Work Text:
Kaigaku had been called many things during his short life on Earth.
Bastard, ugly, dumb, good-for-nothing, worst big brother ever, “heartless demon who took the last ice cream bar from the fridge” had all been flung his way at one point or another. He was no stranger to any unsavory insult that a person could invent, no matter how creative they may be, but he would never deny that he didn’t deserve at least some of these titles. Kaigaku was a bastard, he was a horrible big brother; and when Zenitsu texted him during the younger’s school’s lunch break in all caps, he fully intended to turn the screen face down and ignore whatever he had to say. But when his phone continued to buzz, the device vibrating so much it now dangled precariously off the edge of the couch, Kaigaku quickly realized the futility of his feigned ignorance before he snatched it up and grimaced at the barrage of notifications that blocked the entire screen.
Annoying Useless Ugly Crybaby: i need your help
Annoying Useless Ugly Crybaby: i need my wonderful, amazing, one-of-a-kind older brother to help his younger sibling
Annoying Useless Ugly Crybaby: pls don’t ignore me, Kaigaku
Annoying Useless Ugly Crybaby: PLEASE.
Annoying Useless Ugly Crybaby: ANSWER YOUR PHONE BEFORE LUNCH ENDS
Annoying Useless Ugly Crybaby: IM BEGGING YOU
Even while Kaigaku backread the messages, Zenitsu continued to spam his poor phone even though they devolved into simply spamming the word “HELP” a stupidly high amount of times that it started to make his device overheat. Kaigaku had half a mind to ignore the younger kid, but he also had an inkling of a hunch (a hunch supported by years of living with him) that the messages wouldn’t stop completely without SOME acknowledgement from him.
Kaigaku didn’t think twice before responding with a simple: “No.”
He didn’t even have time to close the screen before three dots immediately popped up, signaling to Kaigaku that Zenitsu had been hunched over his phone, anxiously waiting for a reply to his text spam.
Annoying Useless Ugly Crybaby: can you call?
Kaigaku was a mere second away from typing another “no” before his phone lit up with Zenitsu’s contact photo, a blurry picture of him face down in the dirt after failing to jump over a hurdle during one of their track meetings. In hindsight, Kaigaku wished the picture had been clearer but he had been laughing too hard at the time.
He declined the incoming call and fluffed the pillow behind him, already anticipating the daily nap he manages to squeeze in in before work until his phone distracted him again with the tell-tale vibration of an incoming text.
Annoying Useless Ugly Crybaby: DON’T BLOCK ME. ILL DO ANYTHING YOU ASK. JUST PLEASE HELP
Kaigaku bit back his first reaction of unleashing every derogatory insult he could think of, but instead, channeled his frustration into a much more lighthearted groan of displeasure and dramatic hair pull.
Normally, Zenitsu wouldn’t pester him to the lengths that he was currently undertaking. Normally, Kaigaku wouldn’t be considering actually hearing him out. Apparently, today would be full of abnormalities.
Against his better judgment, Kaigaku decided to answer his younger brother’s pleas and call him back. The phone hadn’t even completed its first ring before it was abruptly cut off as the person on the other line answered it. Kaigaku replied immediately, not wanting to waste any more of his time.
“Whatever you’ll ask the answer is-.”
“I need you to beat me up.”
It was a demand that had come so quickly that Kaigaku could only pause to blink stupidly, his mouth agape as the words processed slowly in his mind. He visibly struggled to understand what he had just heard even though Zenitsu wasn’t even able to see his facial expressions.
“You want me to what?” Kaigaku asked incredulously.
“Exactly what I said!” Zenitsu whined, the pitch of his voice rising with desperation and possibly slight delirium.
Did he wake up in an alternate universe?
“Are… you okay? Do you need to see a doctor? I won’t take you, but maybe one of your dumb friends will. Pass me to one of them.” Kaigaku hoped that Tanjirou was nearby, the little twerp would do his best to take care of Zenitsu since that other weird friend of his would be useless and probably would just challenge him to a race despite their distance away from each other.
Zenitsu persisted, “I’m fine! Just be quiet and let me explain. I want you to pretend to fight with me. You’d just throw a few fake punches and then I fight back and neither of us get hurt.”
His voice suddenly dropped, pitch frighteningly low and, if Kaigaku didn’t know any better, intimidating as he muttered, “This is my last chance, my back is against the wall here. There’s someone I have to impress and if they see me fighting back against the big bad guy then they’ll HAVE to think I’m cool and give me a chance! You’re the only person I know who can do this. Please, Aniki...”
He just had to use that dumb title too.
Kaigaku pinched his nose and sighed. He should just hang up on him without replying back. It was a stupid plan. A complete and utter failure of a plan. Kaigaku could already think of a hundred different ways that this could backfire and over half of them were solely because of Zenitsu and his inability to act normal. Though, Kaigaku mused, this kind of plan did go hand-in-hand with the yellow-haired boy’s completely absurd way of thinking. And some twisted part of him wanted to see it crash and burn in front of his own two eyes. Also he had a feeling Zenitsu would bother him the entire day or even visit his work until he relented.
“And what’s in it for me?” Kaigaku asked, leaning against the couch’s armrest. There was no conceivable way he would go along with this, miss his nap, and not get something in return.
“I’ll do anything you ask. I’ll give you my dinner, I’ll give you all my money, I’ll do the dishes this week…” There was a wet sniffle heard from the other end of the line.
“And?”
“AND? What do you mean ‘and’?! I just offered you everything I have, and you still want MORE from me?”
Kaigaku started picking at an especially long, unkempt fingernail, this would be all too easy.
“Oh, did you say something? Did you talk back? Must have been the wind. Well, it looks like I’ll be going now so-“
“WAIT, WAIT STOP. I’ll… Ill do all of your chores for a month.”
Kaigaku smirked. Bingo.
“Hm…. Well when you put it that way, I don’t see why not. When were you planning this thing to happen?”
There was a cry of relief of happiness and of wet snot in an utterly disgusting combo.
“THANK YOU! YOU’RE THE BEST!” The loud outburst shot straight to Kaigaku’s eardrums and rung painfully, he leaned away from the speaker. “Can you meet me after school? It won’t take long! And did I say that you’re the best brother that I have? Because you really are!”
Kaigaku clicked his tongue, “I’m your only brother, idiot.”
There was a brief silence shared between them before the meaning of the other’s words struck him and the call cut off right as he let out an admittedly undignified and infuriated, “HEY.”
Kaigaku bit his nail and flung his phone to the side. By all accounts he should stand up Zenitsu and just catch up on his nap, but Kaigaku really wanted someone else (other than him) to fold and put away all the clean clothes that he usually kept in a sloppy pile next to his bed. So with horrible and vile curses let loose under his breath that would make a mother cry, Kaigaku put his shoes back on and left the house.
--
Unfortunately, Kaigaku knew the route to Zenitsu’s school like the back of his hand as he had attended it and graduated the year before. That also meant that most of the teachers knew him by name and he couldn’t really pass as a regular student anymore without being brought into the principal’s office for an interrogation on what the hell he was doing back there and if he planted a stink bomb somewhere (it was only ONE time and Gyuutarou snitched on him even though the bastard had helped him hide it).
Kaigaku hoped to sneak by unnoticed through the front gate with the hustle and bustle of the kids heading home for the day acting as his cover but the dreaded sight of a P.E. teacher standing guard at the front gates in blue sweatpants with a whistle at the ready made him falter. Mr. Tomioka had eyes like a hawk, the emotional vulnerability of a rock, and the ruthlessness of an underpaid teacher. Kaigaku quickly turned around and started walking back. Disciplinary action and a mark on his record for trespassing was the last thing he needed right now.
He got out his phone and texted his last contact,
K: There’s a teacher guarding the front gate.
With any luck he could still go home and not go along with any of Zenitsu’s plans ever again. The response, however, was immediate.
Annoying Useless Ugly Crybaby: can you get a visitor’s pass?
K: You wanna get roughed up by an honor’s student with straight A’s and a hall pass while you’re at it?
Annoying Useless Ugly Crybaby: ugh. just jump the fence from the side.
On a better day, he probably would have been impressed that Zenitsu knew about the blind spot by the shed that coincided as a place to store the sports clubs’ supplies and also allowed for the troublemakers of the school to sneak in and out. Today was not a better day.
Making his way around the school and with all the grace of a bumbling elephant, Kaigaku lifted himself up the fence, got his foot stuck In between the chain link fence as he leaned over to switch off to the other side, then proceeded to try his best not to lose his grip and dislocate his leg. With some harsh and uncoordinated tugging, Kaigaku managed to free his foot but a severe miscalculation of his balance led him to accidentally flip himself over as he fell onto his back and hit the hard dirt.
As he stared at the clouds lazily rolling by, Kaigaku felt himself undergo an entire monologue in the span of three seconds. Zenitsu wasn’t worth it. Clean, folded clothes neatly stored in his dresser would never be worth it.
But he was already there, his mind annoyingly retorted.
There’s a billion different ways can get back at Zenitsu later, it supplied.
And against every one of his better judgments and aching limbs screaming at him to go home and rest, Kaigaku brushed himself off and took out his phone.
K: I hope you’re ready to clean my dirty underwear and socks for years to come.
K: Where even are you?
Annoying Useless Ugly Crybaby: in back, where the extra lockers are. i see you.
Kaigaku scanned the area, thankfully devoid of any teams practicing in the yard or loitering students before he spotted a certain blur in the distance with yellow hair that was frantically waving at him from a set of abandoned lockers. He made the long walk away to the other and instead of a normal and pleasant greeting, he was met with, “Wow, you look rough. Did you get into a fight on the way here? You have dirt on your face.”
Kaigaku’s head ran with a million insults that started with calling him “pizza face” and ended with saying “no one will ever love you” before he shook his head and thought better of it. Another time, another place.
“Shut up. I’m already here. Just get on with it, the sooner we do this the sooner I can leave.”
“Oh! Well,” Zenitsu rubbed the underside of his nose and smirked, “You may be surprised but I’ve found my one true love. Her beauty is unmatched and she’s so kind and generous… plus she smells so nice… Ah, Nezuko-chan.” The little freak hugged his arms as he stared off not the literal distance and probably imagined his dream girl in his arms.
“I haven’t proposed yet, but our relationship just needs a little push. That’s where you come in! Just throw a few FAKE punches at me and I’ll throw some back and I’ll sweep her off her feet and propose in the morning.” Zenitsu turned towards hm.
“But they have to be fake punches.” Zenitsu stared right at Kaigaku, his piercing gaze almost unsettling.
“Punches that aren’t real.” Zenitsu wasn’t blinking, “Kaigaku.”
He turned the other way, losing the staring contest as Zenitsu had taken a big step towards him like a hypnotized zombie.
“I heard you the first time.” Kaigaku said.
“No, do you think I’m stupid? I know that you’ll take this chance to hurt me for reals. I don’t actually wanna die before I marry Nezuko, okay?” Zenitsu glared up at him, his eyes as big as the china plates that Kuwajima uselessly kept as antiques.
“OKAY?”
Kaigaku’s eye twitched in irritation, his temper getting the better of him, “I said I heard you! Be quiet or someone will hear you. I’ll go along with your stupid plan, but when it blows up in your face just now that I told you so.”
“Huh? Told me what?” Zenitsu asked.
“Told you that you’re stupid.” Kaigaku replied.
Zenitsu gave him an unimpressed look before he lifted his thumb and index finger to rest on his chin as he dramatically looked up at the sky. The direct eye contact with the sun made him squint and look as if he were about to sneeze.
“I’m really not one to brag but I feel that this could actually work! Life might finally be looking up for me.” Zenitsu said before he brushed the bangs from his face and gave Kaigaku a pat on the shoulder.
“Don’t worry, when I have beautiful little grandkids, you’ll be able to visit them once a week, maybe even more if you buy a nice wedding gift.” Kaigaku sighed and without missing a beat, Kaigaku took Zenitsu by the ear and pulled hard. The younger hunched over, losing his balance as his eyes teared up in pain.
“OW OW OW! STOP, IT HURTS! I HATE WHEN YOU DO THIS.” Zenitsu flailed, trying his best to grab Kaigaku by the hand until he was suddenly let go. Zenitsu huffed, glaring at him as he nursed his sore and tender earlobe.
“Ugh. You’re barbaric… completely evil….”
He grumbled some more insults under his breath, Kaigaku managed to hear Zenitsu call him “demon” and a “loser big brother” while he peaked his head out to the side of the building until he suddenly jumped back as if he had been drenched in boiling water. He bumped into Kaigaku, the back of his head slamming into his jaw as the older male felt a sudden flair up of pain along with the early beginnings of a nasty tension belonging to a burgeoning headache.
“Ow! Watch where you’re-“
“SHUT UP, THEY’RE COMING.” Zenitsu shushed him, his index finger landing on Kaigaku’s lips as if to quiet him. His patience was running on empty fumes. “I saw them. Just do what I said and act natural!”
Zenitsu huffed, brushed off the invisible dirt on his uniform, fixed his tie, then stood on his tippy toes to make direct eye contact with Kaigaku. His face was exaggerated, frown so deep and crude with eyebrows raised high that it appeared as if he were wearing an oni mask. Kaigaku thought he looked uglier than normal and that was an achievement on its own.
“Hah? So, you wanted to fight with me? Do you even know who you’re dealing with? Me? ZENITSU? AGATSUMA ZENITSU? THE PILLAR OF OUR COMMUNITY WHO’S HERE TO STOP YOUR TYRANNY OF EVIL?”
Any person who had spent two minutes in Zenitsu’s presence would agree that the young boy was loud, but to be shouted at directly with only a short amount of distance between the two of them might as well have been a death sentence to his ear drums.
Guess it was time to play along with this dumb script, he unhappily realized.
Kaigaku cleared his throat, trying his best to appear as casual as ever while he used his pinky to subtly massage his tender inner ear as he feigned disinterest.
“And you’re the brat who keeps messing with… my men. You trying to uh, start something with us? Or something? Because if you are, we’ll make you regret it.” Kaigaku winced at his own stilted words, he wasn’t very good at off-the-cuff thinking. It was an ability that, unfortunately, came much more naturally to Zenitsu.
Out of the corner of his eye, he could see the silhouettes of two students at the corner of the building, frozen in place as if they didn’t know what to make of the strange scene.
“Just try me, you punk with ugly bangs! I’ll do to you what I did to your other fifty lackeys! Oh, did I say fifty? I meant one hundred!” Zenitsu by now was quite literally screaming at him. If he was any louder a teacher might come to check what’s happening, “And if you move another muscle, I’ll show you what makes the Agatsuma family line so feared!”
Kaigaku almost wanted to laugh. Zenitsu doesn’t even know the Agatsuma family line, he was adopted as a baby and Kuwajima picked out that name for him.
He rolled his eyes before he smoothly gripped Zenitsu by the collar and slammed him hard against the wall, the younger’s eyes widened in fear at the action, reality settling in as he realized how vulnerable the change in position made him.
“Kaigaku, not that hard!” He whispered in a panic, before he cleared his voice, “Hey, watch what you’re doing! You must be really eager for a fight, no-brained punk! Yakuza informant! Gang leader! You must have an impressive resume for a villain like you!”
Kaigaku coughed to cover up a laugh, he could see Zenitsu struggle to keep the upturn of his lips under control. He raised his fist, the limb aimed level at Zenitsu’s face as he tried his best to remain in-character.
“Oh, now you’re REALLY asking for it, don’t say I didn’t warn you!”
The two heard a commotion to their side and frantic running as an unknown voice yelled, “Stop, let go of him!”
Kaigaku barely had enough time to turn his head towards the source of the outburst before a fist crashed into the side of his face. He lost his grip on the younger, Zenitsu yelped as Kaigaku briefly stumbled back before crashing to the hard ground. Stars danced across his vision as he faintly heard an “Are you okay? Did he hurt you?”
He groaned, trying his best to raise himself onto his elbows as he saw the world in double vision, his ribs and face screamed in displeasure. A young man with black hair and reddish tips kneeled next to Zenitsu, who had fallen onto his knees and looked deathly pale as his eyes rapidly switched from the other boy to Kaigaku. When he made eye contact with Kaigaku, the yellow haired boy only grew more nervous as he chewed on his nail. Kaigaku guessed that he either looked like shit, or like he was about to kill someone.
Misunderstanding the fear, the unnamed man turned and glared at him.
“Stay right there! Why were you two even fighting in the first place? One of you could’ve gotten seriously hurt!“
Someone did get hurt and you were the sole cause of it, Kaigaku angrily thought back.
Zenitsu reached out and held the other boy by his sleeve, the material wrinkling in strong grip, “Tanjirou, stop! Stop it! Don’t agitate him!” Zenitsu hissed.
The brunette’s (so this was the famous Tanjirou that he heard all about, Kaigaku vowed to remember him for the rest of his life) expression immediately changed as he turned back to Zenitsu, his eyes softening and concern flooding his face as he softly touched the other’s arm, “He was about to hurt you, Zenitsu!”
“And he’s about hurt us if you don’t knock it off! Why’d you meddle in this! Stop meddling, you meddler!” Zenitsu’s face was red, if it were from screaming or from embarrassment, Kaigaku would never know.
All traces of mirth and enjoyment at the ridiculous situation now completely gone, Kaigaku struggled to get to his own feet, almost hunched over as he touched his cheek and visibly recoiled at the pain. Zenitsu pushed Tanjirou away from him, hesitantly reaching out towards the pants’ leg of his older brother.
“Uhm. Wait… Kaigaku, I… “
Kaigaku leaned down and slapped his hand away before it could make contact with him. The hurt look on his face might’ve been amusing in any other situation that didn’t involve one of his eyes being so swelled up that he could barely open it.
“Whatever. You win for now, Agatsuma.” He huffed, turning to limp away before he paused and looked over his shoulder, “But if you set foot on my turf again, I’ll make you regret it.”
Zenitsu paled so much he was identical to a corpse. Kaigaku continued to walk, pointedly ignoring the other spectator to this entire debacle, a younger girl with a bread in her mouth who only blinked curiously at him and his injuries.
As he walked away, the last few words that he could hear were, “Wow, what a jerk! Let’s go tell a teacher, okay Zenitsu?”
--
Kaigaku did not show up to work that day. He used the first official sick day of his life to nurse his new black eye and the big bruise forming across his cheek. When he later checked his phone after trying to soothe his injuries with a frozen bag of peas and saw that Zen had sent a simple, “Thank you”, he changed his younger brother’s contact name from “Annoying Useless Ugly Crybaby” to “Wimpy Baby Bro”.