Daughter of the Wind — Michael Cadnum

A young warrior sets out to rescue a Viking princess

On the frosty coast of Scandinavia, the greatest warriors are the berserkers -- men chosen by the god Odin to perform superhuman feats of strength, obliterating their enemies with the frenzied passion of a wild bear. More than anything, Gauk wishes to join their ranks. On a hunting trip in the blighted North, his best friend is slain by a bear, and Gauk is forced to kill the great animal. As he dons the pelt of his victim, Gauk fills with Odin's spirit, and knows that he is on his way to becoming a legend.
 
When the most beautiful princess in a Norwegian village is kidnapped by a pack of bloodthirsty Danes, Gauk knows it is his destiny to rescue her -- and neither ice nor ocean nor an enemy's steel blade can keep a Viking from his destiny.