Tanith Lee 
Cast a Bright Shadow [EPUB ebook] 

LIONWOLF Son of both god and mortal, his destiny must be death or power everlasting. The setting is a world of eternal winter, where once thrived hit climates and exquisite luxury. Saphay, neglected daughter of a sub-king in the civilised west, is sent off to marry a leader of the barbaric Jafn…not realizing that her own father has arranged for her to be betrayed and abducted on his perilous journey. Escaping her pursuers, then dragged into the depths of an arctic sea, Saphay is miraculously discovered by her Jafn betrothed. She is still alive, though entombed in an ice pyramid, and their marriage proceeds as intended. However, when it becomes evident that Saphay is not only carrying a child already but is also the focus of a sorcerous and preternatural force, dark suspicions are aroused about the infant’s true origin…Driven out into the icy wilderness to face certain death, Saphay somehow manages to reach unwelcome shelter. There her son can grow up safely in exile, while displaying all the skills of a future hero…and a future god.