Seagrass Maggie

From the darkness of the Feast Pit, an ancient vampiric evil crawls out of the ocean caves of the Atlantic Way. They cast a village in a dark mist, trapping them in a nightmare without end, and force them to continue ancient rituals that have long ago been forgotten. There they wait.
As an infant, Maggie was abducted by the fae and a changeling was left in her place. For eighteen long years, she slaved under the rule of the fomori clans, and changed into a dreadful creature with serpent's blood. After finally escaping them, Maggie returns to her stolen life, fighting her inner-serpent's blood at every step, and hunts the changeling who took it.
But the Fomorian King wants her back.