The Merman’s Children belongs to the middle period of the writing career of the prolific Poul Anderson. Although Anderson has produced more science fiction than fantasy, this text is indicative of his abiding interest in mythology and magic. The book is divided into sections named after such mythical creatures as Kraken, Selkie, Tupilak, and Vilja. It is a medieval fantasy, unusual for its Scandinavian setting but nevertheless dealing with the popular theme of the fading of Faerie from the world with Christianity’s overwhelming rise to power. Although basically a Catholic variant, the Christianity of the novel is strongly laced with assorted superstitions, myths, and fairy tales of the type associated with the folk ballads of fourteenth century Scandinavia.
The dominant motif of this conservative novel is the importance of the Christian soul, although there is some irony in the excessive piety of the converted merfolk, particularly of the merman’s daughters, Yria/Magrete and Eyjan/Dagmar, who give up their faerie freedom and immortality for a much more restricted life, death, and salvation. Curiously, contact with humanity creates situations in which the merfolk themselves are responsible for driving other creatures of faerie from the world: Tauno, Eyjan, and Kennin kill the Kraken of Avernorn; Vanimen and his warriors drive the Vodianoi from his lake; and Tauno destroys the Tupilak. The novel ends on a note of heretical piety, when Father Tomislav suggests that Christianity ultimately will be completely victorious when, on the Last Day, everything that ever lived (including the unrepentant Tauno and his faerie bride) will be resurrected in Heaven.