Fandom Tagging Question

[seekingferret]

Question I've been mulling all day:

I've been doing this writing exercise: http://seekingferret.dreamwidth.org/52973.html where I write Pale Fire-style footnotes for famous quotes from other books. If I were to put these on AO3, how the hell would I tag them? I think they're inarguably fannish, inarguably transformative, but it's not clear exactly what fandom they're in. Is it the fandom the footnote is about? Is it Pale Fire? Or is this origfic since it doesn't have the characters from Pale Fire and the actual characters it has are my invented OC specialists?