Question

[cat_77]

Say someone writes a fic wherein it's sort of a fusion between Fandom A and Fandom B, but no characters from Fandom B are actually in the fic itself (basically, characters from Fandom A coexist in the same universe as Fandom B), does this get labeled as a crossover?

I think AO3 has a "fusion" option, but I also don't want to post something that shows up in searches for both fandoms and have someone click it hoping for characters from Fandom B where they simply are not there.