One learns, while in a coma recovering from terrible brain trauma, that there is a lot of time to reflect on one's life. Even now, All for one remembers the day his quirk came in. He and his brother had been living a single step from poverty before that. It wasn't uncommon, especially then for most people to live in squalor and filth. It had been up to him to take care of Riku after their parents had died.
He couldn't dispute the fact that he resented the responsibility that had been thrust upon his shoulders. His sickly brother had been about twelve when their parents died. For a seventeen year old with no money and even less consideration, he had neglected his responsibilities to his sibling. That neglect had caused the dramatic decline in his brother's health. He regretted it immensely now, but at the time he could remember hoping that the little boy would pass quickly.
It didn't happen though. Everytime he would think oh, maybe this will be the moment he will be gone, it wasn't.
But the day his quirk came in changed things.
Their parents - worthless people, honestly- had died early in the riots. Neither of them accomplished much of anything. Their being dead simply stripped away the last paper thin shred of security he had.
Riku wasn't built for that kind of life. The boy was too soft even then. Too weak. Not willing to look at the things his elder brother had to do, even in the early days to keep them from starvation and homelessness. He had to punish the boy frequently for disobedience, and that was difficult with how ill he was.
It wasn't even love that tied him to the smaller boy. Not really, since All For One was fairly certain the emotion was simply beyond him. Perhaps a sense of moral obligation? Duty? Responsibility? He wasn't certain even now.
Where Riku had floundered in the violence, he had taken refuge. It suited him. Where other people wavered he stood firm, where others cowered he persevered, and where his brother refused to look he dominated. The seedy underbelly of corruption that covered the filthy society erected by the new supernatural race blossomed. It was natural for him to have gotten involved.
And when his quirk came in, All For One might have taken it as a sign for God, if he believed in such things. Where before the violence of a quirk-riddle society had been his burden, now it was his playground.
By the time he was twenty-two he had erected a following unlike any since the emergence of quirks. It hovered, silent but ravenous, just outside of the broader public eye, but in those days his name spread. People near worshipped him as a God.
He became cocky. It was stupid. He had dragged Riku with him through the dirt and the vomit. His stupid, frail, weak little brother. In a moment of pity he still can't manage to regret, he flicked a worthless quirk into his then fifteen year old brother's disease ridden body.
His original intention was for the quirk to strengthen his brother. It was the closest he could think of to a solution to Riku's chronic illnesses, but the quirk manifested itself differently than he had expected. Instead of bolstering his brother's immune system, it supported his physical abilities. He remembers being aggravated with the failure. Furious, perhaps. He had made up his mind to look for alternatives and so decided to take back the quirk.
Found out that he couldn't.
With the knowledge that he has now, All For One knows now that it was the reaction to that event in particular that probably caused Riku to start down the path of betrayal. In those days, his temper was more volatile than it is now. Thirty-seven of his followers were killed before his rage was exhausted, and he vaguely recalls sentencing his brother to house arrest for three months after the fact.
It didn't matter how much he wanted the quirk back, nothing he did could claw it from his brother's body. Suddenly, his entire focus was directed toward his brother and that focus was a heavy burden to bear. Riku crumpled underneath it like a piece of paper.
Or at least, All For One thought he had.
Spies within his empire stole the boy away in the night. His brother was brainwashed to believe the lies they spewed. Returned to fight him, still desperately ill despite the power the quirk he had given him granted.
Died in his arms. Only nineteen.
It was the recoil of nothing that he felt which surprised him. It was a different sort of nothing from the other deaths. He didn't like the feeling. It ached of failure. Of pain.
He buried the taste of it with his own name and that of Riku's, with his brother's eyes shining like emeralds, blood soaking his own body as the greatest villain on earth held someone who had declared themselves an enemy despite everything All For One had done for him.
Twenty-seven years later, another scrappy young thing would burst out of the woodwork holding that goddamned quirk he had cursed his brother with declaring that she would defeat her Master's killer.
She died slowly and painfully. As would the next. And the next.
It became a private obsession, but the face of the nameless carrier barely mattered. He barely dedicated the brain power towards learning their names. What mattered was the quirk. Slowly, it bled stronger and stronger as it hopped from host to host - settling finally on a woman named Shimura Nana.
It was this woman in particular who jump started what he called the Solution. While a proficient fighter, near glorious with the boost that his brother's quirk gave her, it was her mind more than anything that impressed him. That and her callousness.
He knew nearly the minute she did that a child had been born. Spies watched nearly every breath she took and so something as intriguing as that was obviously taken into account. But when she gave the baby up for adoption, All For One took notice. He learned her name. She joined the list of things to keep track of that iterated through his head like a record looping on it player.
The Solution, though, that was what was actually important. Not his brother or this woman. What was the Solution? Simple. The goal of the project was to develop a solution for the downside of his quirk. One that had irked him for years, even though he took numerous steps to hide it from nearly everyone.
That downside was quite simple to be honest. There was an upper limit to the number of quirks he could store at any one time. That limit could be increased by coagulating similar quirks, but at the end of the day his upper limit was approximately thirty, and even that was pushing his endurance to the max. His comfort level resided at eighteen. Any more than that and he'd be coughing up blood.
The problem, of course, was finding a method of storage. Quirks were fundamentally organic, and even if he could store them in an inorganic manner, he wouldn't. Not when that would make them easily accessible to enemy and ally alike. It was when he was contemplating this question that news of Shimura Nana's delivery came in.
Children had never been part of his legacy. All For One had no desire for a biological child, particularly not since it would mean more duties, more responsibilities, and primarily, what if he got attached again? His brother had proven previously that he could form attachments to people. Besides, he was functionally immortal, so the primary reason for reproduction had been irrelevant.
But now...
He decided nearly immediately that they wouldn't be children. At least, they wouldn't be his children. Instead, they would be tools he simply assisted in creating. And there would be no procreation on his end of things for this. His entire contribution to the project was a couple vials of semen, and approval at the end of the period for those with appropriate quirks.
They ended up manufacturing approximately twenty to thirty units a year. Each unit was lab grown via the stolen or donated eggs of quirkless or near quirkless women. Unfortunately, it was through this piece of the experiment that they learned how rare All For One's quirk actually was. On average, a quirk similar to All For One's own manifested perhaps five percent of the time. It was more common for the children to mutate a random quirk than to inherit his own.
It didn't matter though. On the fifth birthday of every unit, they were processed. He personally verified their quirk. Those with a quirk similar to his own were put into medical comas they would never wake up from. Those without were redirected as materials for any procedure necessary. Nothing went to waste.
Until Consume.
The moment the little boy stumbled his way into the processing room, his eyes big and green, his hair an identical color clouding around his head like dandelion fuzz All For One realizes he has made a mistake.
In his enthusiasm to protect himself, he had forgotten something. Riku was his brother. A roaring beast erupts in his chest. His head feels fuzzy, and he swallows trying to maintain his composure when all he can see is green.
The boy is near one to one with Riku, had his brother had green hair rather than a shaggy white.
"Dr. Tsubasa?" He asks, forcing himself to sound calm.
"Unit Twenty-One. Quirkless." The doctor replies unaware of the conflict rushing behind All For One's expressionless features.
He hesitates for a single moment.
It's enough.
"Retrieve Unit Twelve."
The doctor looks at him confused. "Why? Unit Twelve passed all the qualifications you set out."
All For One can't take his eyes off of the boy in front of him. "Do as you're told."
The process is painful for Unit Twelve. Ripping the quirk out of someone like this is excruciating. It shrieks loudly as it collapses to the floor, its limbs twitching slightly as its brain tries to grasp the enormity of what it has lost. He looks back at the doctor who is trying to conceal his baffled expression. "Dispose of this Unit. Immediately."
"Of course, sir."
He approaches the boy, Unit Twenty-One, who looks terrified enough that he might try to bolt. Faint whisper thin memories of comforting Riku come forth.
Did he ever actually do that?
He turns a fraction of his attention to the quirk inside him. A weaker variation of his own. This one can hold maybe five quirks at the most. It's loss as a vessel for storage is minimal, and he almost regrets not selecting a better one for his son-
Wait. He continues approaching the boy, his quirk focused forward and snorts audibly. "You have a quirk."
The boy blinks at him owlishly, though his terror is still obvious.
"I'm going to give you this one anyway." This is all spur of the moment anyway, and though the boy has a quirk- it's stupid and weak - a long range analysis quirk, something barely more relevant than looking at someone. "This will hurt." He is blunt because although something in him is willing to do anything to possess the boy in front of him, their is an equally significant portion that wants to see him suffer.
Because he looks just like Riku.
It happens near instantaneously. One moment, he is forcing the quirk into the boy and the next, Unit Twelve's quirk is running rampant through the boys system. All For One recognizes the feeling from his brother years ago, even though he didn't know what it was then.
As he had hoped. Whatever it is about All For One and his brother's quirk, the quirk he ripped from Unit Twelve is the same in this respect. It canabalizes the boy's own quirk, stuffing it past its greedy maw down into its gullet.
The boy will retain some of his original quirks abilities. Probably. Riku had after all. But it won't ever be the same.
All For One looks the little boy in the eye, enjoying the tears he blinks back as the last spasms of pain ripple through his limbs. "I'm going to call you Consume." He makes certain the boy is paying attention to him despite the wild trembling in his limbs. It wouldn't do for his son to pick up bad habits right off the bat. "You are going to call me Father."
Three weeks after the Final Battle, All For One woke up.