Darkness Visible — Mike Carey

When the demons came, humanity reluctantly learned to share the world with another sentient race. Sixty years later, this uneasy co-existence has spawned an endless terrorist conflict. Detective Daniel Aston, charged with being the thin blue line between the two sides, is tested to the limit when a demon sets up house inside his soul. But to save his daughter, he'll pay any price -- including genocide. Collects issues #1-6.