Not a secret anymore

Sheldon thought of what he just heard, he had never heard of a similar case in his life. It explained, of course, why his muggle repellent hadn't worked, and why she was always able to sneak into his room. Shenny. HP's universe with a little mixture of "The magicians". Also at AO3 with it's past title "A huge secret to keep". EDIT: Reuploaded: no more hyphens NEW cover image (mine)