The Last Days of Magic - Mark Tompkins, Penguin Books

Aisling, a goddess in human form, and her twin Anya, unite the Celts and the powerful faeries of the Middle Kingdom. But medieval Ireland is deeply divided. Jordan, the Vatican commander, is tasked with vanquishing otherworldly creatures from a disenchanted Europe. But increasingly he finds himself torn between duty and a desire to learn about this magic. As Kings and armies gather, Aisling and Jordan must come together to try and save the deeply divided county. Loyalties are tested, betrays sown, the coming war will have repercussions even into today's world.