Dragon of Denmark by Jennifer Ivy Walker

Skårde the Scourge, bastard son of the Danish king Harald Bluetooth, is a fierce Viking warlord who earned the prestigious title Dragon of Denmark through victorious battles and lucrative Viking raids. When his royal father announces that Skårde will forge a Viking alliance through an arranged marriage to the daughter of Richard the Fearless, the Dragon of Denmark considers the voyage to Normandy an infuriating banishment.
Illegitimate daughter of Richard the Fearless, the Viking Duke of Normandy, Ylva is a Druid priestess and Celtic healer with the otherworldly gift of sight. She learns that she must leave her Breton village behind and travel to Normandy, where she will marry the Viking brute that she has foreseen in a terrifying vision.
When the Frankish king, determined to drive the Vikings from Normandy, attacks and seizes Richard’s clifftop fortress, the Dragon of Denmark must ally with Ljósálfar Light Elves, a Viking völva with powerful seiðr magic, and a vitki– a shapeshifting sorcerer who can assume the form of a falcon–to reclaim the ducal palace.