Faun's Labyrinth: Pan's Journey by Alfaguara Juvenil

A dark and magical novel, an unforgettable collaboration between two of the most renowned storytellers of our time: Guillermo del Toro and Cornelia Funke. In an underground realm, where lies and pain did not exist, a princess dreamt of humans. One day, she fled to our world, the sun erased her memories, and the princess perished, but her spirit was immortal. The king would not concede defeat: he hoped that his daughter would return home someday, in another body, in another time, perhaps in another place. He would wait... until his final breath, until the end of time.