Valhalla - Ari Bach

Valhalla: Book One
Violet MacRae is one of the aimless millions crowding northern Scotland. In the year 2230, where war is obsolete and only brilliant minds are valued, she emerges into adulthood with more brawn than brains and a propensity for violence. People dismiss her as a relic, but world peace is more fragile than they know.
In Valhalla, a clandestine base hidden in an icy ravine, Violet connects with a group of outcasts just like her. There, she learns the skills she needs to keep the world safe from genetically enhanced criminals and traitors who threaten the first friends she's ever known. She also meets Wulfgar Kray, a genius gang leader who knows her better than she knows herself and who would conquer the world to capture her.
Branded from childhood as a useless barbarian, Violet is about to learn the world needs her exactly as she is.