OH wow i love these types of questions it really makes me think hard abt them. i'd say it's a variety of things amalgamated into each other. i've been writing for a long time, fic or otherwise, and so i have a big archive of just... words and phrases that i put tgt over the years that i never released to the public. sometimes certain parts of my stories will come from those, and if the phrase is particularly good i might even edit it and tweak it to fit into the fic :> basically a lot of different art that i consume inspires my fics. sometimes i read the blurb of books and then write what i think wld happen if my fandom characters were put in a potential situation like that (without reading the actual book itself, to make sure i'm not relying on someone else's thoughts).
poetry and songs are also pretty big sources of inspiration. it doesn't even have to be lyrics, just the song itself can evoke something in my imagination. like recently i've been thinking of sleeping at last's saturn with its not-haunting yet void-like feeling and florence and the machine's free when she sings "to exist in the face of suffering and death and somehow still keep singing" i think it ties well w a fic ive been spinning in my head for months now <33
ofc fanart too is super amazing for this too !! there's a fic i've been working on slowly which was inspired off a fanart i saw on weibo and i CANNOT find it URGH i wish i cld track it down. but yes. consume widely and push your comfort zones. actually it's not just about consuming widely, it's about consuming intentionally. thinking about more than just "what does this make me feel" to "why did the artist choose to make it like this" has sparked more inspiration in me than you'd expect !!