All for One

Once Japan's most powerful villain, and All Might's arch-nemesis, his ultimate goal was to steal One For All, the Quirk that originally belonged to his younger twin brother, and the only Quirk that can oppose him. He was the mentor of Tomura Shigaraki, having spent the young villain's life shaping him into a successor, and a vessel for his power in a plan to eventually conquer the world as a self-proclaimed "demon lord".

In the past, All For One was a towering man with a powerfully muscular physique, imposing features, short white hair, and faded red eyes that showed no sense of feeling. He usually wore a dark suit over a white shirt. When All For One left his secret hideout during the Kamino Incident, he donned a navy blue, skull-like gas mask with angular tubes at the top, a wide collar-like life-support system around his neck with additional pipes connecting in the front and back, presumably to help him breathe.

All For One was a subtle, sadistic, and malevolent man who liked to rule from the shadows and enjoyed himself at the expense of people before discarding them. In the past, All For One used his power to help people, but in exchange for their servitude. Once they could no longer follow his orders, All For One would callously abandon them, and his followers purged those who defied his will. Taking advantage of the chaotic era caused by the uprising of Quirks, All For One offered people anything they wanted as long as they followed him, including choice and power to those who had none, where he would take Quirks from those who didn't want them and gave Quirks to those who wished for strength, all as a means to gather numbers and conduct his schemes through other people. He masked his true intentions by claiming that he just wanted to help restore order and balance to society.

All For One exhibited extreme megalomania and even traits of an outright God complex, having compared himself to the Demon Lord he read about in comic books. He also relished his total power over Japan and saw himself as a higher being. All For One would steal the most powerful Quirks during his rise to power and crushed anyone who stood in his way.[12] He also displayed signs of kleptomania, claiming that he couldn't resist stealing a powerful Quirk when the opportunity presented itself.[13]

The only person All For One seemed to care for was his younger brother, Yoichi, as he was his only family. However, All For One regarded Yoichi as his possession and was condescending towards him for his frail body, even kicking Yoichi for standing in his way. He was also exasperated by his brother's ideals of justice and attempts to stand in his way.[14] All For One had a firm contempt for ideals of justice and morality, dismissing them as arbitrary beliefs of other people that shackle personal freedom.[15] Like All Might yearned to become a symbol of justice, All For One sought to be an all-powerful evil, inspired by the comic books he read with Yoichi in their childhood. His ultimate goal was to use his power to thwart humanity's future and rule above everyone, as it fit with the "Demon Lord" character he envisioned himself as.[8]

Ever since he was born, All For One was already quite selfish, arrogant, and had a discerning lack of empathy. Having been forced to survive in a chaotic era caused by the emergence of Quirks, he believed those who didn't help him deserved to perish, using the Quirk he took from his deceased mother to kill people while stealing their abilities. While his weak younger brother had nothing to offer him, All For One still kept Yoichi around as he felt as though he belonged to him. After being inspired by the Demon Lord in comic books, with how the fictional evil being reigned supreme and ruled through fear, he soon came to dream of a world that would submit to him, leading him down his evil path.[16]

Even when his brother rebelled against him, All For One kept Yoichi alive and imprisoned him, hoping that if he gave his seemingly Quirkless brother a power of his own, he would join his side. When Yoichi chose to flee with Kudo and Bruce however, All For One proceeded to locate and kill him, seemingly bearing no remorse for the act. According to Yoichi, All For One only saw people as playthings or as prizes to win, and in the end, even his own brother wasn't exempt from his possessive and dominant nature. Upon learning of One For All's creation, he became obsessed with claiming his brother's Quirk and would go on to pursue it for many decades, wanting to regain his little brother and finally be able to possess him. In a twist of irony, All For One ended up creating the one Quirk that he couldn't steal, and along with it, generations of heroes who were sworn to fight and put a stop to him.

All For One was a patient mentor towards Tomura and often gave him constructive criticism and encouragement, even when the latter failed. Upon finding him all alone as a child, All For One took him in and gave him a room of his own while becoming his "Sensei"/"Master," going as far as to rename the young boy while giving him his surname, demonstrating a seemingly caring and even fatherly side. However, All For One only viewed Tomura as a mere vessel for himself, revealing that his reasons for raising him were purely for his own gain. All For One exploited Tomura's traumatic memories of his abusive father and groomed his rage so that he could use it as a tool to overwhelm the willpower of One For All and finally be able to steal the Quirk.

All For One despised those who persistently defied him, especially the users of One For All. He loathed All Might in particular for ruining his syndicate and crippling him. He was also a firm believer in the hatred of the heart, having believed it to be a very strong source of power. When mentoring Tomura, All For One gave him the hands of his deceased relatives as a way for the negative feelings in his heart to remain close while also giving him a sense of comfort.

As much as he encouraged Tomura's hatred, All For One was also highly derisive and mocking towards his enemies as a means to get under their skin and/or cause them to drop their guard. His taunts and expertise in psychological warfare were enough to enrage even the strongest heroes, such as All Might and Endeavor. Even when outnumbered, All For One remained unshakably calm, willing to slaughter enemies with his tremendous power. He often regarded lesser opponents as fodder rather than actual threats, though he was ready to take an interest in their Quirks to see if they were worthy of taking for himself.

Due to his immense power and confidence, All For One had a calm and condescending demeanor. Thanks to a combination of Quirks, All For One was able to detect lies and hostility, with which he could preemptively eliminate traitors.[20] Due to his long life, as well as his status and experience, he was well-informed about almost every significant figure among heroes and villains.

For his malevolent nature, All For One presented himself as polite, sympathetic, and generous towards his associates and underlings, often seeming amicable and fair-minded. However, this was only glib that All For One employed to subtly manipulate people into following his bidding, showing no concern for them once they were captured or outlived their usefulness. All For One admitted to Dabi that he sees people as nothing more than disposable tools - should they fail him, he shrugs and moves on to the next alternative, though he was willing to take enjoyment in when they received their comeuppance, be it from him or someone else. Even if his followers failed him, All For One admitted that it was worth seeing what entertainment they could bring before their downfall and would even tempt someone into helping him before sadistically watching them suffer, showing his twisted willingness to toy with people's lives while having a blatant disregard for whatever happens to them.

While All For One was completely selfish, he was willing to die for his ideals and would not spare any effort to ensure that his idea of a Symbol of Evil would continue even after his death. While he wanted to possess Tomura's body for his own ends, All For One didn't seem to mind if Tomura managed to kill him as long as he continued his legacy.

As a side effect of his own Quirk, All For One explained that he often suffered from nightmares where the people from whom he stole Quirks appeared in his dreams and hurled insults at him. Despite his remorseless personality, All For One admitted that such episodes sometimes left him feeling very discouraged. However, he scoffed at the idea of being able to feel guilt, as he believed it to be a trait of inferior humans.[23] As further proof of his detachment, he repeatedly denied blame for any of his actions, instead laying the fault on his followers who only wanted to support him or who otherwise sided with his plans for their own reasons. He did this despite the evident fact that he had manipulated all parties involved into acting on his behalf with honey-laced promises while also taking advantage of their personal and emotional vulnerabilities to coerce them into enacting his will, persistently refusing to admit that he was to be held responsible, while at the same time, gloating about his results and his alleged power to achieve his goals, grinning with hypocritical delight. While it was initially believed that his followers carried out his orders out of loyalty to him, it's revealed that some obey him out of fear of reprisal, a strong rebuttal of All For One's belief that his supporters acted out of their own will and possible evidence of either a deluded sense of support to his ideals, or downright despicable lies to deflect blame