The Fury of Dragons: A Tale of Roman Britain (Sword and Spirit #2)
Renee Yancy

Coroticus doesn’t understand why this skinny girl-child has bedeviled him from the moment he laid eyes on her. But when, on the deck of his ship, she speaks to him the identical words carved into his mother’s tomb, all he knows is he cannot let her go.
The premise of The Fury of Dragons is based on St. Patrick's fifth-century text, Letter to the Soldiers of Coroticus, in which he condemns the British chieftain who stole his converts and “gave girls away like prizes.”