"It locked when you came in," Branwen reported mildly, while Vicky struggled to open the door. "Perhaps that's why everyone avoids this room."
She frowned when Alohomora didn't work, though. A puzzle. And while she enjoyed puzzles, she wasn't generally in favour of ones where she was locked in a room to solve them.
Then she sighed. "I think we're well and truly stuck. We might as well make the most of it, while we figure out how to get out. As it is, I don't know who you are. Gryffindor, 6th year, certainly, but no name comes to mind. I'm Branwen Dunstan. Ravenclaw, 6th year."