What fandoms are you writing for?

After reading some discussions on this forum here and there, and recommendations/links that were shared I started to wonder if it's possible that everyone writes for a different niche fandom...?
My list (to name a few truly important) includes HP, Arrow, Sherlock Holmes (classic), Lord of the Rings, Batman, mix of Marvel stuff (Iron Man, X-Men, Daredevil, Jessica Jones; and I've written a number of crossovers DC/Marvel because those universes are ideal for that IMO) and recently Supernatural.
Used to write to a lot of niche stuff as well (Polish criminal tv shows). Fandoms I don't think I'll ever write anything again are Alexandre Dumans (too exhausting to match that style, and needs a hell of research to get it right) and Pirates of the Caribbean (my first painful attempts to write in English; lost interest in the universe after they've killed off James Norrington).
The most niche one was probably a fic to Animals of Farthing Wood.
What about you? Are you faithful to fandoms or you switch them often? I discovered that I can't really skip between two very different fandoms (I pratically stopped to write to HP once I've discovered how many plotholes and blank spots there is to fill in Arrow).