In The Changeling Sea, author Patricia McKillip explores the different permutations of love. She examines conventional love of a woman and man (the king and his queen); she examines the love between an exotic sea-creature and the king; she examines a love between a woman and her lost husband (Peri's parents); and she examines Peri's adolescent love for the prince of the sea. All these different types of love are somehow incomplete. Each of them is slightly "unnatural," the woman is either asked to change or becomes obsessed with her love-object.

For McKillip, it is only the last love — the love of Peri and the Magician Lyo that is pure and fulfilling. Unlike the other women, Peri does not lose herself in her love for Lyo. She remains herself. She is Lyo's equal and both characters know it.