Immortal Brotherhood Series by Lisa Hendrix

He came to England in search of treasure. Two hundred years later, he's found her...Ivar Graycloak is a brave warrior, a man known for his strength and integrity. He is also a man with a terrible secret. Long ago he was part of a Viking crew cursed by an evil sorceress to live for eternity as were-creatures. An eagle by day and a man by night, Ivar has lived a solitary existence for over two centuries. Then the king orders him to marry.
Lady Alaida is everything a man could want in a bride—intelligent, spirited, and beautiful--and their wedding night is a balm to Ivar's lonely spirit. Then a seer brings him word of a dark vision, one that makes Ivar vow to stay away from his lovely wife forever. But now that Ivar has sampled Alaida's passion, her humor and warmth, he is enthralled. His traitorous body—his very heart—longs for that which he can never possess.
Lady Alaida may surprise him yet, though, for she has a power of her own—a power that will either destroy everything they hold dear or ultimately set them free…

An Immortal Brotherhood novel.
For centuries he's hidden in the woods. Now a maid has come to lead him out...

It's been four centuries since Steinarr the Proud was cursed by a wicked sorceress--along with the rest of his Viking crew--to live for eternity as half man, half beast. By day Steinarr is like any other man--by night he is a lion. He has taken refuge in the woods of Nottinghamshire, England, and there he encounters two young travelers, Robin and Marian.

Painfully aware of the danger he presents when the moon rises, Steinarr initially refuses to help them search for the key to Robin's inheritance. Then a kiss from Marian awakens his desire. Driven to protect the maid he so desperately wants to possess, Steinarr joins their quest...while the sorceress Cwen gathers her dark magic to destroy them.

As a legend spreads of an outlaw in the woods, their band is joined by others. But it is Steinarr who has the most to gain and the most to lose--if he is ever to be free of the curse and free to love as a man...

Part of a cursed Viking crew, Gunnar the Red must toil through eternity as a half-man, half-beast. Only the magic of true love can release him. Though she is betrothed to another, could Lady Eleanor de Neville be his salvation?