Misunderstandings & Travel Fic Recs

I'm looking for fics with misunderstandings or mistaken Identity/Identity fraud, where time travel or dimension travel (or fandom crossover) is involved.

I've looked through tags in ao3 and know for fact I'm missing out on some good fics but for some reason can't find any. I'm aware sometimes authors don't tag properly so that's also part of it.

I'm open to fics from other sites too.