Deeplight

In the world of the dead gods, fifteen-year-old Hark discovers the still-beating heart of a terrifying deity in the wreckage of the ocean floor. When he decides to use this dark artifact to save his critically injured best friend Jelt, he must protect it from smugglers, military scientists, and a fanatical cult who want it for their own purposes. But as Jelt begins to transform in unsettling ways, Hark faces an impossible question: how far should loyalty extend when the person you're saving is becoming something monstrous?