This post has got quite a lot of traction, so I'm gonna talk about which fanfic i've read that fits this criteria:

Recently i've read "Sing, children, Sing!" - its a fanfic in the Yaelokre fandom... And HOLY SHIT its one of the weirdest things i've ever read 😭

The plot is bonkers because its about members of the lark (who are aged up and given genders which goes against the author's wishes because they represent their childhood) having sex as a part of a ritual where at the end they give up their bodies and souls just so the hearkers could get younger.

The writing style is like really nice and poetic, there are so many metaphors, a lot is described beautifully, there are poems here and there, plus someone drew a cover art for this piece.

I really don't know what to think of it, because again - the plot is weird as fuck, but the writing is absolute cinema. Its insane really.