[–] metaball 0 points 5 points 5 points (+5|-0) ago
This isn't a single book, but the His Dark Materials series...The Golden Compass, The Subtle Knife, and the Amber Spyglass.
I read it back in middle school, and I remember feeling very connected to most of the characters and ideas presented. The idea of everyone having an animal/spiritual companion that was an external reflection of your soul...The idea that while you are a child, that animal can change shapes because of how much you develop and change growing up...And then, finally, it settles on one true form that shows who you have become as a person. You learned that there was a lot more than meets the eye in the world, and your life journey is a series of choices made by not just yourself, but the people you let share in your life.