I read this fic many months ago and cannot find it again anywhere :( It was Brittana, and I'm almost positive it was categorized as magical realism. Brittany and Santana had met in many previous lives and Brittany could remember all of them but Santana couldn't. It showed maybe a few different times, including when they were young and Brittany introduced herself to Santana on the playground. Sometimes she would have nightmares, I think, where she would see things happening in other realities or universes. It ended with Santana introducing herself to Brittany in the playground instead of the other way around, and you got the idea that things would work out this time.
Any help? It was relatively short, a one-shot I believe and very very good.
I have my fingers crossed!