Warrior Tithe: Faerie Tales

Aoife, a kelpie, spends her days bringing mortal evildoers to their watery deaths. How does she know they're evil? Whatever you imagine, whatever memory pops in your head, she can see it.
Her father, Mannan mac Lir, god of the sea and ruler of the Folk of the Sea is tired of Aoife’s vigilante justice--he’s losing the faith of the fisherfolk humans because of his daughter’s exploits. His solution is to wed her off to Cu Roi Mac Daire, making Aoife his problem.
Aoife sees through Mannan and Roi's plot. Her sisters help her escape the trap the king and their father lay for Aoife to force her into marrying Roi without upsetting the Folk of the Sea. Aoife flees all she’s known to seek refuge with Mab, Queen of the Sidhe. On her way there, she is caught in another kind of trap.

Fagan is a cottar's son, who has lost his family to hard times. After burying the last of his kin, he has nothing left to live for and hope is an ember long gone cold and hard. That is, until he finds a kelpie caught in an iron snare. Seeing the poor thing suffer proves his heart is not dead. Fagan decides to save her, even if it means forfeiting his life.

Led by the promise of immortality and knighthood, Fagan travels with the kelpie Aoife through Alba and faerie with high hopes of becoming a fae knight like the legendary Tam Lin. He also secretly hopes this will make him worthy of the beautiful Aoife.

However, Aoife's intentions for bringing Fagan aren't entirely altruistic and her betrothed won't let her get away so easily. Secrets threaten to split the unlikely pair before the fledgling dreams can take root.