One Man's Scare is Another Man's Normalcy

[HG/SS] Halloween is coming to Hogwarts, and George has prepped the perfect tricks for the holiday for all the students. When the tricks seem to have gone pear-shaped, the mystery of a series of strange transformations seems to fall in George's lap. But was it really George? If so, why? If not, then who did? AU, EWE, Post-War, Complete and Utter Crack [COMPLETE]