Between the Blade and the Heart by Amanda Hocking
Game of Thrones meets Thor: Ragnarok in Between the Blade and the Heart, a gripping story of love and revenge from Amanda Hocking, author of the Trylle trilogy and the Kanin Chronicles.
Malin is a Valkyrie-in-training. It's her responsibility to slay immortals, returning them to the afterlife to maintain balance in the world. She also struggles to maintain balance in her own life - between her studies, her duties as a Valkyrie and her conflicting feelings for her ex-girlfriend.
But when a beguiling stranger breaks into her home on a quest for vengeance, Malin's carefully balanced life falls apart. Asher is hunting the rogue immortal who murdered his mother, and he thinks Malin may have information. Her loyalties are tested, as she uncovers a betrayal that unravels everything she thought she knew. And she must decide if helping the mysterious Asher enact his revenge is worth the risk - to the world, and to her heart.