An interesting little story, very different. It could use more polish - you separated the end there, but I'm really not sure why - but I think you did a good job with this. It was refreshing.
150 points is really quite a lot, though. Maybe try a smaller number, like eighty or so.
Author's Response: I wrote this story over a year ago and I'm glad you like it. The reason I separated the end was that at the time I was exploring actually writing Professor McGonagall's confrontation of Severus Snape. After several false starts I gave up: I was never satisfied with the results and thought the story still had merit without that scene. Thanks for your review.