This is an utterly brilliant and original story. I must admit that many good things come in small packages and this story is a very good thing!
Two minor criticisms, the appearance of Luna into the picture was very sudden; perhaps beginning to introduce her at the beginning - if only a few lines or mention in Harry's musings - would have made the story slightly stronger, but nevertheless it still works.
Secondly, I think a possible epilogue is needed just to tie things up nicely, but again it is still OK as it stands.
Tibi grates ago fabellae, ave atque vale, Clivius.
Author's response
I considered doing an epilogue, or longer denoument, but decided against it for one reason: I wasn't able to come up with ideas for it that weren't already done to death. ;-) Thanks for your review.