I’d prefer it if you chose minor characters, since just saying a major villain is Slytherin and the hero is Gryffindor is pointless, as that is often the case. Besides, Slytherin does not mean that they’re evil. Also, just taking a character from Divergent (or other books) where they’re already sorted into similar categories, is a little bit pointless, unless you don’t think they’d be in the corresponding category.

You don’t even have to do Hogwarts houses. Ilvermorny, Beauxbatons or Durmstrang would be fine. And if you want to go the other way, and sort Harry Potter characters into factions or similar, you can, as long as you give a reason.