99.9% of the stories I write are Big Time Rush fanfics, just because I feel like it's my niche. It's the fandom I get the most enjoyment writing for, and when ideas come to me, they usually come in the form of BTR fic. I don't particularly feel restricted in the fandom, only because I can write about the actors or the characters, I can write about their backgrounds (which are never mentioned in the show), and there are dozens of minor characters and suddenly abandoned pairings that I can write about.
Plus, there aren't many people that write BTR smut (probably because the fandom is geared towards a younger audience), so I kinda feel like it's my duty to provide Mibba with quality BTR smut
I do a lot of crossovers with the fandom as well. I've done two Supernatural/BTR crossovers, a Resident Evil/BTR crossover, a The Hills/BTR crossover, and I'm currently working on a oneshot that's a Hunger Games/BTR crossover and a chaptered fic that's The Great Gatsby/BTR. I've done a couple Fight Club/BTR oneshots as well.
There's also a few actors I'll write about, more specifically Taylor Lautner and Chris Evans, and I have a few ideas that involve other fandoms. I have a few Twilight oneshots in the works, as well as a chaptered Hunger Games story, and I've dabbled in Supernatural for requests and whatnot, but I don't feel like my writing does justice to the show, so I generally feel more comfortable writing it if it's crossed with something I know better, like BTR or Resident Evil.