Autumn's Alliance (Celtic Faerie Tales) by J.C. Wade

Rival courts. Dangerous vows. A love neither of them can afford. On the wind-scoured moors of Scotland, Isla has always dreamed of more than goats, geese, and bare survival. But her family carries a dangerous secret: generations ago, a bargain with the fae left their blood forever touched by otherworldly power—one the Unseelie will do anything to snuff out. When desperation forces Isla to strike a hasty deal with Soren—a sharp-tongued, maddeningly handsome faerie sworn to protect his sister from a tyrant’s grasp—their fates become entwined. He longs to save his sister; Isla longs to escape the web of bargains and debts that bind her line. But in Faerie, every alliance carries a price, and even love can become a trap. As shadows gather and rival courts edge toward war, Isla must choose between the fragile safety of her mortal life and the perilous freedom of claiming her own destiny. Read more