Request #477 From Philippa

 I’m looking for a YA novel where the main characters are Connie and Rudi, and one day they wake up in each other’s bodies. Connie is a normal teen and Rudi is a prince of some kind. Slowly they work out that something is out to get them and during the final showdown bit they switch minds frequently; one of them is climbing a wall; it’s nighttime. I remember the book cover art: light blue background, with one face front on and one face in profile, overlapping in an optical illusion