I think I first learned fanfiction was a thing in middle school, thanks to the Creatures computer games. That would be about 1998, give or take. That was also about the time I was learning the Internet was a thing, and spent my some of my free time hanging out in MSN chat rooms and stuff. (Hey guys, who else remembers a/s/l queries being commonplace and not automatically creepy and stalkerish?)
Somehow, I made my way to a Creatures fan forum and found that people had written stories based on the games. It kind of blew my mind. I don't remember any specific thoughts, but I used up a lot of paper printing off a particularly good series of long-ish fics—and I still have them! I was already something of a writer (so my parents and teachers told me!), so fanfic seemed like an awesome way for me to get involved in the community. I started writing my own fic pretty damn quick, but I never finished it. Middle school was not a great time for me writing-wise, at least not until the 8th grade, when I actually had a competent English teacher.
1999-2000, my freshmen year in high school, was when I got into Farscape, though, and that changed everything. I got involved with a little Pilot fansite called FaDoP (Friends and Defenders of Pilot), and they were the most amazing group of people I'd ever met online. Fanfic was definitely in, and I wrote up a decent-length fic—about 20 pages, single-spaced with indented paragraphs, definitely the longest thing I'd ever written at the time. And that one I actually finished, with an alternative ending and a sequel, even.
And that's how I learned about Mary Sues. ^_^
The FaDoPer who pointed out that my OC might be a Sue did so in pretty much the nicest way possible. I think they were going by the then-standard "idealized version of the author/person the author wishes they could be" definition, to which I agreed that, yep, that sounded about right! I was a bit defensive about it, as I recall, so my agreement was sort of a passive-aggressive attempt to own whatever so-called "flaws" people were finding with my work which was obviously perfect, thereby transmuting them into deliberate style choices that I totally did on purpose for a reason so don't judge me... but still, at least I didn't throw a tantrum or anything.
Anyway, I think I found out about fanfiction.net from my fellow writing-inclined FaDoPers, and that Farscape fic is the first thing I posted there. Apparently this was in early 2002, which I'm pretty sure is a good bit after I actually wrote it, but that's beside the point.
By then I was heavily involved in role-playing, mostly on Neopets, and I wrote a handful of fics inspired by or directly based on what I was getting up to in RPs. In particular, I started writing a massive Harry Potter epic... that I never finished. I think I discovered OFUM not very long after discovering ff.net, and through OFUM I found the PPC, so I'd heard of "canon," and I wanted my story to harmonize the events of the RP with the books as much as possible, so when new books came out and changed everything, it was difficult to recover my momentum.
Plus, by 2004 I was pretty entrenched on the Board, and PPC stuff took over a good bit of my free time. I remember starting and never finishing a fair few fics between 2003 and 2006-ish, but since I'm pretty sure they were all garbage, that doesn't bother me. I did write another Farscape fic in 2005, after the miniseries came out, and I've poked at the Epic Potter RP Fic, but basically my interest in writing my own fanfic petered out in favor of writing PPC stuff. It's a lot more fun writing for an audience who knows you, likes you, and is generally willing to give meaningful feedback. And here we are!
~Neshomeh, who wrote a lot in this post, jeez.