I guess I'll do it this time.
A/N: just to reply to some reviews.

SonicMax: Nice one, actually. I like your way of thinking.

Freddielebron: I thought quite a lot about your review, ngl. For some reason though, for me it seems as if you think that Izuku decided to spread, while it was Stain that got it into his system himself. Even that aside, even if it was Izuku doing it himself, there's a reason why it happened. It won't work the same way, as it did with Izuku.

I'll give you a hint. Imagine if someone just took All Might's hair and ate it. Would the person receive One For All, if All Might never had intention to pass his quirk onto that person? I'll explore that mechanic in the future, and it is heavily tied to All For One not just as a quirk, but as a person.

All Might, or Yagi Toshinori as he asks people to call him when he is not in his muscular form, glanced at the Tokyo in late evening from a rooftop. With all the heroes and the military around, he doubted his presence will be essential.

Well, even if the city will manage without him, Toshinori won't manage without this city. He needed to help people to calm his nerves.

The outbreak, that damn outbreak is the reason why All Might barely has any rest, and why Yagi Toshinori barely has any sleep. This city, being the closest to Musutafu, now was full of desperate, bitter, angry and sad people. Their homes, their loved ones, statuses, jobs, city – some people lost a lot, and some people have nothing to lose now. The citizens of Tokyo helped as they could, giving clothes, shelters and food to the refugees, but the atmosphere in the city was more than tense. Losing such a huge amount of people was a hit not only on Toshinori's psyche, but on the reputation of heroes overall.

People won't care how dangerous the parasite was. They won't try to find those responsible for it. No, the only things they will see are the death toll, the dome that had normal people left inside when it was finished and the ones who didn't oppose it like good dogs – the heroes.

Even he was not sure if his words will reach people. The frustration of those who fled Musutafu was high, and sooner or later it will spread over the country.

Even then, he won't stop. He never cared about how he was perceived – he did everything he could to be the best hero. He will continue doing it, even if he is not appreciated. Well, he doubted that the situation was that bad when it came to heroes, but he had to be ready for it.

…Was it doubt, though? Maybe he just hoped for it to be not this bad, while ignoring the obvious signs?

Toshinori coughed a few times while going downstairs from the roof, and covered his side in pain.

His time limit has lowered significantly in the past few days. He used every hour, every minute, every second and then some, saving, saving, saving everyone he could see until he passed out. Once awake, he continued until the next time he lost consciousness somewhere.

Overusing his quirk only steeled and fastened the end of his hero career.

Which meant that he needed to find the successor soon.

Honestly, he should have done it much earlier to not be in a rush now. If he were to rush the decision, he had a chance to make a mistake, and give his quirk to an irresponsible person, that will at some point either turn to villainy or die from using it wrongly.

Once out, All Might made a sigh and started going.

In such times, every mistake is fatal. Everything had to be calculated.

He wanted to use UA as the easiest way to find the successor. But, with the destruction of the Musutafu it will be much harder now.

The school itself…survived, in a matter of speaking. They don't have resources, they don't have their own building, but the staff is alive. With the connections they have, the school will rebuild itself in time, but it was out of question the without resources they won't manage to train the current hero courses, and they had to put general courses somewhere.

If only they had Cementos working…they would restore everything within months.

Something interrupted his thoughts as he approached a crosswalk. Toshinori looked to his sides seeking the reason why he suddenly felt chills. Why he felt unsafe. As if the last few minutes didn't exist, and in reality, he barely escaped something that was hunting him. The feeling quickly disappeared, but Toshinori trusted his instincts.

Looking on the other side of the road, he noticed a boy, who kept glancing at him, and trying very hard not to.

All Might quickly noted that people around the boy were keeping their distance in half-circle. They were talking to each other, checking time, or looking in their phones – but keeping their distance from the boy subconsciously.

Once the traffic light showed green, two crowds of people started approaching each other.

Toshinori kept glancing at the boy, but without direct contact. The boy did the same…until the pair got close.

The boy with green hair stopped next to All Might and hunched, covering his belly. Seeing someone who might need help, Toshinori quickly forgot about the feeling he had before.

The blond man reached towards the boy and put his hand on his shoulder.

"Are you alright, boy?" All Might asked with honest concern.

However, his expression of care was answered with a snarl, as the boy looked at him with pure white eyes. Not a second later, black tendrils shot out of his body right in All Might's direction.

Well, whoever this boy was, he picked a wrong target. As he pounced on Toshinori, the man quickly got into his muscular form and in the next instance both of them disappeared before anyone in the crowd could process what just happened.

All Might stood on the same roof he left a few minutes ago and crossed his arms.

"That's not the way you thank people who want to help you, young boy!"

The green haired boy quickly stood up after being thrown, growling without responding.

"Hey, can you hear me?"

The boy turned his hands into some kind of claws and started running towards All Might.

'He doesn't answer. Bad sign.'

"Hey, I'm talking to you right now!" All Might shouted, dodging every swing with ease. The boy's aim was a bit off, but he was relentless and quite fast.

He continued growling and almost yelling at every swing. Sometimes, when he swung too hard, the tendrils would shoot from his back, trying to reach All Might.

Being extra careful, All Might punched the boy, being sure not to make him fall of the roof.

The boy's flying distance was less than half of what All Might expected, and it looked like he didn't even felt the damage.

A few tendrils in form of a twisted rope shot out of his body and impaled themselves into the floor, making the boy not only stop flying towards the end of the roof, but use what momentum he had left to spin and boost himself in All Might's direction.

"Ho, you are much heavier and sturdier than you look!" All Might commented, preparing another punch – just a little bit less careful one.

The boy leapt at him, but the speed, if impressive for someone his age, was not that big for All Might. The enraged boy didn't manage to do anything as he was sent flying into a wall, right next to a door that led to the stairs.

All Might widened his eyes as he noticed large splashes of something black on the walls, no doubt from boy's damaged back, while the boy himself didn't move.

'Oh no, did I overdo it?!'

His question was answered as the splashes of what almost looked like black blood quickly returned to the boy, and the empty eyes stared at him once more.

'So that's how it is' All Might sighed as the boy stood up.

The quirk was much more than simple claws, tendrils and enhanced strength. In a sense, it reminded Toshinori about the sludge villain he caught on the day of the outbreak. The man didn't have any solid body, and physical damage mostly didn't work on him. All Might was an exception because he actually uses pressured air much more than people think. The boy obviously was not even close to that villain, considering that he can make blades and-

All Might dodged a strike.

"Sorry, couldn't you sit a bit more there? I'm thinking about what to do with you!"

The boy was leaning dangerously low. The absence of pupils in his eyes made it look as if the boy was staring ahead, but All Might knew that boy's raging focus was solely on him.

There were countless more tendrils on his back, and now all of them had a blade similar to those the boy had on his arms.

The boy leaped in the air and swiped, but All Might dodged the attack with ease. In the next moment the boy spun in the air, and all the bladed tentacles on his back acted more like a grater that would shred anything they had a contact with.

All Might continued to dodge with a sigh, now wasting more attention on dodging countless bladed tentacles than on thinking about what to do with the boy.

Where was he? Ah! The boy's body most likely didn't have a one particular condition. It could act like a liquid, considering what All Might saw with the black splashes, it can be rather soft like normal person's with no skin related quirk, considering what he felt with those two punches…and it could be damn hard when he needed to create those blades. They weren't just sharp - they were quite sturdy as well.

Well…that simplified things a bit – he couldn't overdo things unless he specifically wanted to. Hopefully, the boy was different from that sludge villain when it comes to one thing in particular.

The boy is not thinking clearly, and considering that his quirk has changed his body so much there could be a bunch of different reasons for it. But he was not a villain, he was a victim. A victim of his own powers. He was not the first with such problem, and he won't be the last.

'I hope it works. Don't worry, I'll help you! Well…if you are not a villain, after all!'

The boy leaped on him again, but before he could do anything All Might punched him into the floor much harder than before.

The boy impacted the floor face first, but the tendrils on his body continued to attack blindly, protecting him. Two more tendrils shot out of his shoulders to instantly rise him on his two legs.

Now, with the defense on boy's back mostly useless, All Might punched him again, just a bit stronger.

As the boy was flying, tendrils out of his body again. Using them as an anchor point, the boy starter a spin just like the first time. All Might prepared for the boy to leap towards him again, but the boy used some kind of thick rope with a bladed end instead. It elongated with Izuku's momentum. Not expecting the attack to be this fast from such a distance, All Might blocked it instead of dodging.

The impact echoed in the air, and All Might waved his hand in pain.

"Damn, that one actually hurt a bit! I don't even remember the last time someone used anything reminding a whip on me! Ha!"

'This is taking too long' All Might added, his smile slowly disappearing, but then he blinked, while staring at his opponent.

The boy looked confused as he was stared at his arms, and then on All Might. He grabbed his head, not even noticing how his claws were scratching it, continuing to growl and whine.

All Might, once more, prayed that the boy and the sludge villain were different in one thing.

He prayed that he could at least knock him out.

"I'm sorry, boy. But I will help you, even if it will hurt a little!"

He doubted that a little of physical pain will compare to the pain of that boy he saved during the first hours of outbreak, but it still was an unpleasant experience by itself.

"Missouri Smash!"

One day later.

Izuku stopped doing push-ups.

"And then what?"

Naomasa shrugged his shoulders.

"Nothing. He knocked you out"

"Just like that? He said something about me giving him quite some time." Izuku asked, interrupting his push-ups once again. He couldn't really do anything else in his cell anyway. "And it feels like you stopped in a middle of the story"

Naomasa sighed. It was getting late, and he will be going to the hotel quite soon. Still, he visited Izuku to notify him that the samples of his… whatever it was were sent to a medical facility to check. It works in most cases. While visiting he decided to tell Izuku about his fight with All Might, leaving out Toshinori's weaker form, of course.

"Well, that's All Might to you. Most of his fights are finished before the enemy even realizes he is in one. Compared to most, you actually held quite nicely."

'And yet, I don't remember anything of it' Izuku added with some frustration. 'At least no one was injured.'

Still, there was this strange moment.

Izuku remembered when his instincts wanted him to absorb the blond man on the road. They were so strong that Izuku couldn't even think about anything else. Before that, it only happened in the dome, when he was next to weak, damaged, beaten or dead carriers.

What was so similar between them and the blond man on the crossroad? Why only they and All Might were getting such a reaction from him?

He felt like the answer was somewhere within his grasp, he just needed to reach to them a little bit harder.

'I don't attack randomly, I'm sure of it. I didn't have anything like that during those four days I've spent in the military base.'

Blond man. All Might. Their fight. There has to be…

Huh.

Izuku blinked and stopped doing push-ups again.

'If I was attacking him…why did I stop? I stopped to look at my hands, and then at All Might. I didn't attack him after that moment. But I did target and focused solely on him when I was fighting, which is wrong! I focused on the man! I shouldn't have continued to fight, right? When I was killing carriers, I didn't have any desire to attack Izumi-san!'

Izuku concentrated again, with more details.

The blond man. He looked a little sick. But Izuku doesn't attack people simply because they look sick – once again, he saw such people in the military base. But even then, Izuku attacked.

All Might. He was WAY too fast to react, he managed to both save the blond man and get Izuku on the roof. Izuku was having doubts about it even before. Now, however…

Where would he take the blond man to save him? Why didn't he just leave him on the street, where he would be safe?

…

'Hm…'

"Something on your mind, Midoriya-kun?"

Izuku looked at Naomasa, who was sitting next to the door. This time, however, there was no All Might behind it. Izuku knew for sure because he couldn't feel… his…Heartbeat!

Izuku widened his eyes.

"Y-yeah…"

"What is it?"

Izuku didn't answer.

All Might's big heart. It was strong and big, but there clearly was something wrong with it. It didn't work properly.

Blond sick man. All Might was blond, and there were some similarities in their hair. He had something wrong with the way his heart was beating.

Izuku attacked blond man, but All Might saved him in the same moment. Izuku didn't stop attacking and fought All Might, even though he should have stopped and returned to senses once the source of his reaction dissapeared. Then, while fighting All Might and it was obvious that Izuku couldn't win, he stopped attacking because of some form of confusion.

And now the instincts were acting up when All Might was close. Just in the different way.

The conclusion was obvious.

All Might and the sick blond man were one person! Izuku attacked the weakened and sick man, but once the man revealed to be more than capable of killing Izuku, his instincts went from "Absorb" to "Run and survive". It still left him with a question of why he and the carriers made him have such a violent reaction. When it came to them, his body was reacting in a way he could barely control.

"Midoriya-kun?"

'I need to get away from this topic. It's obvious he didn't tell me this for a reason!'

"Huh? Ah, sorry, I…I'm just not sure what to do here. Can't help but space out thinking" Izuku replied in rush.

"Well…I can see that, considering you were doing those pushups for an hour already"

"Huh? Ah, no, no, sorry. I meant about…school. I-I understand the reason why I'm kept here, but at the same time I kind of don't want to skip school. If I want to become a hero, I need the best grades. If I-I skip some lessons now, I might not catch up with the rest of the class."

Naomasa nodded in thoughts.

"Well…just work a little harder in the first few weeks. I don't think it will be much of a problem."

'That's the case if I even remember what we were studying this year! Or any other years!' Izuku mentally added with a bit of fear.

Skipping a week at school is one thing. Re-learning a few years is a whole different challenge.

"Though, about your push-ups…" Naomasa started with a hand at his chin.

"Hm?.." Izuku blinked a few times, not sure where this is going.

"If you don't feel tired from doing it for an hour, then I would advise you to stop. They won't help you with training, since it's obvious it takes too little effort to you."

"Wait, really?"

"Of course! For example, All Might had to train with trains. No pun intended. You have to choose your weights and excersices accordingly."

"Trains?..That's a bit too much for me."

"Well, you are you, and All Might is All Might."

"Cars would work, though…"

Naomasa blinked, before chuckling. He couldn't expect anything less from this boy, it seemed.

"It's me" Toshinori greeted over a phone. "Do you have anything on the material I brought to you?"

"Hello to you too, Toshinori." Said a voice of Recovery Girl on the other end.

UA staff that fled from Musutafu continued to work despite all odds, at least while the UA itself did not function. Recovery Girl, for a time, decided to stay in Tokyo to work with refugees.

"Sorry. Hello. Do you have anything on the material I brought to you?"

"After such rude greeting I should consider hanging up, but I'll let it slide this time. Tsk. You younger generation can't treat elders with respect they deserve. Honestly, if I were to act like you in my time-"

"Recovery Girl, please. This is important to me."

"As if it could be otherwise with you, Toshinori. Fine. Whatever the hell you brought to me, it wasn't a blood sample."

"Well, I figured this much myself. He reminded me of that Sludge Villain a bit, so I thought that his quirk changed his body quite a lot."

"And since when your eyes have microscopes to prove it? Anyway, ignoring the fact that this is the first time I see cells this small and so dense, the only interesting thing I noted was the reaction it had on your blood sample. Nothing else stood out this strong, considering the range of quirks I saw during my work."

"What happened?" All Might started to tap his foot a little, listening to the elder.

"I've yet to make most of my simulations and tests, so I started with the reaction the boy had on you. It slowly, almost lazily absorbed most of the organic materials I tested it with, either to replenish energy or to become slightly bigger and denser. But your blood sample was different."

"So what happened?"

"Stop it, boy. I'm getting to the point. Well, they began to fight."

"Come again?"

"You heard me. It was one of most bizarre things I've ever seen. Once a drop of your blood landed on the glass, the blackness sprung into action to attack. The cells in your blood started to fight back in ways I never saw before. It almost looked like they viewed each other as an infection they had to erase. Well, your blood held quite strongly, but failed since it was not designed to fight such an opponent. Then, I tried to check reactions your blood would have on different materials, just in case you too have much more weirdness than I thought before. Well, nothing strange happened."

"But It reacted to the boy's samples?"

"Did you listen to me or what? Listen, Toshinori, whoever you found, be careful with him. It's not just his reaction on you, but also yours. To me, you two are the best definition of natural enemies"

All Might looked at his hand and clenched it into his fist.

"I fought the boy. I don't remember anything similar to this happening. At least, not on his scale."

"Well, there's not much I can tell you about it. Maybe it is because of how much control you have over your power. Maybe you didn't notice it. I don't know."

All Might sighed and pinched the bridge of his nose. He never expected to have a problem so deep that he barely had any control of it. No, it was more like he didn't know whether he had a control or not.

What was there so different from other people? It couldn't be some kind of unique immune system. It couldn't be a blood type – Recovery Girl would tell him if that was the case.

So…was it related to the quirk, after all? That sounded a bit anti-climactic. The only natural enemy of One For All is All For One – the quirk of his arch-enemy, the strongest villain.

That he could understand.

But… a random boy on the street with a natural enemy of his quirk? Why? How? What are the odds of that even happening? All Might, for a moment, considered that the elderly woman is becoming too old for such work.

"So, if the boy only has a reaction on me, he can be released, right? He himself stated that he never had such reactions before."

"Honestly, whatever he says doesn't bother me at all. He could have said anything to evade time in jail. But from what I saw he is mostly normal – at least, nothing quirks couldn't do - and only reacts on you in such way. Still, better keep someone monitoring him. You are the Number One hero, surely you have resources to do that. "

She hung up right after those words, forcing Toshinori to sigh.

Finally some good news, even if it had a grain of salt with it.

Was there really something so deep inside him that was controlling him, without All Might ever noticing?

He remembered the way people were standing around Midoriya-kun in half-circle, not even realizing how they were keeping their distance. He remembered how he punched the boy into the wall, even though he tried to punch just a little bit harder. Are those the same things that Izuku was going through, just on a much lesser scale?

Now, he needed to tell Midoriya-kun the news and try to get him into one of the middle schools closer to a hero school. Luckily, he knew who to call.

Midoriya, after all, was not the first one All Might tried to help this much personally.

Though, in Bakugou Katsuki's case, the boy didn't appreciate his help much.

A soldier opened his eyes and found himself in his bed. Rubbing the sleep out of his eyes, he stretched a bit.

It hurts.

He looked at his wife still sleeping, and a small smile appeared on his face.

The Saturday mornings were the best, after all.

Wait.

Saturday?

He clearly remembered it to be Wednesday yesterday. He celebrated his comrade's birthday and…

His vision flickered, and for a moment, the sweet scent of rot filled his nose.

He couldn't be here. What Saturday? What home? He was on a mission! There was outbreak in Musutafu city! He was assigned for a scouting mission!

"Where am I?!" He shouted, with panic in his eyes. His surroundings didn't react to his outburst.

" Y̶͖͑̌ö̷̼̩̼́́͂u̴̯̥͇͛ are hom̴̢̨͕͖͙̘̖̟̼͈̯͊̈́͆̓̌̅͌̀͌̎̂̀͝͝e̷̻̤̙͎̳͗͆̄̔̂̅͛͋̈́̾ "

His own voice replied him in his head.

It hurts.

No, no, no, there's something wrong. The man pinched himself hard. There was a mission. It was terribly wrong! Everyone died and-!

"Shhh… ḭ̸́t̸͓̅'̸͓̍ş̶͐ ̸̛̖o̶̤͝k̶̩͘a̵͈̍y̵͓͑. You ar̸͗͆ͅë̴͉ home. Ė̵͓̒̐v̸̠̞͈̐͗ḛ̶̆̋r̶͔̱̍̏͛ÿ̸͓͚́͊t̷͓͂ĥ̶͖̗̗̇i̸̦͕͋̊ň̸͚͉̿̒g̵͎̙̯̐͠ is fine"

Something was probing in his head, and the man resisted it.

"Get out of my head!"

The probing continued.

There's no your head now

Grave deep voice replied.

God, it hurts so much.

You are mine

Your body

The man's hands started to move against his will, and were rised to his eye level.

Your quirk

The hands ignited themselves, even though the soldier did not try to activate his quirk.

Your memories

Images started to flash in front of the man, on a speed what looked to be close to the speed of light.

"AAAAAAAARRGH!" The man concentrated every bit of his will. "GET OUT OF MY HEAD"

A moment of silence passed, as the offender considered the request.

Hehehe…If that is your wish.

The man stood with wide eyes and panting heavily in panic.

Until…

He opened his eyes for real.

"AAAAAAAARGH FUCK!"

The pain was so strong that he couldn't think. His vision went white. For a solid few minutes, the man couldn't do anything but shout in pain as every bone, it seemed, was broken and wanted to remind him about it. With shaky breaths, the man noted that he was covered in some red goo, just like the rest of the place where he found himself. He couldn't move, but he could turn his head a bit.

"Eh…?!"

A short glance to his right showed him his arm. Instead of a normal one, it was broken and replaced with something with claws. He felt how this huge chunk of red meat was connected to him, but just like the rest of his body it was glued by the red mass of something. The man tried to use his quirk, but nothing worked.

As I said, you are mine.

There, take a look.

The man's head turned to his left against his will. At first, the man in shock couldn't understand anything but then…he saw it. He saw his friends inside that red goo, with expression of horror frozen on their faces.

Don't struggle, and you won't feel any pain.

Just like them.

"Ha…ha…hahahahahahahaAAAA̴̳͝A̶͇͗͛A̷͕̔̅Ř̷͕̤̏G̸̜͇͒̀H̴̢͉̉H̶̭̤̊̕A̸̛͓̠͌̄̽͗̿̎͗̉̄̕͝A̶̛̠͐̀̎͐̄́̂͝Ả̷͙̬̘̺̜̭̞͋͒́͒̃̈́͌͊͒R̵̥̗͕̫͑̓̑̽̃͑̈́̋̈́̂̚̚͘͠͝G̴̨̻̣̝̒̉̆͝Ḩ̶̗̖̤̠̩̟͉͎̙̩͔̞̬͑́̉̒̊̏͜͠ͅḨ̷̡̧̫̥̜̰̮̮͕͗̅́̊͌̐͋̂̏̉ͅͅ ▅▅▅▅▅▅▅!"