Prompt Challenge: Disappointment

Write a 500 word drabble, using this opening scene

Harry sat in the chair in front of Dumbledore's desk, looking forlornly at the floor. He didn't dare look up for fear of seeing the disappointment in the Headmaster's eyes. What had he been thinking? Finally, after what seemed like ages, the headmaster spoke, "Harry, look at me please." Harry reluctantly raised his head, headmaster and pupil looked at each other for a few moments, then Dumbledore sighed and spoke once more, "Harry, I'm very disappointed in you."

The rest can be what ever you want. What did Harry do to get into so much trouble? Were Ron and Hermione involved? Can take place during any year, up to 6th.