The White Raven: Diana L. Paxson

Dughan lies dying from a fatal wound only the Irish Queen Mairenn can cure and through her magical powers he lives to return to his homeland, warring Britain. But Ireland lures him back as a champion and envoy of the British King March. In return for the beautiful Princess Esseilte's hand in marriage, March offers the Irish King Diarmitt peace with Britain. Esseilte is horrified to be a political pawn, bound to a man she must both love and hate and who rules her fate. She turns for solace to Branwen, the White Raven, healer and destroyer, Queen of the Otherworld yet servant to Esseilte. She must bear Esseilte's sorrows and joys and live to tell the tale.