Is there a series you love but can’t bring yourself to write/read fic for?
Mine is Avatar the Last Airbender
As much as I love the original show, I don't think I could write a fic for it. It's too perfect as is and they managed to wrap things up pretty well (ignoring the comics) in the finale. I don't think I could add anything to it, not even as a crossover, an AU, or as a continuation fic. It's one of those things that's too sacred to touch, much like the Original Star Wars trilogy and Lord of the Rings. Anything I would write would pale in comparison to canon. It would be like trying to write fanfic for The Godfather or War and Peace.
That and despite this show being American in origin, the world presented in it is rooted in East Asian culture thus creating a sort of cultural barrier for a westerner like me to fully grasp and authentically present.
With the exception of LoK and Voltron (the former is too divisive and the later became a dumpster fire), I however will write and come up with fics for its spiritual successor shows, 2018 She-Ra and Dragon Prince. And while I think those are solid shows, I don't consider them on par ATLA which ins nearly flawless in execution whilst POP and DP have some flaws but are still pretty good shows with some room for improvement in some areas.