" When he was hidden in shadows, he looked up at the night sky. He had no choice. He pressed his hands against his forehead, trying to think of another possibility. There was none.
He wiped at the hot tears stinging his eyes, then slowly he lifted his arms to the fathomless black sky. He could endure anything if he knew Serena was safe. Anything.
"Father of night and evil, I call you." A primitive vibration trembled in the air. He knew the Atrox was near.
"Allow me to cross over and become your servant again."
A deadly cold throbbed through him with the ancient rhythm of evil.
"I come freely," Stanton added and felt something collapse inside him. "Take me back to the night."
Spears of lightning crackled across the sky and a concussion boomed through the earth, releasing the sulfurous smells of hell. Then a raven-black cloud seeped up from the ground and hovered around him.
Stanton held an image of Serena's face deep inside him as he breathed the icy spirit of the Atrox back into his body. The chill seeped deep inside him, wintry tentacles reaching down to his bones. The Atrox embraced him and welcomed him back to its congregation. Its raw power surged through him and when Stanton opened his eyes, he again ruled the night.
The world around him seemed sharper now, as if he could see in the dark. His pain was gone and in its place he felt a dark joy. He grinned as the wild rapture seized him. This time he was no longer invitus. Evil pulsed through him without guilt or worry, consequence or remorse. He breathed in the feel of it, then leaned back and became a black mist, hissing into the air. "

― Lynne Ewing , The Sacrifice (Daughters of the Moon, #5)