Tarnished (Caged #5.5)

Sean has a reputation for brutality, and it is well-deserved. Centuries of inflicting pain and punishment on anything and everything he deemed worthy slowly stole whatever light had been in him when he was born. His angelic nature fell victim to the god of war within him, just as Ares had intended.
After an enigmatic encounter, a vision of Ruby comes to Sean and changes all of that. Her piercing blue eyes bear their way into his soul, awakening it as though it had never slept. Struggling against his inner darkness, Sean fights to keep that light from fading again and eventually goes to extremes to ensure that it won't.