“They were no one. That is, they were the daughters of a poor shepherd. Born sickly, and as daughters not worth saving. Not worth the granting of names. He left the infants on a cliff beside the sea, intending they would die there. But Proteus, the herder of seals, found them and carried them back to his cave. They nursed on seal’s milk, and he raised them as his own.”

Luce was fascinated. “But if they changed when they were babies weren’t they stuck being larvae?”

“They had not yet changed. They were still human girls. Girls raised half in the water and half onshore, their father a sea god, but human.”

“But then . . .”

“Proteus raised them until they were adolescents and then gave them a choice. They could return to the human world and marry, or they could remain as creatures of the sea, both gifted and tasked. The Twins had pride, being the adopted daughters of a god. They refused to return to the people who had treated them as filth to be cast away. The sea was enough.”

Luce wondered if that meant there was something wrong with her. She couldn’t honestly say that the sea was enough for her, not when she longed for Dorian’s love as well. Even her singing wasn’t truly enough. “So that was when they changed?”

“Yes. Proteus is a shape-shifter, and he chose for them a form that embodied their history: half human and half of another world, needing both air and salt water to survive. He gave them their voices and their beauty as his gifts, their enduring youth, and the promise that other girls turned cold by human cruelty would have the same chance of finding the sea. He described the timay they would live by. Along with these gifts he gave them the task of avenging their own wounds and also all those girls who are not saved in time.”

“So they didn’t mind?” Luce asked a little breathlessly. “Killing people?”

“They were delighted. Why would they pity humans? When I knew them, they were fierce with the hunger for ships. “We let none escape. Only once did a ship elude us, when a captain stuffed wax into the ears of his crew while he stayed bound tight to the mast.”

It took Luce a second to process the implications of what Nausicaa had just said. “When you knew them?” Luce shrieked. She couldn’t doubt that Nausicaa was telling her the truth. “Nausicaa, you knew them? Like, you were in the same tribe?”