The Nereids are sea nymphs of the Mediterranean. It was said there were fifty of these daughters to Nereus and the nymph Doris, and they lived with their father in an underwater dwelling. These young and beautiful maidens were also part of Poseidon’s retinue. They either had lovely blue hair, or striking golden hair, depending on what you read. Individually, they are also said to represent various aspects of the sea: foam, brine, currents, shores, etc. Unlike some mermaid and siren myths, the Nereids gave aid to sailors and fishermen and were therefore worshiped in port towns.
Art often depicts them riding various sea creatures, from dolphins to sea monsters such as Cetus. In addition to having power over the sea, they inherited the ability to shape shift from their father.
Thetis is the most famous and sometimes called the leader of the Nereids. Peleus sought her for a bride and managed to capture her. She changed shape repeatedly, becoming water, fire, a lioness, and a serpent, but still Peleus held fast and did not let her go. So, she finally consented to marry him. Later, she gave birth to Achilles.
For more information and images of the Nereids, you can check out theoi.com.
In Elemental Magic, Aileen begins having visions of her deceased mother. She chalks it up to stress, until an encounter with a sea dragon—Cetus to be precise—has her questioning if perhaps her mother wasn’t human like she thought. And if she’s the half-daughter of a Nereid, what does that mean for her?