I just really like Sokka/Suki, and after sneaking a little bit into "Earth Girls Are Easy", I had to do their own. I kind of love them.
Spawn fic written around fanart. It does not get nerdier.
Within the "Two Birds" continuity, bridging the gap to spawn fic. This actually started it, because I wanted some kind of conflict between Mai and Ursa, but I also love Mai/Zuko and court stuff, so...
Kind of riffing with a friend about what would happen next in the Two Birds continuity. This happened.
I needed to stuff the missing Toph/Zuko fieldtrip into the story, and add the fate of Zuko's mother. Fits in during the Sozin's Comet episodes.