What if Hermione was poor and Ron was well off? What if Harry had a good family but Ron was homeless? What if Dumbledore was strict (and still nice) but Snape sometimes bent the rules for Harry or other students? Your goal is to write a story where one or more facts of the Harry Potter universe are flip-flopped and it impacts the story in a big way.
Other ideas (but feel free to ignore and come up with your own):
- Harry's parents survived but Draco's didn't.
- Hermione is a full blooded wizard and Ron is half or Muggleborn.
- Remus is Harry's Godfather who has been on the run because of his werewolf status, and Sirius has been teaching Defense at the school (lots of good opportunity for drama between him and Snape there).
- Ron is rather popular for some reason and very confident (maybe his dad is the minister or something) and Harry is more of like the side-kick.
- Draco is in Gryffindor and someone else typically in Gryffindor (Hermione maybe?) is in Slytherin. How their personalities are the same as before or different and what friendships exist or don't exist could be interesting.
- Snape is the Gryffindor head of house and McGonagall is the Slytherin head of house.
- McGonagall is the Headmistress and Dumbledore is the Transfiguration teacher and Gryffindor Head of House and deputy-Headmaster.
- Fred and George are studious and Percy is a prankster (possibly in an annoying yet not-funny way?).
The goal is NOT to switch two character's entire personalities and life stories with each other and just switch their names. Instead just change one or two facts with other characters and see how that impacts their personality and the story based on who we already know the characters to be. For instance, if Dumbledore were a strict Headmaster, yet still a nice person like he is in the stories, and Snape were sometimes lenient with Harry or other students and didn't always tell the Headmaster that he'd bent rules for students, yet he still had his regular Snape personality, then there must be a reason for it, right? There would be an interesting story there to flesh out to help the readers understand why this is the way it is.
I wouldn't really like to see a story in which Harry somehow ends up flung into an alternate reality. I'd like to see a story where this has just always been the way of things.