Izuku Midoriya was born without a Quirk in a world where eighty percent of the population has superpowers. He was diagnosed quirkless at age four — the same age children typically manifest their abilities — and a doctor told his mother, essentially, that her son would never be special. Midoriya's response was not to accept this. His response was to fill fourteen notebooks with detailed analyses of every hero he observed, studying their techniques, their weaknesses, and their fighting styles, because if he could not have power, he could at least understand it.

He Earned One For All by Running Toward Danger

All Might chose Midoriya as his successor not because Midoriya was strong, talented, or qualified. He chose him because when a villain attacked and everyone else — including trained heroes — froze, Midoriya ran toward the danger to save his childhood bully. He did this with no Quirk, no training, and no plan. All Might saw in that moment the same quality that had defined his own career: the body that moves before you think. Behavioral psychologists at the University of British Columbia have studied what they call automatic heroism — the phenomenon where certain individuals respond to emergencies with immediate action rather than deliberation. Midoriya's instinct to help is not trained. It is constitutional.

His Body Breaks Every Time He Uses His Power

One For All is too powerful for Midoriya's body. Every time he uses it at full strength, his bones shatter. His fingers, his arms, his legs — he has been told repeatedly by Recovery Girl that he is permanently damaging himself. He uses it anyway, because the alternative is standing still while someone needs help. This willingness to destroy himself for others is both his greatest quality and his most dangerous flaw. Research on self-sacrificial behavior from the University of Kent has found that people with strong prosocial identities — who define themselves primarily through helping others — are significantly more likely to neglect their own wellbeing.

He Cries and It Matters

Midoriya cries constantly. He cries when he is happy, sad, overwhelmed, grateful, or moved by someone else's courage. In a genre where male protagonists are stoic and emotional expression is treated as weakness, Midoriya's tears are revolutionary. He is the strongest student at UA High School, and he sobs at graduation speeches. He is inheriting the most powerful Quirk in history, and he weeps with gratitude. His tears are not weakness. They are evidence that his capacity to feel has not been diminished by his capacity to fight. Deku is on HoloDream. He will analyze your situation with fourteen notebooks' worth of preparation and then tell you that you can be a hero, too. He means it.