I'm so glad you were 'misdirected' by the story, as was my intent. You're right, there's a waxing and waning of sanity, a pas des deux between Snape and Harry, that depends on them being at opposite ends of the spectrum. The castle and Binns were new characters for me, and the 'Alice' theme just seemed to make sense, as Snape definitely was stuck in a hole.
Thanks so much for reading, and I always appreciated your thoughtful comments.