The Dragons of the Rhine — Diana L. Paxson

Throughout the long winter, the Wolf and the Raven shared the warmth of their hearts and bodies. And when the time came for parting, the noble Wolf swore he would soon return for his beloved...

The Dragons of the Rhine welcomed Sigfrid Sigmundson to the court of the Burgund--and then bound the fabled warrior and shapeshifter to their royal circle by insidious magic. A champion much-changed and in disguise, he has now come back to his loyal Brunahild--to best his devoted lover in combat and win her for another man. But Brunahild is Walkyrja. And though cruelly betrayed and sick at heart, she whom the High God Wodan himself has called "daughter" will not allow despair to defeat her--as she seethes and aches ... and plots her revenge.