Lyra Heartstrings tries her hoof at writing fanfiction. She succeeds beyond her wildest expectations.
A sort-of-crossover with Watership Down (the novel, rather than its animated adaptations), which you probably need to be reasonably familiar with before this makes much sense.
(Originally intended to be a synopsis for a much longer fic when I wrote it back in November 2017, but nothing ever came of that, and I've since come to think the laconic style here actually works better for the idea.)