Twin Stars - Charlotte Clutterbuck

Bhòid grasped Sulaire's hand. 'Stay behind me. Whatever happens.' She shook her head, her face a wild mask of red and shadows in the firelight, and stayed where she was. The wolves slipped out of the woods, moving over the snow in a loose pack of shadows...

Thousands of years ago in Stone-age Scotland... 

...twin brother and sister, thrall born, but with dreams beyond the Custom of the Beaver Clan. Bhòid can only become a Hunter if he shows outstanding courage in the Wolf Guard. Lamed by a fever, Sulaire fears she is no longer fit to be Healer. When Bhòid injures the Headman's son whilst protecting his sister, he must flee to an uninhabited island. Can he survive, alone and defenceless? Can Sulaire heal the Headman's son from his injuries and his inner darkness? Will the twins ever see each other again? 

Twin Stars is set on the island now known as Eilean Bhòid--the Isle of Bute--in Scotland.