Fathomless

Celia Reynolds is the youngest in a set of triplets and the one with the least valuable power. Anne can see the future, and Jane can see the present, but all Celia can see is the past. And the past seems so insignificant -- until Celia meets Lo.
Lo doesn't know who she is. Or who she was. Once a human, she is now almost entirely a creature of the sea -- a nymph, an ocean girl, a mermaid -- all terms too pretty for the soulless monster she knows she's becoming. Lo clings to shreds of her form...