Erin always tended to hang around after Quidditch practice, making sure all the equipment was put up, watching the locker room empty - often, continuing to fly until the sky turned dark. So when practice ended today and he didn't immediately go to shuck off his leathers and green Quidditch robe, it wasn't too unusual.
Trundling back from the locker room with a black box tucked under his arm was slightly less usual, as was claiming a bench on the sidelines instead of taking to the sky. His team was in various states of departure, some already gone, some hanging around to chat in small groups of twos and threes, but otherwise there was no one on the pitch and it made a good backdrop to his serious deliberation. Everything Erin did well, he did on this field. Therefore, it stood to reason he'd do his best brainstorming here.
Erin'd put a lot of thought into the Tournament lately, and into unlocking his "prize." This box had cost him an acromantula sting to the leg, which even by the resident brawler's standards was moderately painful. He'd been too angry and embarrassed about his low score for days after the First Task to even touch it, instead shoving the simple wooden box under his bed after a brief preliminary investigation failed to unlock its secrets. The box didn't deserve the way he'd treated it, angry kicks and silent treatment for every taunt he'd gotten about his losing strategy. Punching his way through the maze hadn't worked too great for his scores, and it didn't make the box pop open either. But he couldn't ignore it anymore. Things had changed.
Specifically, an ickle bony batlike horse had appeared over the lock, which Erin took as a clue. He knew what it was, though he'd never seen a thestral himself - it wasn't like there were that many nightmare horses around. So he sat now and he stared at it, and he thought about thestrals. Death. Invisibility. Meat.
Maybe he should rub some steak on the lock and see what happened.