He swore to the heavens. On blood. On his brother's lifeless body. Zhou Yi Chen vowed to kill the demon Zhu Yan - the ancient calamity also known as Zhao Yuan Zhou - the being who shattered his family and burned his world to the ground. As the last descendant of the Bing Yi clan, vengeance was not a choice. It was destiny. But destiny has a cruel sense of humor. Because the demon he hunts does not resist him. Zhu Yan watches him with eyes that are far too gentle for a creature who has lived for thirty-four thousand years. He shields him in battle. Bleeds for him. Stands between him and death without hesitation. And when Zhou Yi Chen demands to know why- The demon only smiles faintly. "You swore to kill me," Zhu Yan murmurs. "Then I will die by your hand. No one else's." The wilderness is no longer safe. Forced into an uneasy alliance, Zhou Yi Chen must fight beside the very demon he vowed to destroy. But there are dreams. Fragments. A past life where cold hands once held him like something precious. A past where Zhou Yi Chen was not a hunter - but a lover. And Zhu Yan was not a monster - but his. The closer they stand in battle, the harder it becomes to ignore the way the air shifts between them. The way Zhu Yan's voice softens for him. The way Zhou Yi Chen's sword hesitates at the demon's throat. If they fall in love again... Will the heavens demand blood? Or will fate break first? Because a vow sworn to the heavens cannot be undone. And loving a demon always comes at a price.