Esta é a série His Dark Materials de Philip Pullman. Cada personagem tem um indivíduo "Daemon" que supostamente representa uma espécie de espírito animal.
Por wikipedia:
A dæmon is a type of fictional being in the Philip Pullman fantasy trilogy His Dark Materials. Dæmons are the external physical manifestation of a person's 'inner-self' that takes the form of an animal. Dæmons have human intelligence, are capable of human speech — regardless of the form they take — and usually behave as though they are independent of their humans. Pre-pubescent children's dæmons can change form voluntarily, almost instantaneously, to become any creature, real or imaginary. During their adolescence a person's dæmon undergoes "settling", an event in which that person's dæmon permanently and involuntarily assumes the form of the animal which the person most resembles in character. Dæmons and their humans are almost always of different genders.
