Archive of Our Own

Chapter Text

• • • • •

Saitama was not a remarkable person.

In fact, Genos would go as far as to say he was completely and utterly unremarkable. He was the type of person one could bump into ten times on the same day, and still end up not recognizing him.

Under any other circumstance, Genos would've probably forgotten his face the moment they parted.

But he most certainly would never forget that punch.

Well, actually, it was more of a slap rather than a punch, but that didn't matter. At that moment, Genos felt as though his already unhinged jaw just might literally drop to the floor - no words could express his immeasurable awe at the power the man possessed. He fought the mosquito lady monster for a good hour, and he would've self-destructed and died right there and then if it wasn't for-

No, his decision was most definitive. He wasn't wrong for acting on his impulse - becoming Saitama's disciple might be the best thing that has happened to him since meeting Doctor Kuseno.

The aforementioned man was now humming a lively tune while making minor repairs on Genos's new arm. The cyborg quietly thought over his encounter after having talked the Doctor's ears off about his fight with the Mosquito girl and Saitama's strength for the past 2 days.

"Becoming someone's disciple is a lot of responsibility, Genos,"- the old man told him after the cyborg was finally done with his endless monologue, -"It takes a lot of devotion to a person to declare them your Master. Think carefully about it - is this Saitama fellow really worth your loyalty?"

And so Genos had thought it over, remembering with vivid clarity every second since the moment he laid his eyes on Saitama. The way he determinedly ran after a mosquito, the way he had turned up naked yet completely unharmed after a fire storm Genos caused, the way he called Genos amazing and thanked him for saving his life and made that pun that completely went over Genos's head since he was way too busy recovering from shock that Saitama survived his attack...

And then that one punch. The one that sent the Mosquito girl's blood spraying all over a building, her remains scattering the ground. The way he just shrugged, made another joke, and began to walk away as if nothing happened.

Genos might be young and inexperienced, but he recognized greatness when he saw it.

And in that moment, he realized that Saitama was truly great.

He would normally never be this brash, asking to be a disciple under a person he barely even knew. It was completely a spur of the moment thing, but...

He sought absolute destructive power, the power to obliterate anyone and anything standing in his way - the kind his newly found Master seemed to possess. If nothing else, Genos needed to know the secret to his strength.

"I am going to visit him,"- he suddenly said, standing up with determination.

Doctor Kuseno, who had just been screwing in the last few bolts on Genos's new arm, raised an eyebrow at the sudden outburst, -"Are you sure, Genos?'

When the cyborg nodded, he had to rephrase the question, -"Are you sure he isn't just a fraud?"

Genos furrowed his eyebrows. No, he wasn't. 

He stared at the floor for a few moments, deep in thought. If only there was a way to prove Sensei wasn't a fraud... If only there was a way to find out the secret to his power...

"Doctor Kuseno,"- he finally said, turning to the old man, -"I will need to borrow a telescope from your lab."

• • • • •

Saitama had a dream.

In that dream, he killed a giant insect, and a weird looking toaster asked him if he could be his disciple. The toaster, it so happens, had a blond wig on. Out of the kindness of his heart (and definitely not out of the fact that he wasn't really listening) Saitama agreed.

Upon waking up, he also realized that it wasn't really a dream.

Although it has been a week, Saitama still was thinking about that random blond robot guy (he forgot his name already. Did he even say his name?). Recalling the events of the day for the hundredth time, he couldn't believe that he had so easily agreed on having somebody for a disciple.

Saitama swatted a mosquito lady monster out of the air (she was buzzing so much, it was becoming annoying), and was about to head home when the robot guy called him and asked his name. He then immediately asked to become his disciple - Saitama in all honesty thought it was come kind of a lame joke. So, naturally, he said yes.

Weirdly enough, the robot dude wasn't joking. "I wish to become stronger", "I wish to posses the same kind of power as you", and blah blah blah. He was quite the talkative guy, especially considering he was lying on the ground, sparking and twitching, practically dismantled.

Saitama didn't really know what to do. He was just standing there, naked, and this dude was blabbing on about how Saitama's punch was the most incredible thing he's ever seen. The situation was... awkward.

"Uh, dude,"- Saitama began, wanting nothing more than just to go home and take a bath, -"Don't you, like, need help?"

The robot guy looked himself over and said something about sending a signal and help being on the way. (It's not that Saitama didn't actually listen to what he was saying, he just couldn't remember it anymore). The moment the robot fell silent Saitama quickly excused himself, giving him his address, and then he all but ran away before the guy began another rant.

Only upon arriving home did he realize that maybe giving out his address to random people was not the best idea.

For the entirety of the next day Saitama was agitated, expecting him to show up at any moment. But now that a week has passed, he was starting to get hopeful, thinking that maybe he forgot or it really was all just a big joke.


Saitama remembered the resolve he saw in the robot's eyes (well, eye - the other was pretty much destroyed) and felt his chest clench a bit at that. For some reason, he didn't want it to be a joke. But then again, what other reason could somebody have to want to be his disciple?

Still, it was nice to think that maybe somebody out there appreciated his efforts... 

Whatever.

He realized that he's been staring at the ceiling, unmoving, for the last 15 minutes, and quickly snapped out of it to proceed with his morning rituals.

Upon opening his fridge, he found that it was quite empty. Well damn. And they just reported a sighting of a monster near the supermarket.

Saitama sighed, reluctantly put on his suit, grabbed some money, and headed straight out the door.

An hour and a half later, he was back home with a bag full of groceries and the blood of a defeated monster staining the tips of his boots. He was about to pull off his gloves when suddenly he heard a voice he instantly recognized. 

"Sensei!"

Oh. Damn. Crap.

And Saitama even allowed himself the benefit of completely forgetting about the guy. He made his way to the door in seconds, slowly opening it, hoping that maybe he misheard, or -

Nope, there he was. The blond robot guy had the most determined expression Saitama seen anyone wear and he couldn't help but make a disdained face.

"You really showed up,"- he said, maybe a tad too spiteful. The guy didn't really seem to notice, -"Uh..."

"It's Genos, Saitama-sensei,"- the robot helped, but Saitama didn't really pay attention to the first part of the sentence. He was more focused on the "Saitama-sensei" bit and how annoying it sounded.

"Could you not call me sensei?"

"Master!"

Oh god, that was even worse.

"Not master either!"

There was no getting rid of this guy, huh... Well, he did go all this way to meet up with Saitama so it would be rude just to send him away.

Why me, Saitama mentally sighed and proceeded to fully open the door.

"Just... come on in. I'll make us tea."

Genos (that was his name, right?) immediately followed. He looked way too serious, like a soldier taking an order from his commander. Saitama sighed again, making his way into the kitchen.

Putting the kettle on the stove, he glanced back to see Genos subtly (not really) looking around the apartment, taking in his surroundings. Probably analyzing stuff with his robot vision or something. Finally, he settled down at the table, patiently waiting for Saitama to get back.

As soon as the kettle boiled, Saitama quickly poured both of them a cup of tea and joined the robot.

"Go on home after your drink,"- he began. Better set things straight from the start with this guy, -"I'm not looking for disciples."

And then (only then? really?) he noticed that the guy was fully repaired.

"Wait- you're back in one piece?"

"Yes, my body is mostly mechanical. As long as there are parts repairs are quick."

Eh, that's understandable. But still... what was that part about being "mostly" mechanical supposed to mean?

"You're an odd one,"- Saitama couldn't help but say.

"What kind of parts do you use, Sensei?"

"Don't use any,"- Saitama immediately answered. He wasn't a robot, if that's what the guy was implying.

Genos now looked genuinely surprised to hear that Saitama didn't use any parts - and a bit disappointed too? Maybe it was just his imagination.

"Then what about the skin-colored armor on your head?"

Wha-

"Yeah, that's my skin."

Saitama was confused. Genos looked confused too. And then-

"But that would mean you're bald despite being so young-!"

"So I'm bald-- What's your problem!?"

He hated discussing his hair (or rather, the lack of it). Why must this guy be so annoying!? He was here only a couple of minutes and already made him-

"Me? You'll listen to my problem?"

Saitama suddenly regretted every decision in his life that led up to this moment. That was most definitely not what he meant when he asked the question.

"No thanks, I'm good,"- he told the guy, but somehow he already knew it would be useless.

"Actually, four years ago, when I was 15, I was still a real human being,"- and so it began.

"Did you hear what I just said?"- Saitama tried again, but with less resolve now. First, he knew his words fell on deaf ears, and second...

Genos was- a real human being?

Saitama decided to listen. It was the least he could do - after all, he did kinda give the guy the heads up to become his disciple.

And his life story was... well, tough. Heartbreaking, perhaps. He really did feel bad for the guy, even though they just met.

"I see-"- Saitama began when he was sure Genos had nothing more to say but then-

"It's been four years since that day."

He went on.

That was beyond Saitama's limits. He moved his leg up and down impatiently, hoping the guy would get an idea, but no, he kept going on and on and on and- he was practically saying the same thing over and over in different words, wasn't he?

This was a huge waste of time.

5 minutes into the monologue Saitama completely lost it.

"Enough, you idiot! Shorten it to twenty words or less!"- he yelled at the top of his lungs.

Yeah, sure, his story was sad and all, and Saitama felt like a dick for yelling, but this much explanation really wasn't required.

Genos flinched a little, but his expression never changed. Saitama momentarily wondered if his face was capable of showing any other emotion other than intense concentration.

"Sensei, here's the short version,"- Genos began again, once Saitama settled back down, -"Please teach me the way to become strong like you."

That sounded... rough. Almost like Genos practiced it over and over in his head before actually saying it (and perhaps he did). But it was genuine and Saitama knew the guy was being serious.

"Genos..."

"Yes!"- he jumped up slightly, attention focused on Saitama only. He was really eager for this, wasn't he...

"How old are you?"

"19."

"So young..."- 6 years younger than Saitama himself. And he already went through so much... His heart went out to the guy, really, -"I'm sure you'll surpass me in no time."

"Do you mean that?"

Did he? Saitama himself didn't quite know if it was possible. Maybe.

Maybe not.

Instead of answering the question, he continued, -"I'm 25 now, but I was 22 when I started training in the summer."

Genos looked surprised again. No, impressed. Was it really that impressive?

"Sure, I'll teach you. But it won't be easy. Can you handle it?"

"Yes!"

And that was that, he supposed. Now he has a disciple. A robot- no, wait, a cyborg disciple. Well then.

This was... going to be different from what he was used to. His entire routine, hell, his entire life was probably going to change.

Saitama just hoped it wouldn't be for the worse.

• • • • •

After 4 and a half days of spying - or, uh, observing Sensei, Genos realized how futile his mission was. He would never, ever learn the secret to his power like that.

He found Saitama's address easily enough, and set up a camp to observe his training and routine. He kinda half-expected (more like half-hoped) it would be a secret military base, or maybe a giant research complex. But it was the most regular apartment building Genos has ever seen.

Hm... But, of course! It was genius. The perfect disguise for a man of Saitama's caliber! No one would ever suspect somebody as great as him lived in a place like this!

He thought he'd observe miracles but instead... Well, Saitama proved to be just as unremarkable as Genos had previously thought. This was beginning to feel weird, and he felt more like a stalker than an observer. There must be others ways of finding out the secret to his strength -

Plus, he was his disciple. He had to face Saitama sooner or later. 

It took Genos a while to master up the courage to call out to his Sensei. When the man answered seconds later, he felt like he could take on the entire world.

Now that he was inside, having told Sensei his entire life story, he felt like self-destructing right there and then.

It was embarrassing.

Really, Genos didn't plan on talking for so long. He didn't plan on telling Saitama everything.

He had one thing to say and one thing only - Please teach me the way to become strong like you.

He rehearsed it a thousand times on the way over. It shouldn't have been this difficult to say it from the start.

But somehow, when the man asked him "What's your problem?" he couldn't help but reveal all his life. At that moment, he was overridden with all kinds of emotions. Not like he wanted Sensei to feel bad for him, no- on the contrary, Genos wanted to show him the reason behind his seeking of power. He desperately wanted Sensei to understand him but...

When Sensei yelled at him, Genos's (metaphorical) heart stopped for a moment.

He did overstep his boundaries, but Sensei was kind enough to listen. He truly was a great man...

And sure, it was disappointing to find out that he wasn't a cyborg, but then the fact that Sensei was just a human made it all the more exciting. Genos was ready to face anything and everything Sensei had to throw at him -

- and his first trial seemed to be on its way right now.

"Object approaching at high speed - it's here!"

Just as he said it, a monstrous mantis-like monster burst into the apartment, screaming and flailing. Immediately, Genos got ready to attack when-

"Pay for my ceiling!"- when it was over. Sensei knocked the monster's head off in a single punch.

Wow.

So that was his true power. Incredible. Sensei wasn't a fraud after all.

But-

"There are two more outside,"- now he could truly prove his worth to his master! -"Sensei, leave them to me!"

Genos leaped out the newly formed hole in the wall and onto the street. Yes, now Sensei will acknowledge-

"Oh, never mind."

Sensei was already done with them. Truly incredible...

"Can't you guys just come through the door?"- Saitama looked annoyed... And then, just like that, he was underground.

"S-Sensei!"

What the hell was happening? Genos rushed to help, but Saitama assured him he was fine.

"I kinda feel like a... bamboo shot."

Was this... was this Sensei's immense wisdom?

Amazing. Sensei was amazing.

A loud thud from behind got his attention, and then Genos saw him.

A cyborg.

Could it be..?

Genos was fighting before he knew it, his mind racing with thoughts. Was he the one? If he wasn't, he must know about the one he's searching for.

"I have a few questions for you."

He felt his concentration reach its maximum level. There was no way he was losing this fight - it was impossible! Nothing could stop him now.

Genos got ready to deliver another blow, when suddenly-

"It complicates things if they put up a fight."

His attention shifted. The cyborg didn't matter anymore and all that was in his head was the image of his master stuck underground, unable to fight the two other monsters that suddenly appeared.

"Sensei!"- Genos turned away from his opponent - number one mistake in any fight. He knew it, and yet he still couldn't help it.

"You dare look away? Quite courageous!"

The cyborg attacked almost immediately. There was nothing courageous about that. He was being foolish. He knew Saitama could take care of himself, and yet, subconsciously, he couldn't help but worry.

He just acquired a master, he couldn't lose him already!

"I must destroy you!"- the Armored Gorilla roared, and Genos took another quick glance at his Sensei.

He had to end this fight quick.

• • • • •

It was easy enough dealing with those stray animals. One tried to get away, but Saitama couldn't possibly let him. What if he brought along more of them? They'd destroy his apartment completely.

They didn't even apologize for ruining his ceiling. How rude.

"Oh,"- he lost Genos. Hm.

Saitama looked around at the destruction. Following the path of burned down trees and smashed buildings he found his disciple, standing over a half-destroyed robot-gorilla monster.

He was saying something about a lion fighter...

"Is this who you mean?"- Saitama held up the lion's eye that got stuck to the end of his boot.

"Apparently so,"- Genos answered, and the gorilla's demeanor immediately changed. He was way more compliant now.

Good for him.

He went on about telling a story about a scientist... what was up with those long-ass backstories stories these day? Saitama had no time for this...

"This is taking too long!"

"...Huh?"

"What's this got to do with me? You're just trying to act cool again. Just get to the point, okay?

"My Sensei is a busy man. Summarize it in 20 words or less,"- Genos said, intimidatingly staring down the gorilla.

G-Genos, you're not the one to talk like that, - Saitama thought, bead of sweat forming on his forehead.

Still, it was kinda helpful. The kid was learning quick. Maybe he wouldn't be such a nuisance after all.

"So, in other words, my boss has become very curious about your body."

Wha- Gross.

"I'm not interested in dudes,"- Saitama answered, a little unsettled about the whole situation.

He wasn't lying - he didn't swing that way. And he didn't really swing the other way either. In all honesty, he just didn't swing. He was more of a static pole, just kinda standing there, with no reason or purpose.

When was the last time he had a crush on someone-?

"I think you misunderstood, Sensei,"- Genos was quick to explain, -"He plans to use your body, which surpasses normal human limitations, for his research on evolution."

Oh. That was less gross.

Actually, wait, no. It was as disgusting and Saitama would take no part in it.

"Our move should be to attack him,"- Genos said with conviction and Saitama fully agreed.

"Sure, let's go,"- he turned to move.

He was not missing tomorrow's huge sale at the supermarket because of this.

• • • • •

"I didn't think we'd be running the whole way,"- Genos said, but he didn't sound annoyed. More like he's just making an observation.

"How else are we gonna get there?"- Saitama asks him in return. Not like he owned a car or anything.

"I was sure you could fly or something."

"Humans can't fly, you know."

Humans probably can't throw punches like Saitama either, but that was besides the point.

The building they arrived at was less than impressive and Genos took it all down in one shot. Saitama couldn't help saying it was kinda mean - the bad guys probably prepared all sorts of traps for them. Genos looked sorta guilty and Saitama let a little smile slip.

Eh, in the end it did save them time...

They weren't even halfway through the basement corridor when this giant... monster bug (?) thing (what the hell was it even?) slammed Genos into the wall.

"Genos?"

It all happened so fast Saitama barely had time to register what the hell was going on.

"Huh? Hey-!"- He was okay, right? His head was in the wall but he survived worser things... right?

"I am Carnage Kabuto!"- The monster slurred, spraying spit everywhere, -"We got a combat experimentation room. Let's do this in there."

Saitama felt a strange tug in the pit of his stomach. It was probably just the weight of responsibility he had for his newly found disciple, but somehow he felt obliged to destroy that smug monster bastard.

"You turned Genos into a piece of modern art. Fight's on!"- the conviction in Saitama's voice surprised even himself, but there was no way in hell he'd back down.

The creepy giant monster guy was taking his sweet time explaining the combat room (Saitama really didn't care), when suddenly a spray of fire hit him from across the room.

Phew. Genos was okay.

Even more than okay, judging by his enthusiastic fighting-

Oh, and now he was flying this way. Saitama caught him easily enough, but the kid was twitching and convulsing, sparks flying everywhere. Yet he still wanted to fight despite being all broken up and-

And suddenly, Saitama felt concerned. Legitimately concerned.

Was the kid suicidal? Or maybe just masochistic-

Saitama, as his master, couldn't possibly let him go back into the fight, -"Your face is all cracked. Don't push yourself."

Genos didn't listen - he simply blasted more fire at the monster, who easily deflected it with just his breath.

After the fire died down around them, the feeling in the pit of Saitama's stomach got worse, -"Genos, you okay!?"

"Y...es..."- the kid barely whispered. He looked damaged, but, in all honesty, the worst thing about his condition seemed to be his hair.

"No you're not! Look at your head!"

Now that was something horrifying. And that ugly monster just laughed!

Genos was still struggling, still trying to stand up and fight. Saitama held a hand up to his chest, settling him down. This kid was in no position to fight that monstrosity. So it was up to him.

Saitama was ready to take him on, and give him everything he's got, -"Don't disappoint me now."

And then the monster attacked... no, almost attacked, almost hit him with his full force when suddenly-

. . .

He should've seen it coming. The coward fled to the other end of the room before Saitama even had a chance to turn around and face him. What a waste of time.

"What are you doing? Hey."

But the monster looked... terrified. Disappointment was written all over Saitama's face - he turned out to be just like the rest, quivering before him, asking him ridiculous questions about his strength.

Fine.

If that monster, and Genos, and that scientist guy (where did he even come from?) all wanted to know the secret to his power so bad, he'll tell them.

• • • • •

S-Sensei... you are so...

"Full of crap!"- Genos couldn't help himself. Just what the hell was Sensei saying?

"That is nothing but standard strength training!"

That secret... the secret to Saitama's strength... it was complete and utter bullshit. One cannot possibly get this strong just by doing a hundred push-ups every day. It's just- it's just stupid!

He did not spend 4 days observing Sensei just to hear this-

Was he intentionally misleading all of them in order to keep the secret to himself? Was that just all a prank?

"I... I have to get stronger. I didn't ask to study under you just to hear jokes!"

Maybe Doctor Kuseno was right. Maybe Genos was way too rash in his decisions. Maybe Saitama wasn't as great of a person as Genos thought-

"Genos... You may not believe me, but that's really all I did."

Genos felt something in his chest tighten. That was... ridiculous.

All of it was ridiculous.

And yet Sensei said it with such sincerity in his voice... Mixed that utter confusion on his face - it was hard not to believe him.

That was when the monster started moving again. He started to change his form, his strength practically vibrating throughout the room. Genos saw the only exit close up - this was it.

All he had left to do was to believe in his Sensei.

The monster was easily punching Saitama all over the room, the latter completely unresponsive. Genos couldn't help but feel panic rise in his gut.

"S-Sensei?"

He wasn't attacking. He allowed himself to be pummeled and yet he didn't seem to be struggling whatsoever. Why wasn't he fighting ba-?

But even before Genos could finish his thought, it was all over. A single punch to the monster's chest took out all of it's ginormous torso, leaving only the legs behind, remains spraying all over the room.

Genos knew how tough the monster was. His best efforts were easily deflected. The monster simply toyed with him, and now he was dead - at Saitama's hands. How could one man possibly possess so much power...

One man, who was now standing on his knees, yelling something about messing up.

Sensei? What in the world...

Oh.

Oh.

Wait a second. Did the monster say Saturday...? So that's why he-

Right...

Just then, Genos suddenly understood. Saitama was just as clueless as everyone else about his enormous strength. He didn't know the secret himself.

"I'm pretty sure he's upset about this,"- Genos decided to explain to the completely speechless professor, holding up the Saturday sale poster.

The man held took in his trembling hands as Genos made his way over to Saitama.

"Sensei, the store closes at 10 pm. That is about four hours away. If we really hurry, we can make it."

And maybe not understanding was just fine. Maybe not knowing is a part of what made Saitama so special.

"I'll make it if I hurry?"

"Yes!"

In any case, he was now more resolved than ever to follow this man.

"Let's go, Genos!"

"Yes, Sensei!"

And maybe one day, they could figure out the secret to his strength together.

• • • • •

He never did go to the sale with Sensei that day.

Halfway to the supermarket, Saitama suddenly stopped and turned around to face Genos.

"Uh, dude. Shouldn't you get fixed first?"

"I'm completely fine, Sensei!"- and he really was. A little scratched here and there, a little sparky, but he was mostly okay.

"You also gotta do something about- that,"- Saitama pointed at his head and Genos felt a little embarrassed, running a hand through the puffy mess. He probably looked silly right now, -"You're also missing an eye."

"Really, Sensei, it's okay. The sale is more important right now."

"Wha- No way. The sale is not more important than having you fixed up."

There was a moment of silence between them as neither knew what to say. Genos didn't know how to convince Sensei he was fine. Really, he's been through much worse. At least he wasn't missing any limbs. 

"I can go with you, if you want."- Saitama finally said, shrugging and not really looking his way.

"Huh?"

"To get you fixed. I can come with you."

"But the sale-"

"Oh, there will always be another one."

Genos's eyes went wide. The sale, which Sensei was so distressed about earlier... he was willing to completely abandon it because of him! Sensei's kindness knew no bounds!

"No, Sensei! You go to the sale! I will get to Doctor Kuseno's just fine by myself!"

"...Whatever you say, man. Just get there safely, alright?"

"Yes!"