I started out with Warhammer 40k writing backgrounds for my armies, but I was young so they were dreadful (although there was one I did for Nano one year that I'm still kind of fond of, a first-person life story of a Sister of Battle).
A few years after losing interest in 40k I kind of stumbled sideways into Buffy the Vampire Slayer fanfic (prompted by Amber Benson singing Touch-a Touch Me at a Rocky Horror event, I ended up throwing together a whole Sunnydale Rocky Horror thing - funnily enough, Tara wound up not doing that song; also, lyrics are difficult, mine were not good), then - I forget why - after posting that to a Willow/Tara Yahoo fanfic group, and reading several others, I suddenly though '...so what if Tara's a nightclub singer in 1930s New York, and Willow is The Shadow?' I'd followed (but never wrote) Xena fanfic prior to that which gave me the notion of Uberfic as a defined 'genre', and since I'd really never found canon Sunnydale a very interesting setting to begin with, and just wanted more Tara, that was a good fit. So the next few years were a series of 'Here's a movie or tv series or video game I like, but wouldn't it be better with Tara in it? Yes it would, and here's how it would go...' I also got involved with a collaborative project to make a sequel series to Buffy, called 'Watchers' - initially to help with photoshopped images for the episodes/stories, but I ended up dipping into writing as well during the two years I was doing that. (Unfortunately, at the time I had an ageing CRT monitor, so looking back on what I thought were pretty decent images at the time,
man did I get the contrast levels wrong between elements because my screen was dark and I couldn't tell the difference.)
I flatter myself that my writing got better as I went along (I mean, it
had to be better than the 40k days) so I don't mind sharing that I made a website for Willow/Tara uberfics - mine and others - and it's still
here. I took a few years off due to real life derailing a lot of things, but last year got back to the 'Tara is She-Ra' series,
like so (that's where my avatar comes from), and since then I've been writing various short stories whenever the mood takes me, or there's a holiday (ghost story for Halloween, Tara cosplays as Samara for N7 Day, that kind of thing; gotta think of something for Christmas). The Willow/Tara scene is understandably quiet these days, but back in the day I spent most of the time I wasn't writing keeping up with all the other uberfics doing the rounds.
Speaking of N7, during my 'hiatus' I did spend a couple of years doing forum roleplay in the Mass Effect setting (Cerberus Daily News, if you're curious), which I suppose is basically collaborative Original Character fanfic. That encouraged a trend I'd developed during some of my longer Willow/Tara fics (primarily 'Hellebore') of exploring all sorts of random details of the setting just for their own sake; ended up making up so much extra background for my character I made a
wiki just to keep it all handy for reference. I still add to it now and then, even though I'm done roleplaying - just throwing in random mostly-asari-related ideas for fun's sake. I've never read much Mass Effect fanfic though, of any sort - if we're being honest, I'm not that interested in stories about the game's characters (I mean, I
know their story, I 'wrote' it when I played it), and so far as CDN went I had this notion that reading other people's threads about what their characters were up to with each other in private would constitute OOC knowledge, so I tended not to read them on the basis that Daia (my asari) wouldn't know about those events.