Game of Blood

"Street thief Irma is one execution swing from death when Crown Prince Lukian, dying from a curse only black blood can ease, buys her life as his blood source. His touch heals him without pain or blade, which is a resonance no one can explain. Her trust shatters when she learns he let her best friend die feeding the same ritual, then shatters again when she uncovers his icy fiancée Rina's secret: decades spent killing black-blooded women, including Irma's mother, to fuel stolen immortality. When Irma exposes her, Rina strikes first, framing her for murder and seizing the crown."