Reclaimed by the Immortal Viking Wolf. Twilight of the Gods, #1

Bryn is many things-valkyrie, shieldmaiden, raven-shifter, horse trainer-but she's only been a fool for love once. And it had cost her mortal life. She'd done her best to put that stupidity behind her when she'd died a thousand years ago and was reborn an immortal warrior who serves the goddess Freya. Now Bryn hides amongst humans, content with her quiet life in the stables. The goddess hasn't called for her help in a century or more and that suits her just fine. Her peace gets blown to bits when Erik Siegfried shows up on her farm.
Of course, it has to be him. The man who'd turned her world upside down, betrayed her, and shredded her heart all those years ago. Wolf-shifter Erik doesn't want to be there any more than Bryn wants him there, but he has no choice. A prophetess had come to him the week before, telling him the end times are coming now-and he needs the aid of a shieldmaiden to win the battle. It's always been his destiny to fight alongside the gods and defeat the monsters that want to rule Earth.
So, he'll take any advantage he can get, even if it means dragging Bryn kicking and screaming into the fray. What he doesn't expect is to fall as hard for her as he had so long ago. The passion explodes between them, a fire that time has never quelled. But no one cares about warriors' hearts, not when the world is depending on them to win. Even if they pay with their lives. Again. Note: this book was previously titled Viking Fire.