Chapter Text
“Everything is theoretically impossible, until it's done”
― Robert A. Heinlein
Tap.
Tap. Tap. Tap.
The sound of the pen against the desk is rhythmic, compulsive. It should help him focus, but it doesn't. His thoughts are louder. Messier. Sharper than usual.
Tap. Tap.
The lecture echoes distantly even though Sieun's eyes are glued to the board, where the professor is detailing something about the sympathetic nervous system, adrenaline, fight-or-flight responses.
Sieun is pissed.
He's beyond pissed. He's flooded. Dopamine withdrawal. Cortisol surge. Full sympathetic overdrive.
It's been exactly one week since Wooyoung said the words — seven days, twelve lectures, sixteen hours of disrupted sleep, a near-lethal amount of coffee — since Sieun’s hippocampus burned that phrase into his synaptic memory:
“We should break up.”
Just like that. Flat. Emotionless. Like their relationship was an old file being deleted from a desktop. Two years — gone with a few syllables and a shrug. And for what? A quick fuck at a party? Really?
“I think we should experience more things before settling down. Have a bit of fun, find ourselves before anything serious. You too, you know?”
Sieun’s jaw clenches.
Experience more things.
He should shove the experience up his ass. Really.
He can still hear the softness in Wooyoung’s voice, like he was being reasonable. Like this was Mr. Billy Flynn's solo in We Both Reached For The Gun. Throwing Sieun to the side like he hasn’t been enough to satisfy his ego, claiming they both should meet more people when he knew damn well Sieun would never do it. And then, once his dick got wet enough, get back together.
What did Wooyoung expect him to do? Smile? Nod? Offer a handshake?
“Oh, okay. Good luck with finding yourself, Wooyoung! No hard feelings. I’ll just go fuck off since you don't need me anymore, and crawl back once you’re done. Totally manageable."
Absolutely not.
Wooyoung should’ve known better. Should’ve remembered who he was dating.
Sieun is petty.
He is. He won't deny it.
Sharp. Calculated. The kind of petty that doesn’t forget.
He knows it is not a good trait to have. He knows being petty usually comes with selfishness and greed. And yeah, Sieun is selfish and greedy as well. So what?
He likes being in control. It makes him feel safe. Control is the only variable that calms the flood of stimuli and chaos in his mind. If he can't control the system, he dissects it. Understands it. Rewrites it. Owns it.
He doesn't care if he has to push and piss a few people to make it happen. He will not accept a different response other than the variables he predicted.
It's been like that since he was a kid, when he pulled a girl by the hair after she sabotaged him during their class quiz competition, by stepping on his feet so she could get the button first.
It’s still like that in college, when he writes and prepares a group presentation entirely on his own because he knows his colleagues won't match his standards. He's okay with just giving them the resume of what each one will present, as long as they at least fulfill their part by presenting it decently.
Wooyoung was supposed to be predictable. Safe. Sieun had already memorized his pattern of behaviour; most of the time, he already knew what the boy wanted before he even spoke.
But this? This is bullshit.
Unpredictable, unrecognizable, rogue behaviour.
So, no. He won't just move on and let Wooyoung have his cake and eat it, dumping him just like that to go fuck around like a fucking dog. Not when Sieun had spent two whole years of biofeedback regulation in his presence. When Sieun prioritized him over his lab reports, sacrificing study blocks to support his matches, going to stupid parties he didn't even enjoy, just to spend time with him.
And especially not after being put into a spotlight he had never asked for, just to be left alone, humiliated.
Because Sieun had not been a popular kid during freshman year. Far from it.
He did have a reputation — he was known for his grades and intelligence even in his first year. Some feared him because of his cold demeanor, some thought he was kind of mean, rude, and arrogant. Sieun didn't really care about that.
Wooyoung, however, was definitely a golden flower on the campus. A star MMA athlete, with surprisingly high grades and a charming, cocky personality that hooked anyone lucky to catch him strolling by. He was campus royalty.
And when word got out that he was dating the infamous “Ice Princess” — cold, blunt, top of the neuroscience department — people talked.
How did they meet? When did they start talking? How did Wooyoung melt Sieun into dating him? Does Yeon Sieun actually have a heart after all?
His name was on the mouths of people he had never even seen before.
Before he knew it, he was being dragged to post-match parties, being kissed in public, being bragged about. He wasn't that into PDA, but he knew Wooyoung was a touchy person, and he liked to show off. So he let him.
Wooyoung had access to a Sieun that no one else had. He got to know Sieun like no one else.
The disorganized mess of plush Sanrio characters he kept on his dorm bed. The hours he could spend geeking out about axonal conduction velocity or the electrophysiology of a brain. The way his breath would hitch mid-kiss. The way he begged, and sighed, and moaned when Wooyoung hit the right spot, and how clingy he would get after sex. These were all restricted for him to see.
And if Wooyoung wanted to throw all of that away like it meant nothing, that's fine. But, not on the back of his name.
Sieun’s reputation was tolerable before — aloof, maybe harsh, but academically untouchable. Now? Now he’s a rejected ice queen. A gossip headline. A sad story.
And Wooyoung… Wooyoung is a fucking liar. Because it’s been only a week, and he already has his hands laced with a new, prettier, shinier boyfriend. Grinning at parties. Posting smiling selfies. Kissing mid-match like it’s a damn K-drama finale.
It's humiliating. Everyone knew, and everyone looked at Sieun like he was about to throw a pity party.
If there's something Sieun is going to throw, it's hands.
He's fighting the need to punch a wall.
Fighting the storm inside his chest that feels too illogical for someone who understands exactly how emotion works.
He knows the science. The brain registers heartbreak in the same way it registers physical pain. The anterior cingulate cortex lights up — the same region that reacts when you burn your hand or break a bone. The body doesn’t even know the difference.
It’s chemical.
It only pisses him off more.
The brain is just chemistry. Love is just chemistry. All of this is just a stupid chemical imbalance.
He’ll fix it.
"Yeon Sieun."
The voice jolts him. His head snaps up.
The classroom is empty. Only the professor remains, watching him with a mix of tiredness and exasperation. “Do you need something?”
Sieun blinks, once. Twice. "No, Mr. Yoon. Sorry. I spaced out."
He quickly gathers his belongings, throwing everything messily into his backpack and swinging it across his shoulder. He bows politely before leaving the class hurriedly.
Kang Wooyoung.
Not happy with messing up his love life, now is getting in the way of his studies too. This was so not going to stay like this.
When he reaches the cafeteria, Juntae’s already at the table, rearranging the grains on his tray like he’s conducting a study of his own. Sieun drops into the chair with a sigh that’s more like a growl.
“Tough day?” Juntae asks.
“Tough week, ” Sieun mutters. He shoves three grains of rice into his mouth like it's a full meal. “I’m so fucking tired of people staring like I’m some kicked puppy.”
Juntae glances around. There are eyes on them. Whispers. Curiosity.
“They’ll get tired eventually.”
But they didn't.
Firstly, because the universe apparently hates him. Because he keeps seeing them.
He crosses paths with Wooyoung one too many times for someone who's been so cautiously avoiding every single place he used to hang around.
And secondly, Wooyoung is rubbing salt on the wound. He's showing off his new boyfriend — who, he’s come to learn, is not even an actual boyfriend — like he's the shiniest trophy one could achieve, and nothing could ever be better than him. It makes Sieun's blood boil. Wooyoung used to look at him like that. He used to be the prize everyone so desperately wanted, but only Wooyoung had.
The gossip doesn't stop. It grows. It becomes louder at every party Sieun skips and they attend together, at every kiss Wooyoung throws after knocking out an opponent a match. Every action of the couple leads to comparisons, to whispers, and Sieun is sick of it.
He wants Wooyoung to pay for it. He wants to make him suffer.
He wants to show that he, too, can have fun with other people. He doesn’t need Wooyoung, never has. He wants Wooyoung on his knees, begging to be taken back, begging for a second chance, only to have the pleasure of uttering a simple no.
He just doesn't know how to.
How is he going to have Wooyoung crawling back when he’s probably shoving his tongue in someone else’s mouth at this exact minute?
"You just need to make him jealous," Juntae offers, while scribbling in his notebook. "He's still a possessive person, and he probably still likes you, even if you're not together anymore. He’s just a dick."
"Mmh."
They're in the library, studying for their respective exams, and there's almost a visible smoke coming from Sieun's ears from how much he's thinking. Except, it's not productive thinking. He's not thinking about molecular neuroscience like he should because it's his next exam. Instead, his eyes constantly trail to the couple sitting in the far corner, in between some bookshelves, and the topic flooding his mind is how to trigger someone's neurological mechanism of pain and stress.
Seeing happy couples around, acting all cute and in love — he started to hate that view. Especially in the library. It was his refuge. Now it’s contaminated everywhere he looks.
He grips his pen too tightly. It snaps in half. Ink stains the page like blood.
Juntae jumps. “Sieun-ah…”
“I’m fine,” he says through clenched teeth.
"Maybe just, I don't know, punch him in the face. It would be pretty humiliating for him."
He could.
If he was fast enough to hit Wooyoung before he could react — hit him in one go, unexpectedly — he could absolutely punch him in the face. His nose would crack easy. He knows the weakest cartilage points.
But no.
That's not how he wants to hurt Wooyoung.
Physical pain is primitive. It fades. Bruises heal.
No, he wants psychological warfare. He wants to manipulate the same systems Wooyoung used to love in him. He wants regret. Sleeplessness. Longing. He wants to infect his thoughts like an untraceable virus.
And just then, a thought crosses his mind.
"Juntae, you're a genius."
“I am? I mean, I did get the top grade in BioChem 301, but—”
But Sieun’s gone. Already plotting.
Because if there's something Wooyoung is, it's possessive. Even if he’s wetting his dick around campus, even if he said Sieun should do the same, he doesn’t want Sieun to. He only said it to sound less selfish, because he knows it’s not the type of thing Sieun would do. Because he knows Sieun will simply retreat back to his shell while he gets to “experience things.”
But if Sieun decides to also have a piece of that cake, he just knows Wooyoung’s ego won't allow him to be unbothered. So, he’ll do it.
He’ll make Wooyoung watch him flirt, laugh, kiss, glow.
It can't be that hard, right? He knows how to read people, how to analyze them and predict their next move. He can use that to his advantage.
Yeah, Sieun can do this.
ಇ.
Sieun can't do this.
He's worse at flirting than he ever thought possible.
People just don't seem to understand his intentions.
Whenever he tries to approach someone, they act like Sieun has a gun pressed to their head. Every time he tries texting someone, the receiving end tells him he's got the wrong number and just stops replying.
Maybe "Hi. I saw you looking at me at the cafeteria." wasn't the best way to start a conversation.
He's too bad at this.
He sounds too cold, too robotic. Too him.
If this continues, he'll just end up embarrassing himself even further, when people realize his intentions and conclude that he is, in fact, a loser who was just lucky to have Wooyoung's attention.
He's not a loser. He just doesn't excel in social interactions.
Reading people is easy, in theory.
Sieun can tell you exactly how the brain responds to attraction. The cascade of chemical signals that spark when someone laughs at your joke, or brushes your arm, or holds your gaze just long enough. He’s studied the way dopamine spikes in the reward system — the ventral tegmental area lights up like fireworks. Oxytocin strengthens emotional bonds. Serotonin drops explain the anxiety that makes people obsess. Every crush is just a brain glitch with a hormonal soundtrack.
He understands all of it.
On paper.
But real people aren’t lab rats or textbooks. They're much more complex.
You can’t graph someone's attention span in a crowded room. You can’t measure eye dilation when they fake a smile. There’s no neat equation for knowing if someone’s flirting or just being polite.
Flirting, he’s realized, is not about logic. It’s improv. It's performance. It’s subtext layered over body language, layered over tone, layered over expectations that shift based on a thousand invisible factors — timing, history, mood, ego, instinct.
There are too many variables.
In a Petri dish, cells behave. In his head, systems are clean. Predictable.
But in real life?
People say things they don’t mean. Laugh when they’re uncomfortable. Lie to be nice. Hide when they’re scared.
You can’t model that. You can't trust that.
And Sieun — for all his intelligence — doesn’t know how to navigate it. He doesn't know how to start a conversation with someone he's interested in. He doesn’t know the right ratio of eye contact to maintain without it feeling weird. He doesn’t know what words to use, what tone makes someone feel safe but not disinterested, bold but not creepy.
And he doesn't know how to read people's intentions. When they say things they don't mean literally, the innuendos, the sarcasm, the I said it with the most serious tone and face you've ever seen but you should've known I wasn't being serious. He can't tell how many times he's been told to read the room. He can't. He doesn't know how.
He knows how to read a brain scan, but he has no idea how to read a face.
So no — he doesn’t know how to flirt.
He spent his whole life just reciprocating everyone with disinterest because he can't read in between the lines. And he'd rather just reject anything that comes his way than fall for someone who was just pranking him.
Wooyoung was different because he was easy to read. He carried his emotions — even when they weren't nice — on his face. Sieun felt safe.
And now, he's trying to break Wooyoung’s heart by doing something he doesn't even know how to start.
Sieun doesn't deal well with failure, nor with median performance.
He only does excellence.
He studies and works and doesn't sleep properly until he masters whatever he's trying to do.
He wants to be good at it.
But youtube videos and wikihows do not serve him what he needs. What he needs is professional help. He nees lessons.
Sieun has someone in mind.
He's been staring at his phone for over ten minutes now.
There's a specific contact on the screen and a text he hasn't been able to send yet. He's overthinking.
His thumb hovers over the send button, but he doesn't click on it.
Is he actually going to do this? Is he really that desperate?
No.
But...
He doesn't know what to do. He needs someone who knows this kind of stuff, someone who can teach him. Someone who won't judge him.
9:02 AM - SIEUN:
Remember that favor you owe me?
He closes his phone as soon as he sends the message, biting his nails nervously. This is even more humiliating than whatever he's been doing these past weeks. He's asking to be made fun of.
The notification on his phone arrives only a few minutes later.
9:10 AM - AHN SUHO:
of course
what do you need?
9:11 AM - SIEUN:
Can we meet?
I'd rather we talk in person.
9:11 AM - AHN SUHO:
sure
I have class till 10
9:12 AM - AHN SUHO:
we can go to that café in your building
9:13 AM - SIEUN:
Ok.
I'll arrive around 10:30.
He hesitates before adding the last message:
9:14 AM - SIEUN:
Thank you.
ಇ.
When Sieun walks into the familiar café, Suho is already sitting at a table near the window, sipping on his coffee. There's a plate with cake and a cup of iced matcha placed across from him.
Sieun only sighs and gathers strength before finally making his way toward the boy. He sits down, greeting Suho, who offers a comfortable smile and shoves the food in his direction.
"Here. Eat."
He raises his eyebrow. "You didn't have to."
"I know. I just guessed you might be hungry. All the science must burn some brain cells."
He is right, Sieun is hungry. The cake is the same one he used to order every time they met to study. Sieun never gets tired of it. He almost sighs in pleasure when he tastes the chocolate on his tongue. It's so good.
When he opens his eyes again, Suho is staring.
"...Do you want some?"
He shakes his head with a smile. "Already ate."
Sieun nods. He continues chewing silently, and Suho leans back into his seat. "So," he eyes Sieun curiously, "What did you want to talk about?"
Sieun cleans his throat a bit, drinking from his cup to down the food, then, carefully. "You owe me a favor."
Suho's smile grows. "Yeah, we already established that. You saved my ass last year, and in return, I owe you my firstborn child, my bank account, and probably a kidney..."
Sieun rolls his eyes at the dramatic comment.
He did save Suho's ass, but their deal wasn't like that.
Last year, when Suho was about to fail Biomechanics, he begged Sieun to tutor him on the subject.
The answer was obvious: no.
Sieun doesn't tutor. He doesn't teach. He doesn't waste his time with people who don't put effort and then ask for a magic class to learn what they ignored the entire semester.
Usually, people tried to bribe him with money. Sometimes, they would buy him food. Sieun has denied some damn good offers, just for the sake of his own pride. He wouldn't sell himself.
Suho hadn't even tried to bribe him, just begged him like a dog. It was the easiest no he's ever uttered.
Besides, Biomechanics wasn't even in his curriculum.
Sieun knew it, of course, he studied anything that might enlarge his knowledge and contribute to his understanding of the human body and brain. But he wasn't particularly an expert at it.
If anything, Juntae was the right person to tutor him. He majored in Biochemistry. They had Anatomy together in freshman year and then Pathology in sophomore year. They would have shared Biomechanics as well, but Juntae did the class in advance, so Suho was left alone. But not before infiltrating Juntae's poor little heart.
Juntae really liked Suho, for some reason. He wanted to help him in any way way he could, but he was already tutoring four people, and he didn't have space to fit Suho in.
"Please, Sieun-ah! He's a good guy, I swear he's trying really hard." He had heard that so many times before, but it was surprising to hear it from Juntae.
"If he were trying, he wouldn't be failing in the first place."
"He has a job in addition to class and baseball. He's trying with what he can..."
Juntae did his Puss in Boots stare with all his might, and Sieun almost gasped. He was trying to manipulate Sieun by looking cute? Fuck.
He was not Juntae-proof.
In the end, Sieun had caved.
"Fine," he said to Suho when they met at the café for the first time, "I'll tutor you, but you will owe me big time."
Suho almost kissed Sieun's foot while thanking him, and guaranteed that, whenever he needed something in the future, Suho would be glad to grant his wish.
Future being now.
But, Sieun doesn't really know how to ask.
Truth be told, he wasn't even sure if it would be a fair trade.
They did agree on a big favour, but was this too big?
The knock on the table cuts through Sieun's thoughts like a knife. Suho is still staring at him. "Stop thinking, just tell me."
Sieun bites his lips. He looks around, seeing if anyone is paying attention to them.
"You have to promise not to tell anyone."
“As a future medical professional, if you killed someone, I’m technically obligated to call the cops—”
"And you can't make fun of me."
Suho then blinks, slightly confused. "Okay..."
Sieun presses his head to his hands, which are propped on the table. He counts to three.
"Wooyoung and I have broken up."
"I know."
Simple. Matter-of-fact. Not even a second after.
Of course he knows, everyone knows. Sieun expected that.
"I need your help to make him jealous."
And then, silence. He looks up to see Suho staring at him, mouth slightly opened, eyebrows millimetrically raised. He can see Suho's lips twitch ever so slightly.
"Don't laugh."
"I'm not!" He raises his hands in defense. "I'm just surprised. I didn't see it coming."
Suho takes a sip from the coffee, calmly, then swirls his cup. The silence is killing Sieun. "So what, you want me to date you?"
Sieun immediately frowns. "What? That's not what I said."
"You said you need my help to make him jealous."
"Yes." He nods.
Suho waits for Sieun to keep going, but he doesn't. His intentions are clear, aren't they?
"How... do you plan on making him jealous?"
God, Suho was going to make him say it?
Sieun looks away. He feels the heat flooding his cheeks and he can't help but bite his lips nervously. This is so embarrassing. Why did he ever think it was a good idea?
"You know what, forget I said anything." He rises from his seat, but Suho's tight grip on his wrists keeps him from moving away.
"Hey, it's okay." His eyes are deep into Sieun's, like he's seeing Sieun's entire soul. It makes him sick. "Tell me what you have in mind."
And for some reason, Sieun finds himself sitting back down.
"I wanted you to teach me to... flirt." His eyes are trained on the table, unable to meet Suho's. “…You're good at that stuff. Parties, kissing people, looking cool or whatever. I want him to see me having fun. Without him.”
Suho nods, like it makes sense.
"Wah, Sieun-ah."
"Don't call me that." They're not close enough to me to be informal with each other.
Suho doesn't even mind the jab. "I didn't think you'd ever want to become like me."
"I don't, I'm not—" Sieun gulps. "I don't want to fuck around. I don't do that. I have self-preservation."
Suho smirks. Sieun realizes he might've just insulted Suho, but it's true.
Fucking around with whoever is available, not even knowing what else they have been doing before. Do they even use protection? Sieun bets most of them don't, which makes it even more gross. The number of STDs walking around campus must be crazy high.
Gross.
But Suho still smiles. "Okay, I'll help you." Sieun almost smiles back. "But,"
That makes Sieun frown. But?
"You can't say 'but'. You owe me."
Suho laughs. "You're cute," he keeps going anyway. "But, you have let me call you comfortably."
Sieun rolls his eyes.
"C'mon, Sieun. We'll be pretty intimate friends, I'll be sharing all of my secrets with you." He offers. "The least you could do is let us be actual friends."
Sieun bites his lips, considering.
It's not that much of a sacrifice. Sieun does like Suho — only a little bit.
He realized Juntae was right on their first session together. Suho does try, really hard. He's very smart and dedicated; he just needed someone to ground his mind so it wouldn't wander.
And, even though he is sort of fuckboyish, he's an overall nice guy. He never crossed the limits Sieun established, never tried to take advantage of him, and was — still is — very thoughtful, an example being the lunch that just made its way to Sieun's stomach.
He's a bit too flamboyant at times — too many jokes, too many (failed) attempts at making Sieun laugh — but Sieun is used to that. He got used to Wooyoung joking around all the time.
So, with a defeated sigh, he agrees.
"Happy to be at your service."
Suho watches as Sieun finishes the cake in silence, clearly processing their whole encounter and how this was even going to happen.
"So," Sieun is the first to speak up, once he finishes downing his matcha. "Are you just going to stare at me?"
Suho tilts his head. "What, you want me to start already? Now?"
Sieun shrugs. "I don't have anything to do now. You?"
Suho squints, but sets down his coffee. "Alright, flirt with me then.
The miserable look on Sieun's face must tell Suho exactly what he's thinking: What the hell are you saying?
"I need to see what you're doing so I can properly advise you." He playfully taps on Sieun's hands. "C'mon, just pretend I'm some random handsome guy, it's already half true, anyway." And then a wink.
Sieun had never seen Suho like this.
They had a clear line between them that was never crossed. Suho was careful and respectful around Sieun.
Now, he's acting cocky. He's getting comfortable. He's being careless in front of Sieun, and Sieun is not used to that.
The smug grin on his face. It tickles something in his brain, but he's not sure what.
"Um... Hi." Suho blinks at him, only nods slightly. "I've seen you before." At that, Suho scrunches his nose. "What? People say that."
"No, they don't. Plus, your tone was kind of threatening. I would be afraid of you. Try being nicer."
Sieun presses his eyes shut for a few seconds, trying to bury this embarrassment down in his stomach. "Can I have your number?"
Suho smirks. "Why do you want my number?"
"To report you to the police? To text, obviously."
"Yah! What the fuck?"
"Seriously, who would ask that?"
"A lot of people do! It's foreplay, people play dumb even if they know your intentions!"
"I don't want someone playing dumb."
Suho drops back into the chair with a grunt. "Yeon Sieun, wah, really." When he lowers his head to look at Sieun again, he's grinning in disbelief. "You can't be picky."
"I am."
"But you can't be. People already think you are arrogant as fuck, you're just confirming it to them. No one likes an arrogant person."
Sieun can only bite his tongue so as not to fight back. He is arrogant. He doesn't mind being seen as one. But the way Suho said it felt like an actual insult.
"I have to go."
Suho frowns instantly. "You said you were free."
"I changed my mind."
"Sieun-ah." Sieun almost winced at the sound. Gosh, he's going to have to get used to that. "Sieun-ah, you can't run from criticism if you want to get better."
"I know." He does. He truly does. "I just... need to prepare myself, mentally. It's a lot."
Suho's expression finally softens. "M'kay. Text me if you need anything."
"Okay."
He won't.