The dynamic between Fluttershy and Discord has always been one of the more fascinating corners of 'My Little Pony' fanfiction. A lot of writers latch onto their canon friendship and push it into far deeper, more philosophical territory. There's this one ongoing story, 'Chrysalis Effect', where Fluttershy helps Discord navigate something like remorse after the events of the show, treating his chaotic nature as a trauma response rather than just a personality trait. It gets surprisingly dark, but in a way that feels earned for both characters.
Other fics go the opposite direction and lean into pure, wholesome fluff. I've seen dozens where Discord tries to understand pony concepts like 'tea parties' or 'animal care' and utterly fails in the most endearing ways, with Fluttershy patiently guiding him. The ship tag for them exists, obviously, but I find the platonic explorations often have more interesting things to say about the nature of kindness itself. Sometimes kindness confronting chaos creates better stories than romance does.
If you're looking, the 'Fluttercord' tag on AO3 is your main hub, but you have to filter carefully to find the friendship-centric ones. I usually sort by 'Fluttershy & Discord' rather than 'Fluttershy/Discord' to avoid the romantic plots, though some authors tag both.