Reborn to Tame a Monster

In past lives, Sierra Chase, Julia Jenson, and Seraphina Nightingale's bullying of Kai Lennox led to his death, triggering the Eternal Dark apocalypse. Reborn, the three protect Kai Lennox, discovering the Thorne father and son murdered his parents and experimented on him. Kai Lennox survives a fall, awakens shadow and monster control. After revenge, he becomes the strongest in the apocalypse, guarding humanity.