Sangre de Dragón: Las Cuatro Llamas

In ancient Aetheran, dragonborn royalty rules seven kingdoms—but a thousand-year curse causes purebloods to die before age one hundred, with heirs growing rarer each generation. Princess Elena, from a fallen noble house, sells her bloodline at a sacred ritual to save her dying mother. There, Crown Prince Drake discovers her. Mistaking her for a gold-digger, he completes the ancient "Dragonflame Union" with her out of desperation.