homework and heart | yeon sieun x neighbour!reader
summary: yeon sieun is just trying to get through a study session without losing his sanity, but his lifelong neighbor makes that impossible—armed with sarcasm, zero personal space boundaries, and a habit of falling asleep on his arm mid-math problem. they argue like enemies, act like friends, and care like something they won’t admit.
author's note: i just know sieun would treat his girl like a delicate flower. everything about him (apart from his psycho tendencies) screams gentleman. the reader is sort of a tsundere or something. wrote this while listening to [ My Love Mine All mine - Mitski] . requests
“your handwriting looks like a drunk spider fell in love with a pen,” she said, peering over si-eun’s shoulder.
si-eun didn’t glance up. “you’ve said that before.”
“yeah, and it hasn’t improved.”
“you’re here for math help, not calligraphy critique.”
“i’m here for the free heating,” she declared, collapsing onto his bed like it owed her rent. “your floor heating is elite. i feel like a warm croissant.”
si-eun exhaled through his nose. “you’re supposed to finish the worksheet i gave you.”
“you’re supposed to stop being a fun vacuum,” she shot back, flipping onto her stomach and burying her face in his pillow. “why do you smell like laundry detergent and sad?”
he ignored that. “that’s page two. the functions review.”
she groaned into the pillow, her voice muffled. “why are you like this?”
“efficient?”
“emotionally unbothered.”
“that’s not a flaw.”
“it is when your only reaction to my suffering is to hand me a pencil.”
she sat up and tossed said pencil at him. he caught it midair without even turning his head.
“show-off,” she muttered.
“you threw it with the force of a butterfly.”
“rude. accurate, but rude.”
they sat in silence for a moment—her pretending to work, him actually working—until she groaned again and fell dramatically across the table, narrowly missing his open notebook.
“i give up. i’m becoming a flower shop cashier. i’ll name the succulents and everything.”
“you hate plants.”
“they hate me first. it’s mutual.”
“finish number five.”
“no.”
sieun said her name.
“make me.”
he leaned back in his chair, expression flat. “do your homework.”
she leaned forward, matching his energy. “make me.”
their faces were inches apart now, eyes locked in a silent, petty standoff.
“childish,” he murmured.
“lifeless.”
“stubborn.”
“robotic.”
“you still haven’t moved.”
“you blinked first.”
“that’s not how this works.”
“says who?”
“says logic.”
she rolled her eyes and dramatically scribbled on the worksheet. “there. number five. happy?”
he checked it. “that’s number six.”
“i hate you.”
“good. now do five.”
she cursed under her breath, then muttered, “you better carry my backpack at my funeral.”
“you won’t need a backpack if you fail this class.”
“then you better carry my coffin. same energy.”
si-eun glanced at her, the faintest trace of a smile tugging at the corner of his mouth.
she caught it and pointed. “there. you smiled. admit you like me.”
“i smiled because you said something dumb.”
“same thing.”
they didn’t look at each other after that. not directly, anyway. but she was quietly doing question five, and si-eun casually slid a bag of her favorite snacks across the table like it didn’t mean anything.
like always.
she got up without warning and dropped beside his chair, her chin resting on his arm, body invading his space like it was natural law.
“you need a break,” she muttered.
“you’re distracting.”
“good.”
he didn’t pull away. just let her stay there, still scribbling notes while her cheek pressed against the sleeve of his hoodie.
“you’re going to smudge the ink,” he murmured.
she shrugged. “you’ll rewrite it for me anyway.”
“that’s not how this works.”
she smirked. “isn’t it?”
they stayed like that, the sound of pen on paper and her breathing settling into rhythm.
she, of course, fell asleep fifteen minutes later. head still leaning against his arm, mouth slightly open, clumsy as ever.
si-eun didn’t move.
he just kept writing with one hand, while the other lightly tugged the blanket from the bed to drape over her shoulders.
outside, the sky finally decided to rain.
inside, there was peace—chaotic, uneven, stubborn peace. the kind only the two of them could create. the kind that made sense even when nothing else did.
yeon si-eun if his friends overheard you and him doing it
i made this happen if y'all went camping haha. enjoy!!
gotak called si-eun's name from across the campfire and asked, "yo, what were you and [name] doing in the tent last night? we heard some noises." we, of course, as in he, baku, and jun-tae, who shared a tent of their own. baku chimed in, "it didn't sound right."
that would've been hilarious if you weren't mortified.
si-eun perked up, eyes slightly wider than before at the acknowledgment. "huh?" you saw him flush slightly as baku clarified once more, "you got lucky last night, didn't you. si-eun-a."
you recalled all about last night; his lips, the way he moved, and how it was all thanks to your cracking open his shell. at the thought that he was the lucky one, you softened up a bit behind your poker face.
jun-tae wasn't smiling but you could tell it was an effect of restraint. si-eun's mouth opened a bit, but he held back and looked ahead at the ground before back up at baku. "it isn't like that," he lied, eyes back on his friends with innocence that somehow also wasn't a lie. but when you touched him, his heartbeat was faster, and you could feel it in his skin. you on the other hand, previously and sufficiently flustered, ended up bursting out laughing. his friends meant no harm, but you still had to shush them, as si-eun had entered a state of not knowing how to escape these accusations. he did in fact get lucky last night, and he wasn't a good enough liar to hide it.
you raised your index finger to your lips, gesturing to the group. "shh!! si-eun has a pen on him."
the laughter died down, and baku and gotak began to talk amongst themselves, realizing how bad it could be if they all got slaughtered this early into the friendship.
you took si-eun's hand fully now and he let you kiss his shoulder while he recovered from the callout.
💀 ABSOLUTELY NOT JUST THE TIP (THEY SAY IT, BUT THEY’RE LIARS)
Ahn Suho
Says "just the tip" with a straight face, but the second he's inside, he's balls deep. There's no halfway with Suho. He'll act like you imagined it when you call him out. Gaslight gatekeep girlboss behavior.
Shin Seokdae
Seokdae? He doesn’t even say "just the tip." He says "I’ll be gentle" and then jackhammers you like it’s a competition. There's no such thing as gentle or tip with him. He needs to ruin you every single time.
Oh Beomseok
Beomseok's the king of "I swear just a little, I’ll stop when you tell me" but you already know he's halfway in before the words finish leaving his mouth. Then he fake moans about how tight you are to distract you while he goes deeper. 🙄
⚡️ THINKS IT’S JUST THE TIP BUT GETS CARRIED AWAY
Yang Doohyeon
Doohyeon believes it’ll be just the tip... for like 2 seconds. Then his hands are on your hips and he’s pushing in more without realizing. He genuinely can’t help himself and apologizes after, but also does it again.
Kim Gilsoo
Gilsoo starts with the tip, but he's the type to tease you by grinding it inside you so deep that when you finally look down—oops—he’s all the way in. Pretends like it's your fault for "pulling him in."
💡 ACTUALLY JUST THE TIP KINGS (BUT TORTURE YOU WITH IT)
Yeon Si Eun (Gray Yeon)
Si Eun actually gives you just the tip... but he makes you beg for more. Cold-blooded. He keeps that shit right at the entrance, teasing you until you're crying for him to go deeper, and still? He'll smirk and pull back. Menace.
Park Hamin (Ben Park)
Ben’s too soft for all that chaos. He’ll really do just the tip if you ask him. But also he’s whining about how hard it is to stop. He’ll kiss your forehead while suffering inside. Baby boy behavior.
I’m so excited for this one!!😭 HAPPY 1k!! You definitely deserve it!!
+ IT'S SWEET
in which si-eun pretends to forget her birthday only to give her a surprise she always wanted.
+ YEON SI-EUN X READER
fluff
Birthdays were her favorite event of the year.
Not just her own everyone's. She loved the sparkle of candles, the chorus of voices singing too loudly, the messy frosting smudged on someone's lips. To her, birthdays were proof that life deserved to be celebrated. Even in their twenties, when most people waved them off as childish, she believed birthdays should feel magical.
The week leading up to her birthday was no different. She couldn't stop herself from humming with excitement. Between classes, she'd chatter about cakes she wanted to try, or how she loved when people went overboard with balloons and streamers. Her eyes would light up when she described surprises she had pulled for her friends in the past, her laughter soft and contagious.
Her friends smiled, amused by her enthusiasm. Some even asked her about her plans.
But every time she turned to Si Eun, hoping for even a flicker of recognition a teasing smirk, a dry comment, anything she found nothing.
He'd keep his head bent over his notes, pen scratching steadily.
No reaction.
No teasing.
Not even a faint acknowledgment.
It was strange. She knew he wasn't the most expressive, but this felt different. Almost deliberate.
When someone asked her what she wanted for her birthday, she noticed his knuckles tightening around his pen before he got up abruptly. "I'll get a drink," he muttered.
When she asked him directly if he had plans on her birthday, he didn't even pause. "I'll see," was all he said before changing the subject.
Her excitement dimmed with each passing day.
By the time her birthday finally arrived, she was exhausted from pretending not to care.
The morning sunlight spilled through her curtains in shades of gold, painting warmth across her phone screen. Messages pinged one after another friends sending emojis, cheerful reminders, promises of calls later.
But not him.
Not even a simple "happy birthday."
Her chest ached. She told herself not to expect anything. Si Eun wasn't the type. He didn't care for celebrations. Maybe she was foolish for hoping he'd be different with her. Still, it stung because somewhere deep down, she thought she mattered enough to him to make an exception.
The day dragged by in muted colors. She laughed with her friends at lunch, thanked them for their wishes, even blew out a candle on a small cupcake someone surprised her with. Outwardly, she smiled. Inwardly, she kept glancing toward the library doors, across the campus lawn, anywhere he might appear.
He never did.
By evening, she trudged back to her apartment, bag digging into her shoulder, steps heavy. The hallway was alive with muffled laughter and music behind closed doors other people enjoying their weekends. Her key clicked against the lock, her sigh spilling into the silence as she pushed her door open.
And froze.
The room glowed with warmth.
Golden fairy lights draped across the ceiling like stars. Balloons bobbed lazily in the corners, their ribbons curling. A cake sat neatly on the table, frosting glistening under the soft glow. Two small wrapped boxes sat beside it, careful and deliberate.
And standing in the middle of it all, awkward but waiting, was Yeon Si Eun.
Her breath caught. Her hands flew to her cheeks, laughter breaking out of her in disbelief. "You" she gasped, spinning toward him, "you really did all this?"
He shifted, shoulders tense, eyes fixed on her. "It's not much."
"Not much?" she squeaked, turning in a circle to take it all in again. "It's perfect!" Her smile stretched so wide it hurt, but she didn't care. Her chest felt like it was bursting, every ounce of the day's gloom scattering like dust.
He cleared his throat, moving to the table. With steady hands, he lit the candles one by one. The flames flickered golden against the fairy lights, dancing in the reflection of her wide eyes.
"Make a wish," he said quietly.
Her throat tightened. She clasped her hands, eyes squeezing shut. For a moment, she wished for nothing because everything she wanted was already standing in front of her. When she blew the candles out, the smoke curled into the air, and she giggled, clapping once like she was twelve again.
"Thank you," she whispered, voice trembling with happiness. "Really. This is the best surprise I've ever had."
His lips twitched not quite a smile, but the warmth in his gaze made her heart stumble.
They cut into the cake together, her hand brushing his as they steadied the knife. She gasped dramatically at the first slice, eyes sparkling as if it were a precious jewel. He slid it onto a plate, forked a small piece, and held it out to her.
"First bite," he said softly.
Her eyes widened. "You're feeding me?"
"…Isn't that what people do?"
She laughed, covering her mouth before leaning in, taking the bite. Sweet cream and soft sponge melted on her tongue, but sweeter still was the sight of him so serious, so intent, as though this simple act meant more than words could.
"Mmm!" she hummed, eyes fluttering closed. "So good!"
His brow twitched ever so slightly, the tiniest spark of amusement surfacing.
"Okay, your turn!" She scooped another piece and held it up. "Say 'ahh.'"
He didn't move. Just watched her, eyes unreadable.
"Si Eun," she scolded lightly, pouting. "Don't be difficult."
The pause stretched then slowly, he leaned closer. Instead of opening his mouth to the fork, his lips brushed hers. Soft, certain. Her breath hitched as he lingered just long enough to flick his tongue at the corner of her mouth, catching the smear of cream she hadn't noticed.
He pulled back with maddening calm. "…Hmm." His voice was low, teasing. "It's sweet."
Her jaw dropped. Heat rushed to her face as she dropped the fork with a clatter. "Y-You!" She buried her face in her hands, muffling her squeal. "Si Eun!"
For the first time, he actually smiled a rare, small curve of his lips, but warm enough to melt her insides.
"You should've seen your face," he said quietly.
She peeked at him through her fingers, cheeks blazing scarlet. "That's not fair!"
He didn't answer, only nudged her shoulder lightly, sliding the plate closer as if telling her to eat more. His gestures were simple, but layered with something deeper his way of showing affection, unpolished but real.
She giggled, the sound spilling out of her unchecked. He just watched her, steady and quiet, but there was no mistaking it now he was content.
And for the rest of the night, under the fairy lights, with cake crumbs scattered on the table and laughter tangled between them, she couldn't stop smiling.
Because this wasn't just a birthday.
It was proof she mattered to him.
And maybe just maybe it was the sweetest gift of all.
