Firefly

Kylie Madden has a secret. She's a Harbringer, a creature of Hell said to possess unearthly powers that haven't been seen since the time of the Darkening. Too bad Kylie doesn't feel the least bit magical; ever since the horrific incident that sent her into foster care when she was 10, Kylie has studiously avoided anything that could possibly trigger her supposedly slumbering evil. Now a model influencer and a slightly deviant e-girl, Kylie travels the world, living for nothing but the next sponsorship opportunity.
When she meets Bailey Blake, however, that all turns on it's head.
Bailey is a part of a secret world, one hidden beneath our own - one where Kylie can finally learn more about her abilities and her mysterious past. But not everyone has her interests at heart in this game of cat and mouse, and with this many players, the wrong move can be deadly.