Just finished the book and found it enjoyable. However there is one thing that I can’t quite figure out and that’s who was the one-eyed rook.

At the end it sounds like the rook is reunited with the skull of a little boy before the Pale Lady takes its life. Was the rook symbolic of a famous fairy tale or a character from the 1st book? It’s been a while since I read the “The Book of Lost Things” so I can’t recall anything about a rook or 1-eyed person.