an Eighth Year at Hogwarts

Everything is different. Because of the Great War, and how many died in it, barely any students came back to complete their eighth (make-up) year at Hogwarts. That caused some... changes. Such as: instead of the Eighth Years separated into the four houses, they're all combined into one. Meaning, there are changes in who the room mates are- and that might be a change for the worse.