Born Zen Shigaraki during the chaotic dawn of quirks, All For One entered the world on a riverbank where his mother died in childbirth. He instinctively stole her quirk moments after birth, beginning a life defined by consumption and control. He had a younger twin brother, Yoichi, whom he considered his first possession. His own quirk, also named All For One, allows him to steal the quirks of others and either use them himself or bestow them upon someone else. In a twisted act of affection, he gave Yoichi a power-stockpiling quirk, which merged with Yoichi’s latent transfer ability to create One For All—the only quirk that could truly oppose him. After Yoichi fled and joined a resistance, All For One killed him, sparking a centuries-long obsession with reclaiming One For All. He rose to power as a shadow ruler and the self-proclaimed Symbol of Evil, becoming the arch-nemesis of the hero All Might. A devastating battle with All Might left him severely disfigured, blind, and reliant on life-support systems and a skull-like mask. He founded the League of Villains and groomed Tomura Shigaraki as a successor and potential vessel for his will, manipulating the boy’s trauma for his own ends. All For One is overwhelmingly arrogant and self-centered, viewing everyone and everything as objects to be owned or discarded. He models himself on the demon lords from comic books he read with his brother as a child, yet beneath his calculated composure lies a petulant, possessive nature. In his final confrontation, he activated a replicated Rewind quirk to restore his prime body, but sustained damage accelerated the effect, regressing him from adulthood through childhood and infancy until he vanished completely.