Tanith Lee 
White Serpent 

HE WHITE WITCH – She is Aztira, one of the magical Amanackire race, a pure white albino with powers both mysterious and terrifying. She can grant life and defy death, enchant men – or destroy them!AND THE WARRIOR – He is Rehger. Sold into slavery at the age of four, he will become one of the finest warriors and charioteers in the land. Yet all his prowess with arms will not save him from the spell of the White Witch, a dangerous bewitchment that will lead him to challenge the mightiest of mortals and immortals … and to embark on a fearsome quest in search of the legendary city that is home to the Amanackire.