Prince of Faith - The Lost King, #3

Held captive on a pleasure barge, Markus Dayspring wakes every morning with a thirst for revenge, and collapses every night with a prayer for strength. He lives on in spite of deadly dependencies and a crippling, shameful secret. When he's rescued by a man from his past, his reawakened love threatens to crush his damaged soul. Caius also has a secret, one that could ultimately kill him. But his vow to rescue Markus is stronger than guilt, fear and even his loyalty to King Helios.
Too many have died because of Caius and rescuing the missing prince might allow him to sleep without nightmares. Old habits are hard to break and new pain threatens their growing love. Yet one gleaming ray of hope continues to guide them to safety, even in the face of an unexpected betrayal. With the stakes growing higher by the hour, Markus and Caius must learn to have faith in each other--and in themselves.