Styxx

In the book, an ancient evil has been unleashed and seeks revenge on the human race. The twin to the hero who previously saved the human race is forced to prove his loyalty by trading his life for his brother's future. The heroine, an Atlantean goddess, owes a debt to the hero and vows to help him, even if it means going to hell. The two brothers must put aside their feud and learn to trust each other to save the world. But when loyalties are skewed and no one can be trusted, how can they find a way back from the darkness that wants to consume everything, starting with their own souls?