The Stars Are Dying by Chloe C Penaranda

The brightest star needs the darkest night.' In a world abandoned by its celestial guardians and left to suffer a tyrant king's reign, all Astraea can recall are the fragmented memories of the past five years. She's determined to discover more about her past, even if that means leaving behind the only safety and security she has ever known by venturing out into a world where bloodthirsty vampires are rumoured to roam. Making her way in an unfamiliar world, she encounters the mysterious Nyte, who makes her an offer she cannot refuse. As Astraea accepts Nyte's help, she is drawn in by his darkness and she begins to wonder if she has struck a deal with one of the ruthless beings her people have always feared. Astraea's opportunity to escape this deal presents itself when she has to decide whether to take her friend's place in centenary celebrations of the Libertatem - a succession of trials hosted by the king in which the five human lands compete for safety against vampires who hunt them down to drink their blood. Is fighting for the safety of her kingdom worth more than answering questions about her past?