I think that having it so that anyone referring to objects as “you” creates an opportunity for demonic possession is such clever world building. It just instantly necessitates a layer of intricacy that the author fully rises to the occasion to create, from every magicians’ clock ever being possessed, to them knowing the copier is going to wind up possessed because people can’t help but curse it out on the regular, to keeping the pens in salt, this world is just fun and so well described.

Also, as a teacher, the writing is authentic.