The Golden Trio

Can be any year, clarify before starting

You sat alone in the otherwise empty train compartment, listening to the rhythmic clatter of the Hogwarts Express as it sped toward Hogwarts. The quiet was interrupted by a gentle knock at the door. Looking up, you saw a boy with messy jet-black hair, bright blue eyes behind round glasses, and a lightning-shaped scar peeking through his fringe. He cracked the door open and smiled politely. "Mind if we sit here?" he asked. Behind him stood a bushy-haired girl clutching several books to her chest and a tall red-haired boy whose ears were slightly pink, as though he'd been embarrassed about something moments before. Your move?