Obsidian Hearts by Linnea Fletcher

Caius has been accused of many things in his life: murderer, traitor, master of the dark arts. He would admit to being well-versed in the dark arts. As do all who take a wrong turn on the winding path of life’s experiences, he had his reasons and he learned to embrace the darkness.
Rhiannon was light to his darkness. She saw clearly, where others only saw shadows. Some speak of looking “through a glass darkly.” Not Rhiannon. Where Caius was concerned, she never saw through that glass darkly.
For the first time in his life, Caius thought he also saw through that glass clearly. From the moment he saw Rhiannon, from the first time they accidentally touched, he knew she would be his damnation.
Little did he know that glass was clouded, as she would also be his salvation.