His Dark Materials Trilogy by Phillip Pullman
This Pullman trilogy is technically for children, but as recent books such as Harry Potter have shown us, the children’s section doesn’t mean it is childish writing. While anyone can appreciate the story in these books, I think only an adult can truly appreciate what is happening on so many levels and the subtle nudges towards our own world that Pullman litters throughout the book. The story itself is about a young girl growing up privileged in a world where each person has their own daemon (literally their soul), these daemon take the from of animals and are a persons constant companion their entire lives until eventually they both die.