The Pendragon Wytch by C.C. Davie (The Pendragon Chronicles #1)

As long as I can remember my shadows have whispered to me, speaking in a voice both young and ancient. I have learned to mind them, let them guide me through life even when I do not understand their messages. They whisper now to me, a song of sorrow and heartache that weaves itself around the woman I love. A song I do not want to listen to, yet know I cannot run from.
King Arthur has taken this land. Aided by his advisor Merlin and the legions he commands, he has swept over this once prosperous Kingdom like a plague, chasing the last of the Sylvyns into the far south in his quest for power.
They have nowhere to run now, there is no further to go and I fear the bargains that will be made to protect them are ones that will haunt me for the rest of my immortal life.

I was born touched by Nimmet, both a blessing and a curse.

— Morgana