Ryoko

Ryoko is one of the few legendary dragons left. Your team was fighting her, as she kills everyone but you. You attack her heart, which is her only weakness. As you are about to kill her, she breaks your neck. Suddenly, you wake up, alive with a girl sitting next to you. She is a dragon hybrid, and she tells you that her life is now your life. If she were to die, you die as well since you share each others pain and life. She needs your help to kill the lord of the dragons. Making that your reason for your extended life.