EXTRA CREDIT ──── choi soobin.
── .✦ (🥥) who would've thought that a late night tutoring sesson with the schools biggest nerd, soobin, turned into a night even more exciting. turns out, he has an even bigger surprise than his brain.
pairing: big dick virgin!soobin x fem!reader
word count: 4.8k
"content warning 18+ [ MDNI! ], switch!soobin, fem reader, big dick virgin!soobin, nerdy dirty talk, he researched ab sex, nerd!soobin, unprotected sex, multiple orgasms, riding, creampie, aftercare”
you invited him over because you were failing math.
there wasn’t anything romantic or flirtatious about it at first — just a silent cry for help written in red marker across your test papers, the kind of desperate slope only someone like choi soobin could pull you from.
he was quiet in class, but always had the right answers. you’d never seen him speak above a whisper, never seen him look anyone in the eye for more than a second, and yet he always left the lecture room with perfectly annotated notes and the air of someone who carried his self-worth in decimal points and weighted averages.
so you messaged him one night — a simple, “can u tutor me?” — and he agreed with alarming speed.
showed up three days later at your apartment like a boy heading into battle, papers in one hand and a mechanical pencil tucked behind his ear, even though you weren’t going to a classroom.
he barely spoke as he stepped inside, his oversized hoodie swallowing his frame and his backpack clutched so tightly in his hand you worried the strap might snap.
“hi,” he said, voice soft, and then added, “i brought… some topic breakdowns. just what i thought would be most helpful.”
you took the stack of papers from him, letting your fingers brush his as you did — just enough to make him freeze.
“thanks, soobin. you’re a lifesaver.”
“it’s no problem,” he replied, though his voice cracked a little halfway through, and he cleared his throat like it embarrassed him.
he stood awkwardly in the middle of your room until you gestured toward the bed. “we can work there. my desk’s a mess right now.”
he nodded too quickly, walking over with that stiff, careful posture that always made him look like he didn’t know what to do with his limbs.
he perched on the very edge of the mattress, knees pressed together, bag in his lap like a shield.
you were already sprawled out beside him, legs crossed, chin in your hand, flipping lazily through the printouts he brought. he’d highlighted things in different colors — pink for formulas, green for common mistakes, blue for examples — and even used sticky tabs to mark each section.
you smiled a little. “damn. you really prepped for this, huh?”
“i didn’t want to waste your time,” he said, not meeting your eyes. “i mean, you’re busy. i figured i should… y’know. make it count.”
your gaze lingered on his profile for a second — the soft curve of his cheek, the glasses sliding slightly down his nose, the way his lashes caught the light like they didn’t belong on a boy. “you’re cute when you’re nervous,” you said.
his ears flushed pink immediately, and he opened his mouth to say something but couldn’t find the words.
instead, he ducked his head and pulled out a worksheet from his bag, mumbling something about “starting with derivatives.”
for a while, you worked. or at least, you tried to. he was focused, explaining things in his soft, careful voice, gesturing with a pen as he talked.
but the more you listened, the less you heard — your brain slowly replacing the numbers and variables with the warm hum of his voice, the gentle slope of his mouth, the way his fingers tapped the edge of the paper like he needed the rhythm to keep from spiraling.
you weren’t sure when it shifted.
maybe it was when he leaned in to correct your equation, his shoulder brushing yours, and didn’t pull away. maybe it was when your knees touched under the blankets, and neither of you moved. maybe it was the way the air felt heavier now — less like study session, more like waiting for something to happen.
soobin must’ve felt it too. his words started stumbling. he explained one formula three times and still got lost halfway through, cheeks flushed, pupils dilated.
his hand hovered a little too long when he passed you the pen. when your thighs pressed together again, he sucked in a breath and didn’t let it out for four seconds.
you turned slightly to face him, setting your notes aside. the room was quiet now.
just the soft tick of the wall clock and the low buzz of tension coiling between you like a wire being pulled tighter and tighter.
he was looking at your mouth.
you didn’t speak. neither did he. the moment didn’t need narration — it just hung there, charged, inevitable.
and then it snapped.
your lips met his like gravity had pulled them there — sudden, unspoken, too natural to be a mistake. his breath hitched immediately, eyes fluttering shut like a reflex.
he tasted like vanilla and nerves, soft and shaky against your mouth, and when your hand came up to cup his cheek, he made a sound, barely audible, like the beginning of a whimper, and leaned into it like he’d been waiting all night.
you deepened the kiss slowly, letting it unfold, letting him adjust. he responded with this aching softness, fumbling but eager, his fingers curling into the bedsheets like he didn’t trust himself to touch you yet.
he wasn’t practiced, his lips moved like he was still learning. but he kissed you like he meant it. like he felt it.
you pulled back just slightly, breath tangled with his, your foreheads nearly touching.
his eyes stayed shut and he swallowed hard. “is this okay?” he whispered.
you nodded, brushing your thumb over his flushed cheek. “mmhm.”
he opened his eyes then, wide and vulnerable, and you could feel how hard he was trying to stay calm. how the tension in his shoulders hadn’t fully left. like he was waiting for the next step but terrified to ask for it.
but you didn’t rush. you just leaned in again, slower this time, and kissed him like there was nothing else you wanted to do tonight.
and this time, he kissed you back like he believed it.
but the kiss had unraveled something in both him and you.
he was still leaning into you like he hadn’t realized it was over, lips parted, breath catching at the edges, glasses slightly fogged from how close you’d been. you could see the color bleeding up his neck in slow-motion, creeping past his collar like his whole body was flushing from the inside out. he looked dazed. pink. utterly stunned.
you wondered, for a moment, if he’d ever been touched like this before.
but then he blinked, slow and heavy, and something in him cracked open.
he kissed you again, unsure, but full of need. like he’d been holding it back for too long. his hand twitched, then moved up — resting on your waist like he was afraid he’d break something, fingers brushing the hem of your shirt.
you climbed into his lap without thinking. not rushed. not performative. just a natural shift, a quiet surrender to gravity and tension and everything that had been simmering between you all evening.
he made a noise, sharp and startled when your weight settled on him, and his hands flew to your hips like instinct.
you could feel him underneath you already, half-hard and growing fast, and the realization sent a low throb through your stomach.
“fuck,” he whispered before he could stop himself.
you stilled. “hm?”
he looked horrified. “n-no, i mean— i wasn’t— that wasn’t—”
you tilted your head, amusement curling at your lips. “you okay, soobin?”
his throat bobbed. he didn’t answer. just stared at you like you were something holy and terrifying.
then, voice barely a whisper: “i’ve never done this before.”
you blinked. “like… never?”
he shook his head. “n-no. not even close.”
you felt your expression soften, and you leaned in to kiss him again, gentler this time. “you want to stop?”
he hesitated — not with fear, but with something more fragile. like he was trying to trust himself to speak.
“…no. i want to—” he paused, breath shaky. “i want to. just— it’s my first time, not my first time… knowing.”
you blinked again and chuckled slightly. “what?”
he turned bright red. “i… studied.”
you stared.
he flailed. “not in a weird way! i just— i didn’t want to be bad at it. s-so i read stuff. books. forums. diagrams— i even watched videos sometimes but only for like— like educational purposes—”
you blinked again. slowly. “…so you watched porn. like, for science.”
“i wanted to take notes,” he said, sounding genuinely defensive.
you laughed. couldn’t help it. he looked so earnest about it — like he’d genuinely sat down with a browser tab open and a pen in his hand, analyzing thrust angles.
“you’re unreal,” you said softly.
“i just didn’t want to disappoint anyone,” he mumbled, eyes downcast.
you reached down and took his hand, guiding it under your shirt. he froze, mouth open slightly, and his fingertips trembled against the skin of your waist.
“you won’t,” you promised. “you’re already not.”
his breath hitched. he looked up at you like you’d just rewritten the rules of the universe.
you started to grind your hips, slowly, experimentally — not enough to overwhelm, just enough for friction.
just enough for your shorts to tug against his sweats and for the growing heat between you to become unmistakable.
and god, he was big.
you could feel it — not in a vague, flattering way, but in a real, holy-shit-how-are-you-expected-to-fit-inside-me way.
every roll of your hips brought him further into focus, your body reacting before your brain could even catch up. he was so hard already, twitching beneath you, and he hadn’t even touched you properly yet.
“s–shit,” he gasped, eyebrows scrunched. “this— this isn’t in the articles—”
you snorted. “what, grinding?”
“n-no— i mean— yes, but not— not like this—”
you kissed him again, harder this time, swallowing the way his voice caught in his throat. your hands pushed his hoodie up slowly, palms skimming over warm skin, and he shivered when you reached his chest.
he looked like he didn’t know what to do with himself. like every second of contact was tripping a wire in his system.
you whispered against his lips, “you’re gonna let me ride you, right?”
his eyes rolled back so fast it was almost funny. “god— y-yeah. anything. anything you want.”
you reached between you, slipping your hand under his waistband — and what you found made your breath stutter.
he was thick. heavy. the kind of size that made your thighs clench just imagining it. no wonder he’d studied. no wonder he was scared.
you looked at him, slightly stunned. “jesus christ, soobin.”
he blinked, confused. “w-what? is it— is it weird? i read that some people have curve—”
you cut him off with a kiss, messy and open-mouthed, and his hands clutched at your waist like he was trying not to fall off the earth.
“it’s big,” you muttered. “like… really fucking big.”
he made a sound you couldn’t describe — somewhere between a choke and a moan.
you stripped slow, teasing, sliding your shirt off and watching his eyes widen as more skin revealed itself.
he stared like he wasn’t sure if he was allowed to look. like he wanted to memorize it but felt guilty for trying.
you helped him out of his clothes next, pulling his hoodie over his head and tugging his sweats down far enough for him to spring free.
he gasped when the air hit him. flushed deep pink from tip to base. twitching slightly in time with his heartbeat.
and yeah. huge.
he tried to say something, but it came out garbled. you didn’t let him speak — just kissed him again, sweeter this time, pressing your body against his until he was whining into your mouth.
“lie back,” you whispered, and he did.
you climbed on top of him slowly, positioning yourself, and when the tip nudged against you, both of you gasped.
you took your time, letting him feel every inch of you — the stretch, the slide, the warmth — and his jaw dropped like it was all short-circuiting him.
“ohmygod,” he moaned, hands flying to your thighs. “ohmygod, it’s so warm— it’s— fuck—”
you bottomed out and paused, letting him breathe. he was gripping you like he was afraid he’d float away, eyes glassy, hips twitching up just barely.
“you okay?” you whispered, brushing his sweaty hair from his face.
he nodded, but he looked wrecked already.
“i-it’s so much,” he choked out. “i d-didn’t think it’d feel this good— i thought— i thought i’d last longer—”
you started moving, and he whimpered.
“oh— oh fuck—” he cried, head falling back against the pillow. “you’re s-so— it’s too good— oh god— i’m gonna— i’m—”
you weren’t even bouncing yet. just rolling your hips, slow and deep, letting his cock drag against every inch of your walls. his eyes fluttered, his chest heaved, and he let out a sound that didn’t even sound human.
“such a good boy,” you whispered, to which he moaned in response. the prettiest noises leaving his mouth as you praised him.
he couldn’t stop shaking underneath you. soobin was all heat and trembling muscle, wide eyes flickering open only to shut again in dazed desperation.
his chest heaved with every shallow breath, slick with sweat, lips parted in a silent plea as your hips rolled down again — slow, deliberate, like you were memorizing the way he stretched you open.
his hands had settled at your waist, not gripping, not guiding — just holding, fingers splayed across your skin like he didn’t want to forget the shape of you. like he wasn’t sure this was real.
every time your cunt dragged down his cock, his stomach fluttered, tightening like a wire being wound tighter and tighter with no end in sight.
he was deep. impossibly so. every inch of him filled you, pressed inside with this perfect fullness that made your vision blur. the curve of his cock nudged something devastating with each movement, and yet the stretch never dulled — not even as your walls grew slicker, your legs trembling from the slow pace.
you rode him with patience. not because you needed to go slow — but because he looked so wrecked.
his eyes glassy, his thighs twitching, mouth caught in a half-moan that never made it out. his expression was nothing short of reverent. overwhelmed. ruined.
you leaned over him, skin sliding against his as your hands braced at either side of his chest. the shift made your angle deeper, pulled a broken sound from his throat that made your core throb.
he tried to lift his hips, just a little, just to chase the feeling, but he couldn’t get the rhythm right, too stunned, too overstimulated, too caught up in the sheer reality of you.
the head of his cock dragged against your walls again, and your mouth fell open with a gasp — because he filled every inch, every curve, as if he was shaped for you alone. he was pulsing inside you already, and you hadn’t even given him permission to move yet.
his hands twitched, your body ached for more, and so you let him.
you shifted, just barely — lifting your hips until only the thick head remained inside you, holding there for a breathless second, watching his jaw slacken as if he’d lost something vital — and then you dropped down again, full weight, taking him all the way in one smooth thrust.
his back arched.
the sound that broke from him was nothing short of guttural — low and soft and strangled at the edges, like he didn’t know what to do with the sensation.
“mmh, i-it… it feels so good… don’t stop… please”
his fingers finally tightened on your hips, not hard, just grounding — and you felt him thrust up.
it was shaky. clumsy. but the strength behind it was unmistakable. he met your next roll with a sharp buck of his hips, and it landed deep, sudden, deliciously raw. your breath caught. his face contorted, eyes fluttering closed, lips trembling.
he did it again. and again.
beneath you, soobin moved like he didn’t even know he could. the soft whimpering boy who’d watched porn for research was gone — replaced by something unfiltered, frantic.
he thrust up into you with so much need, so much pure instinct, that you nearly collapsed against his chest.
he was so warm. so deep. every time you sank back down on his cock, it filled you to the hilt. every motion sending waves of heat through your spine, your stomach, your lungs.
you clenched around him without meaning to — too full, too sensitive — and he gasped like he’d been punched, arms tightening around your waist. he sounded like he was breaking. like it was too much.
you rolled your hips down hard, once, and he cried out.
not loud. not dramatic. just this fragile, broken sob of pleasure that slipped out past gritted teeth as he tried to keep fucking you through it. tried to keep his pace even as his body started failing him.
he was close. you could feel it. his whole body trembling beneath you, stomach fluttering, cock twitching deep inside like he was aching to let go.
“w-wait… im gonna cum… p-please… don’t stop…”you ground down harder, deeper, faster — and he fell apart.
his hips jolted once, then twice, then lost all rhythm. his cock pulsed violently inside you, and then you felt it — thick, hot, the warmth of him spilling into you as his body seized and shuddered.
he buried his face in your neck, arms clinging to you like a lifeline, thighs shaking uncontrollably beneath yours as he came.
every pulse of his cock pushed his cum deeper, filled you more, the mess gathering between your thighs like he couldn’t help it.
his breath hitched, his mouth opened against your skin, and then the tiniest sob escaped — cracked and soft and overwhelmed.
he was crying again.
you held him through it, rocking your hips just slightly to ease him through the aftershocks. he twitched inside you, whimpering, helpless beneath the weight of it all. his hands gripped you like you’d disappear.
his cock throbbed inside you, overstimulated and soaked in your slick, and he just kept whimpering.
you pulled back to look at him.
his eyes were glassy, unfocused. his cheeks damp. he looked like he’d been cracked open from the inside out.
you leaned in and kissed his forehead, then his cheek, then finally his lips — soft and slow, grounding him.
his voice was barely there. “i— i didn’t mean to—”
you shushed him. “you did perfect.”
his lashes fluttered. his arms loosened. his body finally relaxed beneath you, sinking into the mattress, flushed and tear-streaked and filled to the brim.
he looked at you again, and you held his cheek. “you wanna go again?” you said, brushing your thumb across his face, catching a tear that fell earlier.
he nodded slowly, and he was still inside you when he started to move again.
his cock hadn’t even softened fully—still thick, still flushed a deep pink at the base, still twitching inside you from the overstimulation, but now he was shifting, testing, thinking through the daze. and that was the moment you knew, he wasn’t done.
his breath still caught every time your walls clenched, but he was moving—hips subtly lifting, grinding into you in soft, sticky rolls. the cum from his first release had made everything slick, slippery, messy—your thighs wet, your inner walls coated.
he was still nestled so deep you could feel him twitch against your cervix, and when he pulled back a few inches, a broken gasp slipped from your lips.
he froze, like he didn’t expect that sound. you felt his hands tighten at your waist.
“…i wanna try something,” he whispered.
before you could ask, he pulled out with a soft squelch, and you both moaned at the loss. but he didn’t waste time—didn’t even stop to overthink it—he just reached for you and flipped you, slow but firm, until your cheek was pressed against the pillow and your back arched, hips raised just enough.
you turned to glance over your shoulder, heart thudding.
soobin was flushed all the way down to his chest, hair stuck to his forehead, lips pink and parted—but his eyes had sharpened. still soft. still shy. but there was something new there now.
something focused.
his hand settled on your lower back, then drifted down to your ass, squeezing once like he was testing a theory. when he spoke again, his voice was low. almost dazed. “theoretically… this angle should stimulate the anterior wall more consistently.”
you blinked.
“…are you quoting a textbook right now?”
he pushed back in without warning—one slow, gliding thrust, his cock stretching you open again with a wet slide—and you choked on your own breath.
the stretch burned now, fucked-out and sore, but god, he felt so full. the second his hips pressed flush to yours, you felt your arms go weak.
“yeah,” he whispered. “i read about this. from the back, hips raised… it’s supposed to— oh fuck—”
he started moving before he could finish the sentence.
his thrusts were deeper this time. not rough, not fast—intentional. heavy. every motion angled slightly upward, every roll of his hips hitting that same devastating spot, over and over again.
you realized—somewhere between gasping into the sheets and gripping the pillowcase like it might save you—that he meant to do that.
“feels… right?” he panted, voice breathless. “am i… hitting it right?”
you couldn’t speak. could barely even moan. your body was melting around him, dripping slick and cum with every push, your mind already fraying at the edges from how deep he was.
his cock dragged against your walls with obscene precision—too precise, like he was adjusting his angle mid-thrust to line up with your reactions.
every time your thighs trembled, he leaned in further. every time you gasped, he whispered a frantic, “there—like that?” and did it again.
“fuck,” you managed, voice hoarse. “you— god, you feel so fucking good—”
he moaned behind you, and then his fingers curled around your hips to pull you back onto him harder.
the pace stuttered for a moment, but when he found it again, it was relentless. sloppier now, louder. the wet slap of skin on skin filled the room, each thrust jostling you further up the bed.
“read once,” he gasped, “that the g-spot’s like… five centimeters in… angled toward the belly button—f-fuck, wait—”
he adjusted again, slightly upward, and this time you cried out, legs buckling beneath you.
“there,” he whispered. “t-there it is. fuck.”
your entire body clenched. he felt it, gasped again, and leaned over you. now his chest was against your back, his breath warm and fast against your ear, hips still pistoning into you as he pressed you down with the weight of his body.
“you’re so—tight,” he breathed. “s-so warm— i can’t— i c-can’t stop—”
you weren’t stopping him.
your brain had shut off halfway through his nerdy monologue, somewhere between “g-spot location” and “angle of friction”. all you knew now was the way his cock dragged against your walls, the obscene squelch of your mixed arousal leaking down your thighs, the sound of his voice trembling as he kept going, even as his rhythm began to falter.
you could feel him close again. his thrusts started to stutter—less controlled, more desperate.
every breath came out choked. his grip on your hips turned vice-like, and his weight pressed you harder into the mattress.
“g-gonna cum again,” he whimpered, voice cracking. “inside, please, i can’t— i want— fuck, please—”
you let him. you even tightened around him on purpose. and that broke him.
his hips slammed forward one final time—deep and hard, burying himself to the hilt—and then he snapped, groaning into your shoulder as he came again, harder this time.
hot and messy, cock twitching wildly as his cum spilled out in thick spurts, dripping back down your thighs with every shudder.
he didn’t move for a long moment. just panted against your neck, body trembling, arms around you like a blanket.
still buried deep, still twitching from the aftershocks, still too full of sensation to pull out.
you were shaking too. used. sore. stuffed.
he kissed the back of your shoulder, then your spine. slow, reverent.
“…did i do good?” he asked softly, voice hoarse and breathless.
you turned your head enough to look at him.
he was flushed. swollen. smiling—barely.
you cupped his cheek, pulled him down into a kiss, and let him melt into you again.
you didn’t move for a while.
your body felt… gelatinous. boneless. like you’d been poured out, reshaped, and forgotten on warm sheets.
your thighs were trembling, too slick to close properly, your breath still shallow as you stared blankly at the headboard, brain empty except for the faint memory of being absolutely ruined.
and behind you—still pressed close, still inside—you could feel him twitching softly. Soobin’s arm was curled around your waist, his forehead damp against your shoulder, and his chest rose and fell in uneven waves as he tried to catch his breath.
“…i think i broke you,” he whispered.
his voice was so soft, so tentative, that you let out a shaky laugh despite yourself.
“maybe just… a little,” you mumbled, voice hoarse.
he didn’t respond right away. just let out a breath that was almost a whimper, and very slowly, he pulled out.
the sound was obscene—wet and slow and too much. his cum spilled out in thick, creamy rivulets, already smeared down your inner thighs, soaking the backs of your legs and your sheets.
he groaned under his breath the second he saw it, like even looking was too much for his nervous system to handle.
“oh my god,” he said, eyes wide. “i—fuck, i didn’t mean to—there’s just—so much—”
you flopped onto your back with a wince and watched him sit up on shaky legs, completely naked, flushed red from head to toe, hair a mess. his dick was still red and slightly twitching, glistening at the tip from whatever hadn’t managed to stay inside you.
he scrambled for his hoodie, dragging it on clumsily and then half-tripping as he grabbed his backpack off the floor.
“d-don’t move,” he babbled. “i’ve got—uh—one sec—”
you blinked. “soobin… what are you doing.”
he held up a pack of wet wipes.
“…why do you have those?” you asked.
he looked mortified. “i-it’s for glasses! and, um. keyboard dust.”
but he was already kneeling between your legs, gingerly nudging them apart with the back of his hand.
his face flushed impossibly deeper at the sight—your swollen folds, the sheer amount of cum, the fact that he put it there.
you watched his throat bob as he took a breath and started cleaning you.
gently, carefully.
he touched you like you might break, using slow, soothing strokes, barely applying pressure.
when the wipe brushed over your entrance and another trail of cum spilled out, he made a tiny noise in his throat and mumbled, “oh my god—i’m so sorry—”
you couldn’t stop smiling, too wrecked to be shy, too full of affection to care. “you’re apologizing for fucking me now?”
“i-i just—i should’ve warned you. or slowed down. or—” he paused, looking deeply concerned, “—maybe done a few more warmup exercises—”
you reached out and grabbed his wrist, stopping the endless spiral of his thoughts. “soobin.”
he froze. eyes wide.
“you were perfect.”
he blinked, like you’d just told him he aced an exam he forgot to study for.
“…r-really?”
“really.” you tugged him closer. “come here.”
he climbed onto the bed clumsily and wrapped his arms around you.
you let your head rest on his shoulder, body melting into the warmth of him as his fingertips gently traced circles over your spine.
he pressed a soft kiss to your temple. then your cheek. then, with shaky hesitation, to your lips.
“…you feel okay?” he murmured against your mouth.
“sore,” you admitted. “but in a good way.”
his ears went pink. “i didn’t think it’d… i mean, you were so tight, and i thought—i mean, i calculated it before, but actually being inside—”
you laughed again, too tired to tease him. “soobin.”
he looked at you, dazed and flushed and in love with you, probably.
you kissed him again.
and this time, he smiled against your lips. soft. warm. nerdy.
“…can i write about this in my notes?” he asked suddenly, like he couldn’t help it.
and you burst out laughing.
