Synopsis: Prince Miya Atsumu despises his knight Sakusa Kiyoomi. They both can at least agree on that about each other. Yet upon Atsumu juggling his princely duties, needing to find a suitor, and getting himself to grasp the concept that he will be king in a year's time, he unexpectedly finds himself writing this down: Rule No. 1–– Don’t Fall in Love with your Knight.

CHAPTER 1– The Future King

Tags + Tw (please read): Sakuatsu, Knight x Royalty AU, Sakusa Kiyoomi, Miya Atsumu, Injury Chapter Summary:  “Ma’ god that took you a melon! Yer knees gettin’ bad or somethin’?” Atsumu says with full confidence. “I think you mean a millennium, your highness.” And this is the future king? Sakusa Kiyoomi has been asking himself the same question for years. Fandom: Haikyuu Section: Fanfics, 2/1/2025 A/N: GUYS. I’m literally shook. I've had this fic in the basement since AUGUST OF 2023. HO!!!!!! THAT’S NEARLY TWO WHOLE ASS YEARS. This shit might have been EXPIRED. But yk how candy doesn’t expire yea that’s why we’re here… still eating this shit up. I think it’s just that I’ve come back to it off and on tbh. I only recently started adding/fixing a lot in this fic cuz you already know I had to come back to my roots. Sakuatsu is my otp, my forever my everything ya feel ya feel ya feel? Time passes by so quickly, and upon editing this fic I realize it is still number one nowhere near finished and two that I’ve grown so much as a writer. Guys.. this fic might be a little too important to me so enjoy it. Besitos.

Atsumu couldn’t wait for the day that he could get out of this grimy palace that he calls ‘home’. Although practically impossible, he’d grown to loathe the smell of aging bricks, pragmatic books, and all the royal duties that came with it. On the contrary, the most intriguing part of its entirety is the open window of the east tower where his royal knight trains just below everyday precisely in the afternoon.

“Omi, what cha’ doin’?” Atsumu yelled, leaning smugly over the edge. 

On occasion when Atsumu is in danger; so almost never, Sakusa would answer his vexing calls from that window. He’d perform the same motion regularly of shooting a barely acknowledging glance at the prince without a word, and promptly continue with his routine of slashing soulless dummies.

Atsumu clicked his tongue, and counted: “that’s day 100.” He pranced gallantly over to his desk opening the seemingly only neat part of the cacophonous desk scattered with various texts yet to be read. He smirked, picking up a single sheet of paper between his fingers from a uniform stack. He dipped the quill in the ink, biting his lip as he drew a single tally mark under the rather conspicuous title: ‘Omi so Boldly and Gracefully Ignores the Future King’. Out of the several of these papers, which he kept proudly under his bed, his favorite one he’s come up with is: ‘Reasons why my Knight Should Be Rightfully Banished from my Side’. He’s profoundly boastful about that one, in fact he told Sakusa himself, who expectedly disapproved, but agreed that it was the most ‘royal’ he had ever sounded when addressing someone. Every one hundred days was another taunting title, another tally, another reason for Miya Atsumu to amplify his own spite for being stuck with the famously noble knight known as Sakusa Kiyoomi.

The prince looked at the tally as though it were his latest and lengthy masterpiece. He twiddled with the quill between his fingers, grinning at all one hundred standing lines and slashes until finally rising and returning to the familiar tower cill. 

“C’mon Omi!” He said, pasting his palm to his cheek, moping in distress mockingly. “Aren’t I more interestin’ than those stuffed dummies?”

Kiyoomi heaved. Full armor, and one of the hottest summer days. He couldn’t have thought of a worse way to end training today.

Atsumu, in his own twisted, spoiled, princely fashion way, couldn't find a more perfect day to cause an inconvenience. He grabbed his throat, sticking out his tongue as though rain would suddenly start falling and save him from his imaginary decade long drought. Swimming through the humid air he pleaded,“Omi! Omi! I dun’ feel so good. I think ima faint from the heat!”, buckling his knees for extra effect.

The sweaty knight looked up and cocked his eyebrows at the immersive sight. It eluded him every time: how Atsumu could imagine these intricately deluded scenes on the spot, and yet never learn to memorize his own public speeches when it really mattered. There were no “ums” no “ohs”, or “I forgots”, when it came to Atsumu’s daily mission of pissing him off– and everyday was a flawless victory. It’s all irrelevant though, only a measly nuisance that frequently appears within his duty to protect the heir. Miya Atsumu is mediocre: and perhaps, Kiyoomi thought, with utterly desperate hopes, that it’d finally come clear as day when that crown eventually sits on his head.

He shrugged his shoulders down, throwing his head into the shadow of the tree, finally pulling his sword from the torso of the training dummy. Atsumu observed quietly, taking Kiyoomi’s motion as sweet, victorious obedience. The knight met the gaze of his prince, who was staring amusingly at the site. Sakusa rolled his eyes, pacing dreadfully to enter the tower doors, readily obliged to Atsumu’s apparent ‘danger’.

The prince snickered.

—

Atusmu loved to play pretend. Fortunately for Sakusa Kiyoomi, he stopped joining the fun promptly at seven years old when he’d begun his knightly training. Now, at 22 years old, he had the extreme privilege of protecting the life of his kingdom's wealthiest man-child who was anxiously bouncing his knee, with his feet flat on the floor wearing the expression of overwhelming concentration upon the pages of a book covering the concepts of world trade.

The focused prince only broke out of his haze when the wooden door slammed open, and he thought that  the stoic knight might’ve just broken the door against the tower bricks. He hid the grin behind the leather cover of his book, and peered conveniently over the top of the pages. Atsumu glanced audaciously just over his eyelashes, while Kiyoomi lasered his gaze sternly into the back of the prince's skull. He wants nothing to do with me, Miya thought; It’s astonishing.

“Prince Miya.” Sakusa bluntly muttered. Atsumu shook his head back into his fantastical persona of an intellectual regal, taking careful intentions of poshly placing his book onto the polished wood desk. He straightened his back passively, folding hands meticulously and clearing his throat, “Omi.”

The knight sighed, “What ails you this time?” Atsumu routinely waited for that nonchalantly gravitational tone like fresh breakfast after a long slumber. Devouring his knights' undivided and devoted attention was one of his many joys, and there was no other pleasure than absolutely thriving in Sakusa Kiyoomi’s apparent frustration. “I told ya’ Omi it’s this heat!”, and living for the tense jaw that rested above that sturdy, mole freckled neck that responded back to the dramatism was no exception.

“No, Prince Miya,” Kiyoomi spat out his response as though this was no matter for posing rhetorical questions. He knew his prince well enough to know that his stupidity wouldn’t allow him to live in such stable, mature things like absolutes. A futile remark always led to that sort of situation, and Kiyoomi saw it all play out ten steps ahead. “What is it really, because I can’t make the goddamn sun go any further from the earth.” He continued.

His gritting pearly whites were always the cherry on top. A daily afternoon satisfaction that never fails: that elicits from Atsumu’s extravagantly irritating efforts. It’s just unfortunate that Sakusa Kiyoomi happens to be the very heart of it all. It’s also a shame, almost pitiful, for the prince that even in his own gaudy act he still stutters without intention. “Tch. I dunno,” Atsumu trails. “Just go, and uh, fetch me a water or somethin’.”

“Yes, your highness.” Sakusa bowed quickly, and turned his back to the heir. Atsumu breathed, searching for something else. “Oh and Omi!” he shouted, making the knight hesitate to take hold of the door knob. Sakusa nudged his head slightly, offering his ear to the last part of the prince’s request: “Make it cold!”

Atsumu could see the loathful shudder that traveled from the knight's feet to the back of his curly-haired head. If Sakusa Kiyoomi had the ability to make the very earth shake for a mere second to scare the living shit out of Miya Atsumu, he would’ve done it twice; so that not only would the prince shut up, but start crying in fear of his demise. But luckily enough for the blonde royal, he doesn't have to fear, and he’ll never have a reason to. Not as long as he has his knight by his side, not as long as he’s the heir to the throne– and Sakusa Kiyoomi knew better than to let his pent up anger get the best of him. It was a dual-life, this life of duty and valor that was the best outcome the universe could’ve possibly come up with for him. 

“Stop calling me that.” he stated for the millionth time, opening the door and closing it behind him.

And of course, that all came with a price. Life will never be bliss the way we’d like, Kiyoomi knew that better than anyone. And so, he proceeds to drag himself down the stairs to seek cold water for his parched prince.

—

Atsumu was on the last page of a book he just about took in nothing of. Every other sentence was skipped with only a blot of transition words sticking to his memory, and all the relevant content seemed to slip even when he reread it. Atsumu saw no point in teaching him anything since he had turned eighteen four years ago, the king had insisted all of his ‘fun’ books be switched out for the books that addressed the royal laws and duties of his soon to be kingdom. He learned quickly that the overload of information wasn’t meant for his kind of processing, it always went one ear out the other even when he tried. He nagged about how boring all of it was to Sakusa, complaining about the quizzes that took place promptly every Sunday by his royal tutor, who consistently gave slaps on the wrist for failing or just barely passing. Long lectures would always follow from several sources as if the physical consequence wasn’t enough for the prince, of ‘one day you will be king’, questions of disbelief like ‘did you even read the books?’, and blatant chastising comments of ‘how improper’ he entirely is. That knowledge stretched further than the palace walls throughout Atsumu’s adolescent years, and it became widely known throughout the kingdom that Miya Atsumu was stupid. Plain out stupid, conceited, selfish, and childish. The prince tried to believe that it all wasn’t so hopeless if he really wanted to give himself credit, it’s not like he wasn’t trying, and he certainly wasn’t proud of this unbearable fact either. He just knew that deep down his subjects probably knew that they were utterly wrong about him– that this crowded perception of him was merely an archetype that would gradually pass he finally got to rule. He reassured himself that he’d prove this notion, and believed it truly. 

But absolutely no one in the entire kingdom, not even the generous king himself, could’ve possibly believed in Miya Atsumu more than Sakusa Kiyoomi.

“Prince Miya, your book is upside down.”

And there stood a flushed knight with a glass chalice of water, dreading the sight of the clearly innovative prince.

“Omi!” Prince Atsumu shouted, nearly throwing his book five somersaults in the air. He pushed out his chest, swallowing in recoil from the sudden jolt his body had thrown him in.  “Ma’ god that took you a melon! Yer knees gettin’ bad or somethin’?”

“I think you mean a millennium, your highness.”

“Nuh uh, it’s just the heat gettin’ to me.” The prince pursed his lips averting his gaze from Kiyoomi. He held his hand out and faced himself nonchalantly towards the window, “Now, come hand me my cold chalice.”

Sakusa let himself have the pleasure of releasing a soft scoff, so maybe by some miraculous acknowledgment Atsumu would drop the act. He motioned himself forward to Atsumu’s desk annoyingly close to where the prince's feet rest at the top, ‘reading’ his book ever so studiously. Just at that very second, Sakusa swore the prince’s waiting hand was in a sort of twist. He couldn’t figure out what it was about today, maybe the fact he was perspiring nonstop during his warmups, or the fact his knee let out minor twitches here and there whenever he struck his foot forward. He deduced it was just the odd configuration of Miya Atsumus' pretentious face appearing one too many times today, more than usual. But since when was he ever keeping count?

“By the way Omi, how ever so kind of ya tah’ remember I love my drinks in glass chalices… but I mean who else coulda’ known that, ya know me so well…”

Maybe it was just some recurring average that would suffice Sakusa Kiyoomi’s logic just for today. Today, he had zero capacity even with his astute wits to put up with the density of the prince. It was yet another box to check, not something to pay any mind, especially not his own.

“And Omi, ma’ lord I swear to my own father that I am just so grateful for ya’... Omi?

He knew better than that. Better than anyone in the entire kingdom that he just needed to let empty sentences, thoughts, and people trail off as intended– let it all wander somewhere past him in the pointless haze. Someday, he thinks, maybe it’d all have meaning as it moves effortlessly through him. Yet there’s something tranquil about the tepid warmth that hits the side of his face and pours into the rest of his body, cradling him into this suspenseful trance of sinking. Sakusa Kiyoomi, desperately grasping for conscientious resilience against a plunging weight three times his own for one of the more sparse moments in his life, finds himself submitting to the mystifying pleasure of comfort.

“Omi?” Atsumu double-took the oddity of the knight's hesitation. He observed as Kiyoomi’s face stood fixed and molded into a plain expression, as though every pore in his skin refused to breathe vitality into his soul. “Omi, my chalice, please. Are ya well, ya look as if you’ve seen a ghost.”

“Mmmmm…” the knight hummed, though not conscious of it.

“...Sakusa?”

Atsumu followed the heavy back and forth movement of Sakusa’s head, and the slow, drowsy close of his eyes. The prince forgot to react, in fact it wouldn’t dawn upon him even after the chalice sloppily falls out of his knight's two fingers that it shattered into a thousand pieces on the brick floor– and Sakusa Kiyoomi followed.

The prince left a moment of silence. Atsumu never thought he could experience such an upsetting sensation where his stomach could stop his mouth entirely from producing even a sound, and more importantly an incredibly solitary state where time itself could move without any sort of consideration for him.

“O-Omi!”

Atsumu practically squealed, launching himself out of his chair in a frantic haste. He shakily scans the entire room for an answer, capturing nothing but shuffled books, papers, and finally the grey brick wall. For Atsumu, even the wall was an appealing prospect to threaten his life. He thought maybe he could die in this moment: this was possibly the closest he had ever been to it after all; death. After all, it’s approximately 12:30 in the afternoon, he knows that because usually this is around the time Kiyoomi stops training for the day. Which also means, every one of the palace workers in the east corridor is on their break for at least fifteen minutes. But this couldn’t wait fifteen minutes, he thought, raking his delicate fingertips into his own blonde hair, Sakusa could be dying and Atsumu would’ve just witnessed it. How is he going to survive when the only knight that can handle him is dying? At the hands of the future king? Kiyoomi can’t go out like this– that's Atsumus' verdict. Not while the fainted knight in front of him holds one too many secrets and truths about him, not when he would have to go through the motions of explaining himself.

Rule No. 1 of A Guide to Being A Worthy Ruler, ‘always take matters into your own hands if possible with help’

 and of course there was no latter, so, promptly, the former.

I should check if he’s alive first, he thought. The skill isn’t really necessary for a ruler, but Sakusa showed him once. It was all brought up because Atsumu made a comment about how he thinks one of his worst fears would be to be buried alive. The knight invalidated the possibility, and the prince questioned whether it was a matter of wizardry, and that if Kiyoomi was really a wizard, he should’ve just said so and taught him a few spells. Atsumu jumped back when Kiyoomi brought two fingers to his delicate neck, and held it with light pressure. “There is a pulse here, just as there is one in your chest”, he’d say. Atsumu knelt down slowly, taking two of his fingers and bringing them to the crook of Sakusa’s neck. Atsumu shook, please don’t be dead, please don’t be dead, please. He pressed lightly to be met with the reassuring pulse of his knight. The vibration against his fingers left a feverish warmth lingering on the prince's fingertips, and he wiped the vast amount of sweat back on Kiyoomi when he retracted his fingers. Atsumu looked around gawking in realization that Kiyoomi had fainted from the heat. He glanced at the pieces of the chalice now into smithereens on the floor, wondering if his knight truly needed that water, why didn’t he just drink out of it? He wouldn’t have fainted.

This is all his fault.

Atsumu threw Sakusa’s arm over his shoulder and hobbled into a stance.

“Gee Omi, you’re heavy. Maybe think about losin’ some weight.”

Atsumu fumbled down the stone stairs of the east tower to the closest room available without help:

His bedroom.

—

Sakusa felt a heaviness on his head, and peculiarly his feet. He furrowed his eyebrows, slapping his hand over his eyes. His head pounded, and his heart thumped through his ears. “Hinata, how long was I out for?”

“Sorry, Omi. I’m not Hinata.”

Sakusa paused, sighing at the sound of the familiar accent.

“Oh.”

“Oh?”

“Oh shit.”

Atsumu tilted his head, a tinge of concern shaping his vowels. “Omi? Are ya well?”

Sakusa thought he should’ve just died instead of waking up. Here, anywhere but here would’ve been better than anything, even hell. sat up from Atsumu’s bed. He grips the soft sheets, searching for any consolation that he wasn’t already a dead man as it is. Sakusa has never messed up this bad. Maybe a few times his sword slipped from his hand into the wrong position, or he lost sight of Atsumu for a couple of seconds, but this was bad. Really bad. He messed up.

“No, No. Your highness, are you well?” It was the most wide-eyed Atsumu had ever seen him. He could’ve mistaken his knight's question for a coo.

“Omi,” Atsumu thinks he might be living in an alternate universe. Of course, Sakusa Kiyoomi would be the only one who could make him feel stupid enough not to be aware of where he was despite being the only completely conscious one in this situation. “I’m perfectly fine and dandy but-”

Sakusa didn’t wait for another word to slip out of the prince's mouth. His feet reacted first, throwing his weight out from under the covers and attempting to come to standing. His head knocked at his skull again, and threw him around in a second trance.

“Omi!” Atsumu watched as Sakusa’s body threw him around like a drunk dancer. “Please lay back down ya we’re burnin’ up in yer sleep I think yer ill and-”

“Your highness. Please.”

“No,” the prince stood to meet his knight's shifty gaze. “Omi I command you, rest!”

Sakusa threw his hands, “Your highness! If you will,” he said, almost barking through his teeth. “But I have just so ignorantly abandoned my duties! My duty to you!”

Atsumu jumped back at the sudden sternness. Atsumu was never barked at in such ways, as really most of the time he was the one doing so. And Sakusa, on the other hand, had always spoken to him in his usual knightley composure. Such a composure that he knew no matter how much he hated Miya Atsumu, he was just as much obligated to the Prince.

Sakusa digresses, his eyes softening at the sheer sight of the Prince's pale face and torn up pants.

Sakusa cleared his throat.

His eyes scan around the room, his head swiveling around to the door. “Does the palace know I’m here?” He sighs.

“No.”

“Are you going to do anything about it?”

“…No.”

“Why?”

Atsumu grips his sheet covers. In any other circumstance, Sakusa would’ve been promptly beheaded the next morning. Atsumu hated Sakusa. Hated that, no matter what he would always be babysitting him. Hated that, whenever Atsumu attempts to go on one of his bold excursions to escape from the palace, Sakusa was always two steps ahead waiting to escort him back. Hated that, Sakusa Kyoomi very apparently pities him.

“Well,” Atsumu pauses, struggling to meet the knight's dark eyes. “I wouldn’t do that to ya, Omi.”

His eyes flicker back, finding Sakusa’s expression to be unchanged. He never wavers, even upon utmost tension. That’s one thing Atsumu can at least admit he admires, maybe even envies about him.

“My god,” Sakusa whispers, pinching the bridge of his nose. “Let me have a look at you.”

Sakusa knelt down to where Atsumu sat on the side of the bed and began to examine the bloody holes in his pants.

Atsumu giggled, “So ya noticed huh?”

“Of course I did.” Sakusa blinked, pinching the torn material between his dexterous fingers. “Since when does a Prince like you ever allow himself to walk around with bloody holes in his clothes?”

“Hm.” Atsumu pouted.

The fireplace next to the bed crackled, interrupting the silence. Nonetheless, Atsumu couldn’t help but focus on the warm luscious glow that washed over Sakusa Kiyoomi’s features. Atsumu had never really taken note of any of it, except the two apparent moles just above his eyebrow. But now he had taken note of how full his curls looked in this illumination, and how just below his side burns followed a chiseled jaw, and even lower, a softly rounded chin. Sure, Sakusa Kiyoomi may have had some rough spots all over from training, and countless hours of fighting. But he looked as though he had just been freshly sculpted, or painted. Atsumu hates this, sitting here deciding whether he looks like a statue or a porcelain doll while his knight tends to his wounds.

And after the conclusion, how to make a nuisance out of it.

Sakusa lifted his head. “How’d you get them?”

“I carried ya’ over,” Atsumu stated, proudly. “I probably just got nicked here and there by the walls and floors. You were pretty heavy.”

“Tch.” Sakusa scoffs and tugs on the bottom of Atsumu’s pants, “May I?”

“Take em’ off?”

“No!” Sakusa jumped, and cleared his throat. “No. Just– I’m just going to lift them off your knees, Prince Miya.”

“Oh. Well yea…” Atsumu scratched his head. The innuendo wouldn’t hit him till later that night, before he goes to sleep. “what else we’re ya thinkin’?”

“You were the one who–” Sakusa pauses, capturing the genuinely puzzled look on the prince's face. Blondes. “okay. Proceeding.”

Sakusa lifts Atsumu’s pants gently and finds three wounds. One on his thigh, which was barely a scrape, and one on his shin which was the just of the same minority. But the worst of all was the still bleeding and tender one with a small piece of glass hanging out of Atsumus knee. Sakusa snarled.

“Nicked,” Sakusa clicks his tongue. “Is an understatement. You’re gonna be a lousy ruler, you know.”

“Oh yea? How da ya’ know that?” Atsumu challenges.

“Because,” Sakusa took the small piece of glass gently between his index and middle finger, pulling back swiftly.

“OUCH!”

“You save your knights,” he continues. “If I die, I die. And that’s at no expense to you. It shouldn’t be.”

“But Omi, I didn’t know if ye were dead. I dun know what I’d…” Atsumu trails. “What I’d do.”

“Do?” the knight scoffs. “You ask for help, Prince Miya.”

Sakusa hoisted himself up and walked over to the fireplace, where he discarded the small piece of glass.

Atsumu’s eyes follow the knight's motions, attempting to think up any excuse. “Well, they were all on break.” He swallowed, “I can’t just–”

“Doesn’t matter.” Sakusa answered swiftly. “They’ll help you and you shouldn’t feel sorry for it. They serve you.”

Atsumu's heart sinks. Sakusa pays no attention to the shift, and motions to the prince’s bedroom door. “Now I’m going to get a towel and some alcohol to clean you up. Just wait here.” And Sakusa Kyoomi hopes he does just wait. He knows he’d probably be dead in the next five minutes should anyone else see the prince in this condition. “Study for your next quiz,” he suggests. “I believe now that is, and should have been your priority.”

And before Sakusa can find the door handle, Atsumu finds a stroke of courage. “Well,” he blurts. “I dun really like that.”

Sakusa’s hand lingers over the cold metal. “Like what? Studying?”

“Nuh uh.” Atsumu says, shaking his head adamantly. “Servin’.”

The Knight cocks an eyebrow at the Prince.“Huh?”

“I don’t like that ya serve me.”

Atsumu enunciates every syllable like he could die on that statement alone. Sakusa goes quiet, and still air surrounds the room.

“That’s quite alright, Prince Miya.” He tries to reassure him accordingly. But he knows the problem isn’t the rest of the kingdom that will fall into his hands. “I’ll be gone anyways after you become king.”

Sakusa walks out, shutting the door tight. Atsumu stares, left to ponder on his next perplexion of the almighty royal quiz.

—–

“Sakusa, are you feeling alright?” A bubbly voice calls out. “You look hellishly pale.”

Sakusa squeezes a wet towel from a bucket and reaches for the cabinet. As if Prince Miya wasn’t enough of a bother, Sakusa Kiyoomi also had to bear the burden of sharing bed chambers with the eccentric Hinata Shoyo. But at least, he thinks, it isn’t Bokuto Koutarou– who is a neighboring knight of theirs.

“I’m alright Hinata.” he says, flicking the damp cloth out. “I just went all out today.”

“Again? Jeez.” the orange-haired knight, always full of expression gasps. “No wonder you're entrusted with the Prince, you train all day no matter sunshine or rain!”

“Tch.” Sakusa purses his lips into a pout. This is the one thing that is nice about his roommate: he gets an infinite pass to complain. “Well, it’s not always very peaceful.”

“Go figure…” And the best part, Sakusa Kiyoomi thinks, is that Hinata Shoyo agrees. “I mean honestly, who wants to watch over the Prince? He’s the royal ditz of the century.”

Oh, and he’s to Sakusa’s surprise, funny. “Yea, I know.”

But this time Sakusa walks the awkward line of the remark being funny and wanting to reject it. Hinata, observant as ever, leans against the counter pointing his lips at the lack of return Sakusa gives him.

“You sure you’re alright man?” The short knight's lips curl into a smirk. “I mean normally you’d be going off on the guy.”

The silence stretches alarmingly thin. “...I owe him a favor.” Sakusa almost mutters.

“A favor, huh?” Hinata tilts his head, following his eyes with the dark-haired knight pacing quickly to the door.

Sakusa swings it open, turning back only to briefly answer.

“Yea. And I forgot to say thank you.”