Chapter 3-4 of the Death and Rebirth arc reveals that Zayne is the Dawnbreaker — a vigilante figure the Spacepedia describes as eliminating Alterum-mutated humans in Linkon before law enforcement can respond. The Dawnbreaker identity is tied directly to his worsening nightmare cycle and the black ice crystals that have been spreading across his body, accelerated by the events of the Chansia arc where he absorbed MC's crystals into his own chest. The Dawnbreaker reveal is one of Zayne's single largest late-arc identity disclosures, connecting the medical prodigy, the nightmare sufferer, and the vigilante into one person.