
imo it depends on how similar they are. Like I took inspiration from a fic but it was just the hook of the story, which wasn’t an entirely original idea from that specific author. I still put them as inspiration but i didn’t bother asking first. But if you wrote something that is more uniquely tied to that specific fic then I would. Especially if it’s a fanfic of their fanfic. Regardless, if you’re unsure then just message them. Can’t hurt.