I can never resist a good cross-over, and this didn't disappoint. Oh, my aching sides! I lost it completely with your description of the tower and its new beard. Oh, and the Muggle Trigger, that was genius! Only two tiny nits: I'm not sure Filch would call Arabella "Bella" simply because of Bellatrix Lestrange, also called Bella. Also, I'm not 100 percent sure on this one, but I don't think any part of the castle goes beyond seven floors, so the tower would only go to seven. Unless this was an especial, enchanted tower, I could buy that :) But those are minor. I really, really enjoyed this.
Poking around on ashwinder and ran across this story. It's extremely original. The image of Filch holding on to the furniture to keep from going out the window is hysterical! This is a really cute story.