slayer and Harry Potter. My username is a combination of two my favorite characters from two different fandoms, Faith Lehane (BTVS) and Max Guevara (Dark Angel). My introduction to the fandom community that resided here on LJ was perhaps the most influential part of my online experience, from the specific fandom communities where you could participate in discussions to befriending like-minded individuals who shared the same fan enthusiasm as you did. Yes, fandom wasn't always a picnic as there was plenty of drama and controversies that occurred for one reason or another, as that's part of the fandom experience in general no matter where you are, but overall it was still a good experience nonetheless and I liked how lively this place was with fandom activity and how there was always something for everyone, regardless of what fandom you were in.
My fandom history on LJ is more or less just me being an enthusiastic fan about the things I liked. I wrote episodic reviews weekly for the shows I was watching, participated in discussions in communities or on other people's journals, I wrote metas and even did some fanmixes/ficmixes every now and then. I really stretched my writing muscles with doing metas and things like that during fandoms like Heroes, Veronica Mars, and Battlestar Galactica, and while I was in the Supernatural fandom for a brief period of time it was also the fandom that got me to go to my first ever fan convention, which would contribute to my love of going to conventions such as Dragon*Con and other smaller local based ones.
Throughout this, however, I also witnessed firsthand the unfortunate downward spiral of the fandom community on LJ. The Strikethrough of 07 was definitely the biggest blow fandom took on this site and it shook everyone up, and people tried to find different platforms to migrate to.
In 2011 I joined Tumblr, and in 2012 I created a backup DreamWidth account that I haven't done anything with aside from friending people there who bounced permanently from LJ just to continue keeping tabs on them. Otherwise, I mostly just still use LJ and Tumblr for my fandom outlets, for different reasons of course. Tumblr is where most of fandom resides nowadays (aside from Twitter, which I don't have) and it's where I can reblog things that are relevant to my fannish interests, and LJ, even if less fandomy that how it used to be, is where I can still express my thoughts and opinions about the things I am currently consuming in media since I don't feel comfortable doing so on such places like Tumblr where performative wokeness also sadly resides.
I am still very much into fandom. I might not be as much of a participant as I used to be, but I am still within the community. I just can't not ever stop being in fandom because it is my form of escapism. No matter whether online or in real life, no matter what platform fandom migrates to next, I will always be a fangirl and love fangirling about things and sharing this love with other people who are just as fannish as I am.