The Monster Hero

by DarkPhoenixKing

What if AFO decided to put all of his scientific knowledge into a new way to reach his goal? This is that world. Let's follow the story of the little monster who chose to be more, and see what if...

1. Meeting Experiment 7691

It was a trap. Of course it was a trap. Everything this monster has ever done has been a trap in one way or another, but today would be different. This was the day that the Emperor of Crime, All for One, would finally fall, and his master could finally rest in peace. These were the thoughts that went through Toshinori Yagi aka the Number One Hero, All Might's, mind as he clashed with his nemesis again before they were both blown apart.

Sudden the red eyed villain started to laugh, "You must be such a disappointment to Nana. She had been brilliant, powerful, and I'll admit beautiful, but you…" AFO shook his head, "A moron. A bull unable to handle his own power. You will never be a worthy successor, but…" The villain laughed again, "That's why I decided to give her one." AFO snapped and a child suddenly appeared out of thin air with a squelching sound from a glob of goo.

The kid couldn't be older than twelve with cropped black hair and the same red eyes as the man beside him, if a bit dead and lifeless. He was wearing nothing but a pair of black shorts and a collar that rested flush with his throat, showing off a horrifying amount of scars, and it nearly broke Yagi's heart. AFO reached over and rested a hand on the boy's head, "Let me introduce my… son… Experiment 7691. Say hello, my boy."

The collar sparked and glowed, making the boy scream and roar in pain until his body started to swell. What had once been an innocent, if slightly muscular kid, was now an extra foot taller with thick lizard-like scaly skin, strong digitigrade legs, a thick tail, clawed hands and feet, and bone-like spikes and spurs running down his back and surrounding his now large sharp jaws. As Yagi looked on in horror, the boy rushed him at incredible speeds and tried to rip off his head before spinning to smash him in the gut when Yagi dodged. As the Symbol of Peace, struggled to dodge and regain his senses, he saw the boys eyes full of nothing but rage and pain without the spark of self or humanity he hoped to see.

AFO just stood and watched the exchange with a smile, "That's right, my boy, tear him apart. Bring daddy his quirk."

The collar began to spark again at his words, and once more the boy let out a pained roar as his body swelled with even more muscle, causing his scars to tear open and coat him in a red mist as if his blood was burning in his veins. Seeing this was too much for Yagi. This child had to be in indescribable pain, and he had to end it. This child needed to be saved, no matter what. For the next Minute, All Might tried every trick he knew to slow the kid down but nothing worked. He simple tore his way out of the chains he tried to bind him with, and when some concrete rubble fell on him he just raged until he was free again. Finally, Yagi managed to grab hold of the kids tail, but to the heroes horror the kid just kept pulling until the skin and muscle tore and bone snapped.

What happened next was truly disturbing. Yagi threw the tail aside in disgust, but the kid chased it, and for a moment the kid seemed to calm and shrink back to his previous reptilian form… before he started eating the tail. It was grisly and bloody, but it didn't last and Yagi noticed the kid seemed to start healing rapidly as he ate. Spotting an opportunity, Yagi wrapped an arm around the kid's neck to remove the collar, and felt clawed fingers tear into his gut and savagely destroy everything he could, but Yagi succeeded in ripping off the collar causing the kids throat to bleed, but freeing him in the process.

This appeared to be something AFO hadn't planned for, and as soon as the kid saw him, he roared and charged at the white haired villain. Yagi was bleeding badly, and on his last legs, but he saw what happened next. Somehow the kid managed to get the top of AFO's head in between his fangs and bite down causing a cracking sound and a splash of blood as the villain seemed to only hold on due to grit and some kind of quirk. Regardless to say, the top of the man's head was now gone, and he looked like he only had seconds left. Blasting the kid away, AFO fell backwards into a portal, and disappeared. Whatever AFO had hit him with seemed to finally put the kid down as he lay, hopefully only unconscious, and Yagi joined him. The last thing he heard was the frantic shouting of his friend and sidekick, Nighteye, before everything faded to black.

When Yagi woke up, he felt weak, exhausted, and was covered in bandages. Everything hurt, but at least he was alive. After a short while a tall man in an immaculate suit, shiny dark green hair with three yellow triangles, and elongated features walked in with a tiny older woman with a syringe-like cane. Before Nighteye could rush over to check on his friend, Recovery Girl seemed to move faster than anyone her age and size should be able too as she smacked the injured man in the head with her cane and shouted, "ARE YOU REALLY THIS DUMB OR ARE YOU JUST SUICIDAL!"

Nighteye pulled the aged medic away, and bowed, "I'm sorry All Might. First I was late reaching you and now I can't even keep Recovery Girl from attacking you. I'm a terrible sidekick."

Yagi smiled, and tried to reassure him, but instead he coughed up some blood causing the two men to freak out until Recovery Girl assured them that Yagi was stable. The blood was just a side effect of the man's new condition. She had done all she could, but there was simply too much damage, and her quirk was healing, not regeneration. Those organs were gone for good.

That reminded Yagi about the boy, and he was assured that he was fine… heavily sedated, but fine. Yagi noticed the apprehensive queasy look Nighteye was giving him though, so he sighed, "There's more isn't there? Please tell me you at least found his family because I refuse to believe that even that monster would experiment on his own son."

That seemed to redouble Nighteye's pale nauseous look as he looked away, "We did tests to try to figure out who he is or was, but that Devil refuses to make things easy. The kid is eight, and has at least four quirks along the DNA associated with them, but tracking the original owners down is proving difficult. We-we did manage to determine his core genetics though… to an extent, and you're not going to like it."

Yagi rolled his eyes, "I don't care if that monster used some big shot or important person's DNA to play Frankenstein. Whoever it is deserves to know he's safe now."

Recovery Girl cleared her throat since Nighteye didn't seem able to tell him, "Toshi… the paternal donor isn't on file, though it did match the uncontaminated blood on his face, but his mother… appears to be Nana." Yagi froze. "I'm sorry, but-"

Yagi growled, "That's what that bastard meant! It wasn't enough to kill her! No, he had to violate her memory and spirit! This is unforgivable, but at least the kid managed to do what I couldn't. There's no way he survived this time."

Nighteye was over joyed, but Recovery Girl gave him a skeptical look, "What do you mean?"

Yagi chuckled darkly, "Not many people can literally take a bite out of crime. Kid was forced into some kind of semi-lizard or dinosaur-esque form, and it included bone crushing teeth." The duo shuddered. "He might have torn open my guts first, but he took off the top of the demon's head. Last I saw him he was seconds from death before he teleported away. We might not have a body to study, but he couldn't have survived this time."

After that, Yagi explained what he saw, and the others filled him in on what they learned, including the fact that the kid was severely stunted mentally. He couldn't speak, and they weren't sure if he'd ever be able to. In the end, though it made Recovery girl queasy, she suggested they reach out to Memory Meister. This suggestion made both of the men in the room pale, but Nighteye slowly nodded after a while, and Yagi only agreed if they gave into one condition… he had to be present for all of it.

The amount of red tape they had to cut through to get permission to go through with their plan was nearly insurmountable even with All Might throwing his considerable weight behind it and it took weeks, but it had all come down to this. Memory Meister was an androgynous figure that completely covered themselves so that nobody could determine anything identifiable about them beyond their costume. They wore brown from head to toe and their only other features were a pair of goggles and special gloves that didn't block their quirk. Despite being a pro hero, they worked exclusively with the HSC and the police in cases where victims couldn't give statements, and even then they were usually ruled inadmissible due to the intricacies of perception and memory.

The boy hadn't attacked anyone since being allowed to wake up, but he did growl to warn someone when he didn't like something. He seemed to be able to understand a number of languages, but couldn't speak any of them. He wasn't as stunted as they originally thought either. One of the doctors turned his back, and the boy managed to get ahold of his laptop. At first they were worried he would use it as a weapon or break it, but instead he started using it to write and ask questions. The grammar was a bit rough, but the boy showed an incredible intelligence far surpassing the average eight year old. The problems started when he started making requests, namely live game. They at first wanted to say no, but one of the nurses caught him hunting rats one night with the remains of his cuffs still around his wrists, and they had to give in for their own peace of mind, as grisly as it was to see.

It was late and long past visiting hours when Memory Meister, Recovery Girl, and All Might walked into the boy's small room. The staff had found him a decent bed, and an old laptop to use while he was 'under observation'. He didn't seem to mind, and he had suggested converting the small shower into the place he'd eat… the tiles and water helped clean up the blood. The boy had been informed about what they intended to do, and he'd growled his dislike for it, but after a bunch of non-insubstantial bribes in the form of four chickens, an adult boar, and half a steer he gave his permission.

When they approached, the boy was visibly on edge, but started applying the padded restraints the hospital had provided for him. As a sign of respect they didn't ever put them on him, excluding the final one, and allowed him to do it himself. Many of the staff refused to approach him unless they were three quarters applied even in his completely unquirked appearance. It annoyed the boy, but he agreed to it if it meant he could get his meals and rest. Recovery Girl handled the last restraint, and the boy gave her a tired but kind smile.

Once that was done Meister nodded and placed their hands on the boys temples from behind. From out of the goggles came projection lights that played what they saw on the wall with only a three second lag if the hero was to be believed. The boy did his best to close his eyes and relax.

It was dark and then they opened their eyes for the first time. They were floating in a vat of some kind, and they saw a man none of them could identify because his entire face seemed obscured somehow, as if someone had already gone in and intentionally blocked it from being remembered. They were forced to just float there unable to move for days as the world rapidly moved around them, but very little was detailed since the boy seemed to occasionally slip in and out of consciousness.

Then the vat began to drain, and they saw the boy take his first breaths. Before the boy was even fully aware of himself they saw the doctor attach a collar around his neck, and the world flashed red as pain washed through his perception for a moment before he simply collapsed.

The next time he awoke, the boy was in a stone room. It was completely empty with only a thin blanket, a hole in the corner, and a single camera above that focused on him. For the next week, he was left alone without food or interaction, but the boy didn't seem to notice and only focused on catching rats to eat much like had been reported by the hospital staff. After that he was led by a man in a mask to a new place. It was a round room with a sand floor and weapons lining the walls. A few seconds later a new man stepped out of the door across the way and rushed at him.

The adults recognize the man as a missing hero, Bladelock, and now that they had a frame of reference they could tell how old the boy must be given when the hero disappeared and the size comparison. The boy couldn't have been older than five, and the hero was attacking him. Bladelock's quirk had been steel skin with bladelike fingers, or Blade catcher. He had been a good man dedicated to rescuing others by tearing through rubble and acting as a shield, but now he appeared crazed and it had been this hero who gave the boy his first scar, a gash on his chest. Through the boys eyes they saw the world get hazy as the rage and pain of his wound overwhelmed him, and he became a beast until Bladelock lay dead at his feet. In return, the boy was given some bread, a new blanket, and a pair of shorts as he was returned to his stone 'home'.

The pattern continued as he was pit against kidnapped heroes, wild beasts, other teens, and begging villains. Sometimes the boy won without much of a struggle, other times he seemed pushed to his limit, but he never lost. More than once he bit into someone and tore off or ate what he got, but he was never given a choice. If he didn't fight he'd die, and not fighting hard enough earned him pain from his collar.

Never once did the boy receive affection or care. His wounds were left to mend on their own thanks to whatever kind of regeneration quirk he had. All he knew was darkness, pain, and hunger, but it didn't bother him… it was after all, all he had ever known.

Then AFO had started visiting. After years of physical and mental conditioning, the man began to whisper of a world without pain. A world where the boy could eat his fill and rest if that was what he wanted, but to get it… he had to kill All Might. At first the boy just ignored him, appearing content with his reality, but that resulted in more pain, so the boy paid attention. For three months, AFO attempted to convince the boy to choose his side, but the boy remained unmoved. He did as he was told in order to make the pain stop, but if there wasn't any pain the boy refused to move. This made Yagi snort, seeing the boy so effortlessly get under the Symbol of Evil's skin gave him a sadistic bit of pleasure… until AFO got tired of asking. The next month was only fragments and pain as the boy was beaten into obedience, but one thing grew faster, the boy's hate for the red eyed man.

That was when Meiser backed away and started trembling. They quickly signed furiously that they refused to continue, and would not be assisting any further. They had warned them that for the privacy of the victim they prevented certain memories from being seen unless absolutely necessary, but something told all of them Meister saw something that terrified them. Something so horrid they couldn't bare to show it, and this was someone who routinely worked with cases of rape and torture, so whatever it was, they didn't press. All of the adults left the now exhausted boy, and Yagi was left thinking how wrong this all was. He had to find a way to help the boy.

A week later that, the boy was studying that odd hand language the goggle lady had used when a message popped up despite the laptop being hackproof, or that's what the nurse told him

(Ratgod) An inquisitive child aren't we?

(Ratgod) Don't worry. I'm a friend. I went through something much like you did, but before I come to visit. I wanted to talk with you.

(Rage) why

(Ratgod) You deserve a chance to be more than what you were made to be. Just like me. We survived and I want to help you thrive.

(Rage) why

(Ratgod) Why not? If what I've discovered is true, you're the being I've been looking for. I won't be around forever. If you let me, I'll help you become all that you can be. I want to make the world better and less painful, but to do that I need people I can trust, and when I'm gone you can continue my work in whatever way you judge best.

(Rage) I will not be anyone's slave again.

(Ratgod) Good. Never let anyone control you again. Let me teach you what I know, and when I'm done we can fix this world as partners.

(Rage) I'll think about it. For now, I have things I want to learn. I don't want to be without a voice. Typing helps, but I need something I can use easier for once I am free.

(Ratgod) In that case, I'll send you some links to better sites for JSL, and I'll reach out to a friend. I won't tell them what I will be using it for, but they might be able to make something to help. For now, try not to study too hard. If you rush you might not learn.

With that, the figure dropped a few links and left. Some were JSL like they offered, but there was also a link to overcoming trauma, one on blending in and understanding what people consider 'normal', and one to creating your own identity including tools to help with picking a name and a few other things.

When Yagi came to visit that weekend the boy smiled at him and nodded before starting to sign, [Nice to see you again. Not sure how to sign your name. Sorry. Am I doing this correctly?]

Yagi snickered, "You actually did a great job. Just in case, you can use [Toshi] for my name. How are you doing?"

The boy sat up and reached for his restraints, but Yagi stopped him, and the boy sat straight on the bed, [I met someone on line. Didn't tell them who I was or where, like I was told, but they seemed to know me. Offered to help. Very smart. Sent me links that have helped me.] The boy looked away nervously as he continued, [I picked a name. I don't want to be Experiment 7-6-9-1. I am… Izuku. I want to be free and Izuku can mean to emerge.]

Yagi's eyes misted a bit and he stepped forward a step, "Izuku Shimora… I like it. It sounds like emerging ambition."

Izuku tilted his head, [Why that sir name?]

Yagi took another step forward, "Izuku… do you know how you were made?" The boy shook his head and looked a bit sad but also confused. Another step and a sigh, "My teacher… my master… was the closest thing I had to a mother. She found me, cared for me, and helped me become who I am today. All for One, the man who made you, he killed her." Izuku looked away guiltily, but Yagi just took another step, "Afterwards he used a piece of her… to make you. In a way, you are her son." Yagi took the final step forward and gently cupped Izuku's cheek with her mighty mit, "In a way, we both are, so… I'd like to be there for you like she was for me. What do you say? Would you like to help me honor her memory?"

Izuku looked Yagi in the eyes and smiled, [Thank you… brother.] Izuku looked around nervously, [Do you think you can help me get out? This place is nice, but it gets harder to stay in control every day.]

Yagi gave Izuku a serious look, "What do you mean, Izuku?"

Izuku contemplated for a moment before grabbing his laptop to explain better, "Yagi, I'm a fighter. All I've ever known is fighting. I need to fight. My quirks are made to fight. All of this quiet is fine and it's… nice to be able to learn about what's out there, but I can feel it." Izuku flexed his fingers and his hand flickered as it started to shift back and forth, "I'm getting restless. I need to go wild and fight soon, or I'll end up lashing out. I don't want to hurt anyone. Please brother. Help me."

Izuku hugged himself, and Yagi felt himself pull the boy closer to him, "Don't worry Izuku. I'll see what I can do, but I need you to hold out as long as you can, ok?" Izuku nodded and returned the hug.

Once Yagi was back outside he pulled aside a nurse and warned them to be careful, and the nurse he spoke to promised to keep an eye out. In the time he had been there, Izuku had made a point to be kind to the nurses who checked in on him, and though his appetites are a bit terrifying, the kid was a sweetheart. After that, he started reaching out to a few friends and contacts to help him with what needed to be done.

Over the next two weeks, Izuku started showing signs of increased aggression and instability, but thanks to Yagi's warning they were prepared and they knew it wasn't Izuku's fault. On the two month anniversary of the fight, Izuku was barely holding himself together. His hands were stuck as claws and his body was half covered in scales. In a moment of clarity, Izuku had Yagi bind him with quirk suppressants from head to toe. They wouldn't slow him down long, but hopefully it would be enough to allow them to get into position. Yagi had Izuku flanked by two other pro heroes on loan from Yuuei. One was Eraserhead, the long haired hobo looking teacher of one of Yuuei's heroics departments and a capture expert, and the other was Cementoss, a man with an appearance like a cement slab and a dedicated teacher of literature, along with the perfect quark to bind Izuku if it was needed.

Izuku was loaded into an armored truck with Eraserhead across from him so he could use his quirk, Erasure, to try to help bolster Izuku's will to hold back his quirks urges. Meanwhile, All Might sat to one side and physically held and comforted his little brother, while Cementoss carried on a debate about the literary merits and perspectives of Sun Tzu's Art of War to help him focus on remaining in control. The drive was slow, and even with Erasure's help Izuku was slowly losing the fight, but they managed to make it to Yuuei and more importantly… one of their mock cities.

As soon as they arrived, Izuku tore himself free and ran inside on all fours. Cementoss sighed at seeing it, but called his boss, "Nezu. Our guest has arrived and is already on the dance floor. I hope you found him a partner because that kid is going wild."

They all heard the sound of gunfire and creaking metal as Nezu came over the speakers, "Not to worry, Ishiyama-san. I made sure the city is fully stocked and I'm personally at the controls. There's no chance that… oh, I did not know he could do that. Well, not a problem. You three can come join me in the control room. Also, I'm recording this on a private network, so we can determine how best to help Shimura-san." There was a thunder crack and a different kind of roar followed by Nezu's chaotic laughter, "That's right! Rage! Show me what ya got! Let's see who's the real predator!"

As the laughter was cut off and the speakers fell silent, Yagi paled, "Izuku's going to be ok… right?"

Eraserhead sighed and Cementoss put a reassuring hand on the number one's shoulder, "He's never killed a student before, but he's been giddy about meeting him ever since he first talked to him."

Yagi froze, "But they've never met?! How could they have talked?"

Erasurehead groaned, "Rat Satan can and will do whatever he wants, when he wants, and there isn't a fire wall, encryption, or system that can stop him. He's the smartest mammal on the planet, and equally as crazy. Just come on. If he invited us to the control room there's probably a reason, even if it's completely illogically."

It took three hours to exhaust Izuku, but Nezu never stopped laughing and challenging the boy with robot after robot, including a few from his private stock. Throughout the time, various teachers stopped by to investigate, but they all left feeling terrified… whether it was of Izuku or Nezu varied. When Izuku was finally satisfied he started signing at the camera that had been following him and Yagi laughed.

By this point, Eraserhead had begrudgingly introduced himself as Shota Aizawa, and he turned to Yagi confused, "What's he doing?"

Nezu seemed to be coming down from his 'fit', so a passing teacher in dominatrix gear answered, "That's American Sign Language, Shota, but mine's a bit rough, I'm having a hard time following."

Yagi smiled, "He's thanking all of you for helping him, and saying he feels a lot better." Yagi scoffed, "He's also asking if you've got anything bigger to fight next time and complaining he can't feel his legs." Yagi leaned down and turned on the intercom, "Don't worry young Shimura. Recovery Girl is on her way with gummies. Then we can go talk to Lunch Rush to see if he's got anything raw and bloody he doesn't mind giving up." That got all three teachers to look at Yagi in confused disbelief, but Izuku just gave him a thumbs up before letting his arm slump.

Yagi went to go collect Izuku but found his way blocked by the dominatrix clad teacher, "Hey, All Might, firstly nice to meet you. I'm Midnight, the eighteen plus hero, and I need some answers. One, whose the kid? Second, why are you both here? Third, what's up with the bloody meat? And last… can I get an autograph?"

Yagi smiled, "In order: classified, classified, his quirk causes a predilection for it, and sure." Yagi reached into one of his pockets for a small notebook, and wrote something down before handing it to her. Looking back he gave the trio of educators a nod, "Thanks for the help Principal Nezu." And with that he was gone.

Midnight looked down and clutched her autograph to her chest like a teen before dashing off too.

Aizawa sighed, "Dammit Nemori, why do you have to be so illogical?"

Nezu smirked, "I want him."

Cementoss paled and Aizawa grumbled, "He's eight you sadist. He's too young for high school courses."

Nezu clapped his paws, "Don't care. That child is pure chaos, and I want him as my student. I'll send them an e-mail about private tutoring. From what I've seen he barely needs it, but I can't let this one escape me. He's the perfect ally for when I overthrow those corrupt bureaucrats at the Hero Safety Commission."

Aizawa sighed, "Nope. Not getting involved. Ken, you know where to find me. I'm taking a nap."

Elsewhere All Might was seen carrying an eight year old into the cafeteria, and right up to Lunch Rush. The students watched in awe as the pro looked incredibly uncomfortable, but led them to the back. When Lunch Rush returned fifteen minutes later, they looked pale and the kid was walking on his own next to All Might… with his face covered in blood. The duo didn't stop as they walked out and nobody tried to stop them.

Instead of heading back to the hospital, Yagi took Izuku to his home. In the car he left that morning, Yagi helped his little brother clean his face with one of his spare rags that he kept for his cough and deflated before they went inside. People would assume that the number one lived in a mansion in the rich part of town, but he didn't. Toshinori maintained a modest two bedroom apartment in the economy or business district as would be expected of his alter ego, Toshinori Shimura, personal assistant to the number one hero. The building was clean, well maintained, and filled to the brim with the office workers of the various agencies in the area. The perfect place to overhear rumors, while staying hidden where nobody would look. Top level security without the hassle of the press.

Stepping inside, Izuku was blown away by how nice Yagi's house was, but the hero just laughed knowing it was actually very simple and without the usual creature comforts that many enjoyed. Izuku signed, [Is this really all your Toshi? This is so comfy and warm.]

Yagi guided him over to the table as he answered, "At the moment, but I'm interested in getting a roommate." He tapped the adoption form on the table, "What do you say Izuku? What to live with me?"

Izuku froze and started to tremble. For a moment Yagi thought he had done something to hurt Izuku, but then he started to cry, rumble, and rapidly sign as he hugged the larger man, [Yes! Yes! Yes!]

Yagi returned the hug, before kneeling down and looking Izuku in the eyes, "I just want to be clear. You'll always be my little brother Izuku. This paper only means that in the eyes of the government, I'm your guardian. I know we're going to end up arguing at some point over something or other, but I promise you'll always have a home with me. I love you, Izuku. Please never forget that."

Izuku nodded and with his eyes still damp he hugged his big brother tight. They'd sign the paper later. For right now, he just needed to hug his hero.