Wow! My goodness, you really NAILED Filch's voice here. I could practically HEAR him in my head, this was SO VERY him. And Umbridge... *shudders* Not that I can fault her taste, but yuck. The castle really does take care of her own. And I love the small flashes of magic Filch had, it makes sense that even a Squib would get those since the occasional Muggle has flashes of intuition. ;) You made Snape/Minerva totally plausible! And the end was perfect. Really well done!