It had been like that since fifth year. Y/n, walking through the Slytherin common room, and some sixth-year had reached out to touch her hair. Smiled at her like she was something to be won. Billy had crossed the room before the smile finished forming. He hadn't used his wand. Hadn't raised his voice. Just broke the boy's wrist, quick and clean, and told him that if he ever looked at Y/n again, he wouldn't get to keep his eyes.

That was the thing about Billy Robinson. To everyone else, he was handsome, charismatic, untouchable—the golden boy of Slytherin, the Quidditch star, the boy every girl wanted and every bloke wanted to be. But to Y/n, he was something else. He was the boy who remembered the exact day she'd first mentioned her favourite flowers. Who left little gifts outside her dorm door for no reason at all. Who called her princess like it was the only word that fit. Who looked at her the way other people looked at winning the Quidditch Cup—like she was the only thing worth fighting for.

Everyone knew Billy Robinson was dangerous. But Y/n was the only one who knew he was dangerous for her.

It was a Saturday. No classes. The castle was quiet, students scattered across the grounds and common rooms. Y/n walked the corridor with Astoria and Pansy, their footsteps echoing off the stone walls as they left the Slytherin common room behind. The library was the destination—a Potions test to study for. Astoria was mid-sentence, chattering about something that had happened in the common room that morning, her hands moving as fast as her words.

Then a hand shot out from a doorway.