Chapter One: Arrival

All for One didn't call himself a king, but he ruled over Tartarus in everything but name.

He despised the wretched humans that had exiled him from known civilization for all eternity, but he remained far from a misanthrope. His time spent here taught him three things: desperation led to people being easier to control, control over their necessities directly equated to power, and power meant nothing without force to back it up. All of those facts had proven true time and time again as he'd made a name for himself, building his legacy off the bones (and magic) of others.

He was sure a portion of the population despised him, but they had the good sense not to speak of it aloud. Tartarus, once incapable of sustaining human life, flourished under him. At first, he'd been nervous that those who had sent him here would put a stop to his reign, but that proved not to be the case. As far as he knew, Tartarus worked on the principle of out of sight, out of mind. And now, everyone outside Tartarus likely believed him dead; he'd been sent here almost exactly two hundred years ago, after all.

At the moment, he was helping repair a shack that represented a casualty of a gusty thunderstorm several days earlier. Whilst carrying a huge sheet of metal with ease that others would struggle to lift, he found his path suddenly blocked by a short woman with close-cropped purple hair, staring at him with fear she failed miserably at hiding.

Seeing no need for wasting time, All for One set down his burden and made eye contact with this new obstacle. "Why do you need to interrupt me, Izumi?"

"It's Yuma," Izumi said. "He wishes to speak with you."

All for One nodded. "Thank you for notifying me. Bring him over."

Izumi darted off in response as All for One returned to work. Four sheets of metal later, she returned, this time with Yuma standing by her side.

All for One had taken a shine to Yuma almost instantly after meeting him; he feared nothing and had no qualms about spilling blood, acting as an enforcer for All for One as soon as he'd set foot on Tartarus. His magical capabilities helped in that regard, allowing him to turn any object into a deadly weapon with ease by hardening it until it became either a bludgeon or a blade. Fifteen years had passed since they'd met, yet Yuma showed no signs of slowing down: on the off chance he ever decided to retire anytime soon, Yuma would be first in line to succeed him.

Now, however, he could show no such favoritism: Yuma was here because he had a job to do. "What is it, Yuma?"

"There's a boy," Yuma said. "Rin found him washed up on shore. We're not sure how he got here or why he's here, but…"

"Show me."

Yuma stiffened, nodding so fast it was a wonder his head didn't fall off. "Yes, sir. Follow me."

Another reason All for One liked Yuma: despite his considerable talent and bloodlust, he knew who was in charge.

All for One strode confidently in Yuma's wake, their trek taking them across the entire island to its northernmost tip. Past the farmland he'd made possible, past the ramshackle village he'd helped build, past the metalworking facility he'd put together, all the way to a calm beach that rarely saw any visitors. There, he found Rin, a wraith of a man with an affinity for all things green, kneeling over a figure lying in the sand while drenched in sweat. Once Yuma called out that All for One had arrived, though, Rin made space, giving All for One a clear line of sight as he approached his target.

Once All for One neared, he took note of the newest Tartarus resident under his command. He was, indeed, a boy, one who couldn't have been older than six. Nothing about him stood out as impressive at first glance: he was of average size, his clothing was simple, and he carried no mementos or distinctive anatomical features like certain other Tartarus residents. His hair was shaggy and caked with sand, the cleaner portions of it the color of the sky. His eyes were the most distinctive part of him by far, their irises a bloody red, while the rest of them had turned the same color from crying.

When All for One made eye contact with him, the kid jerked away, seemingly out of reflex. Freezing in place like a rabbit before a snake, his eyes darted in a dozen different directions, searching for an escape route that would never come.

His first words to All for One were soft and weak, with an added squeakiness to them like that of a newborn kitten. "Are you going to hurt me?"

"No," All for One responded, trying to sound sincere. He had no reason to hurt the child yet, though if he got attacked he claimed no liability for anything that happened afterward.

The boy's fearful expression didn't change in the slightest. "Why should I trust you?"

All for One composed himself again for a second before responding. "Everyone else on this island trusts me too. If you're not going to trust me, you can't trust anyone else here, either."

"He's not lying," Rin added. "Yuma and I both trust him with our lives."

Yuma smacked the back of Rin's head. "I can speak for myself, Rin."

"Say that when you can tell Izumi you love her, you dummy."

"Maybe I would if you ever got around to telling Aoi to shove off. You both hate each other, why are you still together?"

Maybe the devolution into more casual banter helped soothe the boy. While he still looked a split second away from trying to bolt, he met All for One's eyes again, quietly observing the events unfolding before him. "I'll trust you a little, then. Please don't hurt me."

"I won't hurt you as long as you don't try and hurt me," All for One replied. "I think that sounds fair, right?"

The boy nodded.

"I'm glad you trust me now," All for One said. "Can you tell me your name?"

"My name's Tenko," the newly-identified Tenko said. "What's your name?"

"I'll tell you later," All for One said. "We're going to take you to our home. From there, we'll decide what we're going to do with you."

"There's nowhere else to go, so I wouldn't recommend running off," Yuma added.

Tenko stood up, running his fingers through his hair to try and scrape out most of the sand. Two shakes of his head dislodged a bit more, as well as causing some of it to fall from his clothes. By the time he'd finished, All for One hadn't started walking yet, but both Yuma and Rin had turned away, beginning the long trek back to the village.

All for One was no fool. He knew expecting a child this young to seamlessly integrate into a society with no others like him simply didn't make sense. Whatever had gotten him sent here had to be pretty horrific: until now Tartarus had strictly been a prison for adults only. A child of his age doing something worthy of getting him locked here forever felt impossible to imagine. He'd have to keep an eye on him, keep him nice and close until he learned the truth. Once that happened he could figure out what to do with it from there.

Thus, he stayed wary and tempered his expectations. When he started walking away from the beach, Tenko followed, and that was enough for now.

Tenko's parents had always told him never to follow a stranger, but his parents were dead and everyone here was a stranger. He'd lost that choice long ago.

Thus, he walked behind the three men who had found him, making sure to keep some distance between him and them. It took far longer than he would have hoped: by the time Rin pointed out the village where everyone on this island seemed to live, his legs were aching and his feet were sore. Still, he managed to walk to the furthest outskirts of the village before gratefully sitting down on a somewhat-flat rock just the right size for him.

The man in the lead began talking with one of the others. "Yuma, get everyone who isn't actively working and tell them I have an announcement to make. Have them come here, Tenko's done enough walking for today."

"Yes, sir," Yuma said, hurrying toward the nearest houses. The man who'd addressed Yuma did the same thing, leaving him alone with Rin, who kept half an eye on him but didn't seem to be worrying too much about his escape.

That didn't matter. Tenko didn't feel like escaping at the moment, didn't feel like doing much of anything at the moment, to be honest. He still needed time to figure out what his plans were, or if making them was even worth it anymore. He'd already hit rock bottom; everyone he knew was dead or gone, and now he had to pick himself back up again in a place where he knew nothing and no one. How would he find a place he could call home? How could he ever regain faith in himself after what he'd done?

How long before his magic hurt someone else?

He'd been so lost in his thoughts, he didn't notice the crowd that had gathered around him: the man he'd spoken with earlier bringing back a few dozen people while Yuma tacked on a number of his own. While Tenko avoided meeting any of their gazes the best he could, he could still tell that anyone not looking at the man who'd spoken with him earlier had their focus on him.

"Everyone, this is Tenko, our newest resident," the man said. "In case you can't tell, he's a bit… younger than the rest of us. However, that shouldn't stop you from treating him with the same respect you're expected to give everyone else here. Do I make myself clear?"

A scattered handful of people said, "Yes, sir!" Everyone else merely nodded.

"Good," came the response. "Now, return to work!"

The crowd began departing, splitting into six or seven smaller groups as each of them began returning to whatever this meeting had made them abandon, with one exception in a taller woman with flame-colored hair that fell to the middle of her back. She knelt next to him, not quite in his personal space but far closer than he would have liked.

She smiled, likely attempting to make him warm up to her a bit. It didn't work in the slightest. "Sorry to bother you, little guy, but would you mind telling me why you're here?"

"That's not your business to learn, Tsukiko," the man said. "Leave us alone. I have some questions I need to ask Tenko, and the answers are not ones you need to hear. Don't make me tell you again if you know what's good for you."

Tsukiko scampered off without another word, and Tenko tensed up once more. He still trusted the man at least a little, but that didn't stop him from being scared after what he'd just heard. What if everything about him was a lie?

As if to make that point stronger, the man knelt to make closer eye contact with him, although unlike Tsukiko, he gave him plenty of space. "As nosy as Tsukiko may be, she did still ask a question I should probably know the answer to. Why are you here, Tenko?"

Tenko paused for a long time before he answered. He didn't want to reveal the full story yet; in reality, he'd have preferred to forget it ever happened. Once someone else knew the full tale, that made it fact, albeit one that could be warped by time and distance. Thus, he phrased his response as carefully as possible, staying truthful while leaving the important parts out.

"My magic," Tenko said. "It hurts people. They wanted to send me to a place where it couldn't hurt anyone else."

While anyone could use their magic to hurt another, provided they wanted to do such a thing, someone's magic itself being inherently harmful to others just wasn't supposed to happen, or at least that was what he'd heard from the men who guarded his cell before he was sent here. If another person with magic like him existed, Tenko didn't know of them, and judging by the look on his face, even someone as learned as this man knew of no such thing.

"That is very interesting," came the response. "Do you mind demonstrating it on me? I promise I won't do anything to you afterward."

"I shouldn't," Tenko replied. "I don't want to hurt you."

"You won't hurt me, I'm too strong for that," the man said. "Whatever you can do to me, I'm sure I've been through worse."

He dropped to his knees, stretching his arm out toward Tenko in a show of submission. His face remained impossible to interpret, leaving Tenko to try and figure out whether he was being genuine or if this was just some sort of horrific test.

Tenko, terrified as he was, took the invitation, reaching out and holding the man's arm in his small hands. Then, as he'd done when he activated the Key, he closed his eyes and pushed.

He only managed to press his hands against the man's arm for a second or two, but he instantly regretted it; he could have destroyed his arm, or gotten it ripped off, or something equally bloody. However, the man seemed to have accelerated healing or something, because even as Tenko's hands destroyed the flesh of his arm, it near-instantly was replaced with new matter, seemingly without even straining the man. Less than a second after he'd stopped, the whole arm looked good as new, albeit emitting a pungent smoke from the spot where he'd gripped it.

"My, my, that was something," the man said, his smile rigid. "Now, how did you do that?"

"I don't know," Tenko said. "My magic just works that way."

"Do you know why?"

Tenko looked one more question away from starting to cry. "No one told me. They just locked me in a room, told me I was being sent away, and the next thing I knew, I was here."

The man didn't respond to that with a sentence or even another form of understandable communication. Instead, he frowned, then began leaning towards him, breaching his personal space in no time as Tenko tried to back away. He didn't get out of reach in time, though; without even asking him first, the man began resting his hand on Tenko's shoulder, although at least he didn't grab it like Tenko had done to him earlier.

"Wait," Tenko said. "What are you—"

Before he had the time to finish his sentence, the world faded away. In its place was a dreamscape of sorts, fuzzed over just enough that the fine details of it were near impossible to make out. Currently, he stood in a meadow, with several children his age alongside him as they played a game. What game, Tenko didn't know, and before he could figure it out, his surroundings morphed into something completely different.

He tried escaping, but he was locked in place. He tried changing what was being shown with both his thoughts and his voice, but nothing happened. He tried pleading with the man who'd seen fit to do this to him to stop, but he either didn't hear or didn't care.

After a large number of aimless, unpredictable scene changes, he found himself somewhere else once again. Unlike the other locations, he could see everything around him with near-perfect clarity, even if things in the distance were harder to make out than he remembered. He appeared to be in some kind of replica of his hometown alongside numerous others, the buildings just as he remembered them last. How he'd gotten there remained a mystery to him, but he felt reasonably comfortable about it remaining so.

That relative peace didn't take long to unravel, though. Upon looking up as he was led inside, he saw the sign above the door, and that's when everything began making a horrible amount of sense.

Tenko knew where he was. He knew what was coming. "No," he said out loud. "No! Please!"

But then the memory slammed into him at full force, and all he could do was brace for impact.

The Hall of Artifacts was packed to the brim, Tenko barely having enough room to stand beside his parents despite the building's immense size. While Kiri no Mura was no great city, it stood in a particularly rural area, meaning it had the only Key for a hundred miles in any direction. Anyone who wished to access their magic needed a Key to unlock its potential, meaning families with children of ages they deemed acceptable for miles and miles had crowded the place, each of them waiting their turn to use the Key. Furthermore, while some cities held this ceremony quite frequently, Kiri no Mura only did so twice a year: once on its longest day, and once on its shortest day.

All the buildup led to a great deal of energy that had stuck with him all day. He'd been awake since well before sunrise, nearly bouncing off the walls even during the relatively minimal chores he took responsibility for each morning. He'd been shooed outside shortly after breakfast to run about for a little, only returning inside to clean himself and dress for the ceremony. It felt like both a thousand years and only a few seconds passed between his waking up and his arrival, but now he gazed at his surroundings, desperately willing time to go faster.

Kiri no Mura's Hall of Artifacts was a grand building, one decorated far more richly than anywhere else Tenko knew. Stained glass windows, elegant columns holding up the roof, carvings of fantastical creatures carved into the walls, and much more made it a sight to behold. As the name implied, it was designed to hold all the relics of the past the village had collected over the years so that they could be seen or analyzed by others, although due to the event happening, all the artifacts had been stored somewhere else, save one. When Tenko arrived, he noticed the other children looking around, fascinated by the splendor.

However, none of that held Tenko's attention for nearly as long: he'd been here before. Much like the other children who'd been here before, Tenko's eyes were glued to the Key.

Despite its name, it looked nothing like a key. Instead, it was a sphere of shiny black material about a foot in diameter, calling out to everyone in the room with an alluring glow of energy. Keys were among the most valuable items in existence, for making them was a lengthy, delicate procedure, and they often proved fatal to their makers if the process deviated even slightly. Those who successfully created a Key guaranteed their names a place in the history books for centuries to come; only the most accomplished wizards in the world could even hope to try.

For some time, the room was filled with conversation. However, before long the doors were closed, leading everyone in the room to quiet down as if by magic, which wouldn't have surprised Tenko all that much. Once near-absolute silence filled the room instead, a man emerged from somewhere he couldn't see, wearing simple black clothing and announcing himself as the officiator for the ceremony. After speaking some opening words about the brilliant men and women who'd helped create their Key that Tenko only half-heartedly paid attention to, the ceremony proper began, and Tenko's heart started threatening to explode out of his chest.

Before the sun had set, he'd finally be able to use magic.

Then came the wait. The officiator had called name after name after name, none of them being ones he cared about. While he had a few others he could call friends, he didn't know any of them closely, nor even remember whether or not they were here for this ceremony. Tenko was close to the minimum age where a person could use the Key; many parents had their children wait longer, some even into adulthood. It made Tenko all the happier that his parents were not those parents.

"Tenko, of the Shimura family."

The officiator still had many names to go, but his was the only one that mattered.

His parents nudged him up toward the stand. "It's your turn, Tenko. You can do this."

"I can do this," Tenko repeated under his breath. Having just seen just shy of twenty other children repeat the process had calmed his nerves a little, but his heart still felt fluttery in his chest. Finally learning the kind of magic he'd been born with would change the course of his life forever, how could it not make him nervous?

Still, his hopes remained high. The boy before him had made the flowers nearest to him bloom several months early, while the girl before that emitted an intense heat from her hands that caused a plume of steam to erupt in front of her. While Tenko knew each person's magic was quite difficult to determine without seeing them at work, he hoped he'd at least be able to do something interesting with it.

He and his parents soon reached the front of the room, snapping him out of his thoughts. The officiator smiled at him, then turned to his parents.

"This is your last chance to withdraw consent," the officiator said. "Do you consent to your son using the Key?"

"We do," his father said, smiling wide. "We approve of him obtaining his magic."

"Very well, then," the officiator said. "Young lad, come with me."

Tenko followed a step behind the man as the two of them closed the short distance between them and The Key. The Key had been lowered to chest height for Tenko, allowing him to stumble up to it on unsteady feet with it in his line of sight the whole time.

Once he stood beside the stand, with nothing else left to do but watch, the officiator gestured forward. "Your time has come. Please, place your hands on the Key."

One last pause. Tenko relaxed, looking at his parents for any encouragement they could give him. The time had come: he had but one chance. Best not to waste it.

Tenko took a deep breath, laid his palms across the top of the Key, and pushed.

Instantly, something felt wrong. He'd heard from others that utilizing the Key would cause him to feel a gentle glow, but instead, it felt like a roaring inferno, one that nearly had him doubling over with pain. He screamed and tried to pull away, but his arms refused to obey In front of Tenko's disbelieving eyes. Within an instant, the smooth surface of the key began to warp and melt around his fingers, the sight causing the officiator's screams to join Tenko's as he raced to dislodge the precious Key from its stand before it could be ruined.

"Let go," he yelled. "Please, just—"

Then, before anyone could react, the Key exploded.

Keys required an immense amount of magic condensed into a rather small space to fulfill their purpose: it was what made them so dangerous to create. Successful Keys also received extra protective enchantments by default to make them as difficult to damage or destroy as possible, both to extend their usefulness to as long a period as possible and to prevent just this very thing from happening. Somehow, for Tenko, none of them had been enough.

In the tiny space of time where everyone knew what was happening, just about everyone in the audience let out a horrified scream.

Unfortunately for them, their screams were cut short by the explosion of pure magic coming from the now-nonexistent Key, one which merely sent Tenko sprawling before slamming into everyone else here for the ceremony. A few of the adults at the back had hastily cast whatever magic they were capable of, but it hadn't been nearly enough, the pressure wave still tearing through their bodies like a wild bear through its prey. The building suffered the same fate, stone and wood and glass flying in all directions before what skeleton of the building remained collapsed under its own weight, turning it into little more than a pile of rubble.

When the worst shaking ended, Tenko, badly bruised but having escaped major injury, staggered back to his feet. A thick cloud of dust obscured his view somewhat even once the building stopped falling apart around him, but he still had more than enough vision to see the destruction he'd just caused.

The people would be what forever found a home in his mind, though. A few of them had been turned into little more than red smears. Many of them were in pieces, chunks of meat thrown every which way in the explosion, a severed arm even lying at his feet.

All of them were unquestionably dead, and nothing he could ever do would change that.

Despite all of this, Tenko still stood near the remains of the destroyed stand where the Key had once been held, facing where the crowd used to be. Even after the explosions finally ceased, he stayed that way for a few seconds that lasted a small eternity, eyes open but brain uncomprehending. This only ended when he mercifully blacked out.

Several of the town's guards found him there a short while later, wailing amidst a sea of half-destroyed bodies and the ashes of what had once been the Hall of Artifacts, the foul stench of his smoke everywhere and everyone he'd ever loved lost to the aether. None of them said a word to him, didn't bother in the slightest trying to figure out just what had happened, instead opting to pick him up by the shoulder and whisk him off to the holding cells. They all seemed more than prepared to place the blame on him, which hurt terribly even if the incident was his fault.

As Tenko watched the remains of the wreckage he'd created disappear into the distance through his tears, the only thing that registered through his grief was that all hope was lost.

With a deep breath, All for One disentangled himself from Tenko's memories. Engaging with another person in such a way always gave him a splitting headache if he did it for too long, but the pain meant nothing compared to the utter giddiness he currently felt. His desires hadn't been this spectacularly fulfilled all his life, and he'd lived a long time.

His revelry was only interrupted by Tenko himself, still crying but just composed enough to speak once more. "What did you do to me?"

"I made sure your statement was truthful," All for One replied. "Thankfully, it was."

"But why?" In times like these, All for One had to remind himself he wasn't dealing with another adult; children had a harder time drawing logical conclusions. "I trusted you. Why don't you trust me?"

The naivete was almost endearing. Almost. "Unfortunately, Tenko, people lie. That's true of everyone, but especially here. Lying's far from the worst thing anyone here has done. And it's a good thing you're not; you're too young for that."

He thought that using Tenko's name when speaking might make him a bit more amenable to anything that was to follow. Sure, he wasn't going to get a child to jump off a cliff, but maybe it'd make Tenko a bit more likely to at least stay where he could keep an eye on him.

Right now, though, Tenko wasn't having it. "Everything you've said is bad, so why are you smiling?"

All for One decided to tell him the whole truth there; everyone else knew of his greatest ambition, so why not Tenko? "You, my boy, may very well be exactly what we need to get us all out of here."

Tenko's expression remained static. "How do I know you're not lying? Didn't you just say everyone here does that?"

It took a great deal of composure for All for One to answer that question without exploding, which thankfully he'd had plenty of time to develop. It wasn't necessarily the boy's fault, he'd asked a logical follow-up question, but if this child refused to believe he was the literal best thing that ever happened to him, he didn't know what to do from there. Thus came the truth, or at least enough of it to matter.

"I've been here since long before you are born, and without you, I will remain here until long after you are dead," All for One said. "I'm not sure whether or not this is obvious to you, but that's not how I'd prefer to spend my life if I can help it."

Tenko at least seemed to understand that. "I wouldn't want to do that either."

"Well, if you're not willing to help, that's going to be your fate, too," All for One said, trying not to look like he was relishing in the shock that formed on Tenko's face. "Once you're sent to Tartarus— that's what this place is called, by the way— you stay here until you die. However, you might very well be capable of getting out of here. And not just for yourself, but everyone else, too."

That seemed to rile Tenko up. "Wait, isn't everyone else here for a reason? They wouldn't send good people here, right?"

"Aren't you here for a reason, as well?"

A loaded question, but it worked nonetheless: Tenko held off on pressing any further about that issue, although now he looked like he was holding back tears once more. A few seconds of quivering later, he lost that battle.

All for One sat beside him, waiting for Tenko to calm down. He had all the time in the world now, a few more minutes wouldn't hurt anyone. Everything Tenko had been trying to keep inside in front of everyone else came tumbling out, and while All for One knew comforting people didn't mesh with his skill set at all, he could at least pay attention and put on a front: he'd done plenty of that in his life.

Tenko's eyes had gone red again by the time he finally ran out of tears to cry. By then, he looked as dejected as All for One had seen him since he arrived. However, that didn't stop him from asking the question All for One had been waiting for ever since he'd plumbed the depths of Tenko's memories.

"Why am I so important to this?"

As simple a question as that sounded, the answer that followed was not. It involved a concept both incredibly simple and impossibly complicated, one that had never been relevant in Tartarus at least since All for One arrived, and likely not on the mainland either. He knew enough to recognize it when he saw it, but not much more.

Still, no point in trying to hide it. The sooner Tenko knew what he was, the sooner he'd understand his importance. Thus, All for One asked a simple, powerful question.

"Have you ever learned about anti-magic?"

Don't ask me how I got here, because I'm not sure either. I had an idea to give Shigaraki a new backstory in a fantasy setting, and here we are.

This was supposed to be a very long one-shot, but I got sick of waiting to post and/or it was shaping up to be way too long to comfortably read in one sitting, so I've split it up. I'm expecting three chapters, although the other two might be longer or shorter depending on how the story pans out; however, it will be fairly open-ended no matter what, since the ending's already set up. I've also got 2,000 words of the next chapter already done, so hopefully it doesn't take long to post, but at the same time, I've never been the best with scheduling.

That said, I hope you enjoyed this chapter. Thanks for even getting this far, and I hope to see you again next chapter!