Unknown 66

Ty and her little brother Colt have been each others only friend since before they can remember. They can't have many friends in their lifetime. Why? They're the supernatural children of ancient supernatural creatures- who are also murderers of humanity. But they're not the only ones. One night Ty and Colt are caught trying to escape from the city and are put in Paragulous City Imprisonment with other children who have tried to escape before. With the help of her new supernatural friends, Ty and her 'Unknown 66' escape the imprisonment, but must survive on their own while fighting off deadly teenage assassins, uncover clues about all 66 Unknowns, save humanity, all while trying to find a way to defeat and ultimately kill their parents.

Before they kill them.