The Gathering Storm by Lucy Varna

Born a Viking and an immortal warrior of the People, Sigrid Glyvynsdatter has spent her entire life chasing wars and men, not necessarily in that order. Now one of the People’s leading geneticists, she longs for the thrill of battle and the spoils of war. Even her work on the recently discovered Bones of the Just isn’t enough to break the routine boredom she’s fallen into.
Until Will Corbin snags her attention with a stolen kiss.

Will has been watching Sigrid from behind the bar of his parents’ pub since she walked through its doors two years ago. In a fit of exasperation, he dares to kiss the woman he’s wanted for so long, risking her wrath and his life.
But will that one kiss lead to something more, or will the forces aligned against them destroy the fragile attraction stretching between Will and Sigrid before they can fall in love?