Nightblood

Ruby is determined to protect mankind from the shadowy wraiths intent on consuming the spirit of every single human. While being the heir to the fire throne who happens to be in love with the Frost King would be a big enough challenge, Ruby has come to the realization that she might also be a Nightblood. Now she must unite the Frostbloods and Firebloods and stop the shadows before it's too late.