So, falling under the heading of no surprise whatsoever, I've been reading a metric ton of Frozen fanfic, more specifically Elsanna. While I do love fanfic, Sturgeon's Law applies, plus I have my own pecadillos, starting with the simple fact that, given who and what the characters are, I'm not going to read anything IU ("In-Universe").
A lot of the short stories (those of 2000 words or less) are simply pointless; the writers don't know how to pack in the details the way a short story demands. That said, I readily deleted "Cacophony," "Empty Halls," "Something Crazy," and "Closeted" as unreadable. "The Takeover," like "Sorority Sisters," is simply too fast and ridiculous to be believable; the characters fall into trust (much less love) simply because they have to for the sake of the plot, and never question their reaction to one another, so I never finished them.
That said, there are some worth mentioning, not because they're good romances, but because they're among the most compelling illustrations of mental illness I've seen yet. You Are and Elsa is Suffering both show the progression I've noted before; a few chapters of crud, followed by the author hitting his or her stride, followed by a tragically compelling mess of a story. Those two are like having a crazy lover you can't stop seeing; for all the drama and emotional toil, the high points are just amazing.
If you want the best Elsanna story (and you probably don't), Anna Summers, Personal Assistant is probably your best bet. In what has to be the most giggle-inducing scene ever written, Anna discusses safer sex and the author absolutely nails her voice. Hilarity ensues.
Fanfic is a supergenre, and the AU settings necessitated by my restrictive choices enforce all sorts of genre categories that drift far from the original material. (I have yet to see an SFnal Elsanna story. I may have to change that myself.) But if you like to read, fanfic is a way to keep those characters moving forward when no one else will give you more of what you want.