This! This story is so utterly believable, truly. I love the no-nonsense way in which Miss Glomp treats class matters--and the no-nonsense way she treats the relationships among the women of Hogwarts (2D and 3D alike!).
Your attention to detail in this--how even Portraits feel the chill, the specter of portrait-rot, the ways in which Arethusa and her cohort manage to eat, drink, and be merry (for tomorrow they're still paint)--you create a truly rich world with characters that don't just disappear for being offscreen (or out-of-viewing, I suppose).
The Coven Fortnightly is a crucial support system, and I'm tickled to read about the relationships among those who attend. And Arethusa's rationalization that she and Vi ought to be counted members of it--but good grace not to insist--is lovely.
As is everything. I particularly love how Arathusa finds "butch" to be vulgar, but "hitch" to be less so (it does seem like the sort of word that's ripe for reclamation!).