NOT SO LITTLE ANYMORE | 𖥻 lee heeseung
「 brothers bsf heeseung x fem reader 」
genre ~ smut, fluff. big slow burn 5.0k
synopsis ᵎᵎ y/n has always known heeseung, her older brother’s best friend, who was a constant presence in her life growing up. now 20, despite her growing attraction to him, heeseung sticks to his rule of keeping her off-limits, honouring his promise to never cross the line of dating his best friend’s little sister. however, she’s no longer the little girl she once was.
warnings ᵎᵎ dry humping, hand job, nipple play, first time, p in v, unprotected sex (don’t do!), soft dom, profanity
the summer heat clings to the pavement outside, but the backyard is a sanctuary of cold drinks and loud music. the smell of charcoal and seared meat fills the air. jake stands by the grill, flipping burgers with an intensity that suggests he thinks he’s a professional chef. he laughs, shouting something about the secret seasoning to a group of his friends.
you float in the cool blue water of the pool, the chlorine stinging your eyes slightly. chaewon and haerin are beside you, their voices a blur of gossip and giggles. you can feel a gaze on you and you turn your head slowly.
heeseung sits on the edge of a lounge chair, a cold soda in his hand. he isn't talking to anyone. his eyes are locked on you, tracking the way the water beads on your shoulders. when you catch him, he doesn't look away immediately. his expression is unreadable, a mix of something heavy and hungry. then, he blinks and shifts his focus to his drink, a small, tight smile playing on his lips.
"he’s totally staring at you," chaewon whispers, splashing you.
"no he’s not," you reply, though your heart skips. "he’s just zoning out."
"like he wants to eat you alive?," haerin adds with a smirk.
you dive under the water to hide the blush creeping up your neck. heeseung has been a fixture in your life since you were a kid. he’s like an older brother, one you actually like, the one who taught you how to play video games and shared his snacks when jake was being a brat. but lately, the air between you two feels thick. it feels like a string stretched too tight, waiting for one of you to pull it.
── .✦
an hour later, the party is still humming, but you find heeseung in the kitchen. he’s holding his hand, a small piece of gauze pressed against a bleeding cut on his palm.
"what happened?" you ask, stepping closer.
"stupid can opener," he says. his voice is soft, a low rumble that vibrates in your chest. "jake told me to open the pineapple, and i think the pineapple won."
"let me see," you examined his hand before hissing in sympathy with furrowed eyebrows.
“come with me,” you gently lead him to your room, the only place where it is quiet.
you sit him down on the edge of the bed and fetch the first aid kit. you carefully peel back the bloodied gauze. the cut is shallow but jagged. you dab it with antiseptic, and he winces, his fingers twitching against the mattress.
"stop squirming," you murmur.
"it stings," he replies. you look up, and he’s already looking at you. he’s so close you can smell his cologne, something like vanilla and cedar. his eyes roam over your face, lingering on your lips before snapping back to your eyes. the room feels smaller. the sounds of the party downstairs fade into a distant hum.
"you look pretty today," he says.
your hand freezes. you search his face for a sign that he’s joking, but his gaze is steady. it’s an honest observation, stripped of the teasing he usually employs.
"you’re just being nice because i’m fixing your hand," you whisper.
he lets out a short, breathy laugh. he doesn't pull his hand away. instead, he let’s his fingers brush against your wrist.
"maybe i am," he says. "or maybe i’m just finally saying it."
the moment shatters when jake bangs on the door, yelling for heeseung to come help with the drinks. heeseung stands up quickly, the tension snapping like a rubber band. “thanks y/n,” he gives you a small, lingering look before disappearing into the hallway.
── .✦
a week later, the house is quieter. jake has left for a trip with his girlfriend, yunjin, leaving you alone with heeseung.
it starts with a low rumble that shakes the windows. then the sky turns a bruised purple, and the rain begins to hammer against the roof. a sudden, violent crack of thunder echoes through the house, and the lights flicker once, twice, and then vanish. the darkness is absolute. you freeze in your room, your breath coming in short, jagged gasps. thunder has always been your enemy. it feels like the world is breaking apart. another bolt of lightning illuminates the room in a ghostly white flash, followed immediately by a boom that makes you jump.
you stumble out of your room, your hands grazing the walls. you find your way to heeseung's door and push it open. he’s lying on his bed, the glow of a small battery powered lamp casting long shadows across his face.
"y/n?" he asks, sitting up.
"can i stay here?," you whisper, your voice trembling. "i-i can’t sleep."
his eyes soften and he smirks just a bit. he doesn't hesitate. he moves over, patting the space beside him. "c’mere."
you scramble onto the bed, curling into a ball. he pulls the duvet over both of you and wraps an arm around your waist, pulling you flush against his side. you tuck your head under his chin, listening to the steady, rhythmic beat of his heart. it is the only thing that feels safe in the world.
"i’ve got you," he murmurs. his hand rubs slow circles into your back. "just listen to me. ignore the noise."
you close your eyes, breathing in the scent of him. you feel his chest rise and fall. for a long time, neither of you speak. the rain continues to lash the house, but inside the cocoon of the blankets, it’s warm.
you feel him shift. his chin brushes the top of your head. he pulls you closer, his grip tightening almost imperceptibly. you look up, and he’s already looking down. the light from the lamp catches the gold in his eyes. he doesn't move away. he lets his gaze linger on your lips, his breath hitching.
"y/n," he whispers. it’s a warning and a plea all at once. you want to lean in. you want to erase the few inches of space between you but he closes his eyes and lets out a long sigh, leaning his forehead against yours.
"try to sleep," he breathes. "i’ll carry you to your room once you’re asleep." you feel a cold knot form in your stomach. you didn’t want to go, but you respected the boundaries between you two.
"okay," you agree muttering softly with a nod.
you fall asleep in his arms, but the comfort is gone, replaced by a yearning that feels like a physical ache.
── .✦
a few days later, the sun is back, but the tension has only grown. jake is still away, and he has asked heeseung to keep an eye on you. heeseung is in your room, sitting on the bed while you fuss over him.
"your skin is literally flaking, heeseung. how do you live like this?" you tease, holding a bottle of moisturizer.
"i’m a simple man. soap and water does the trick," he says with a soft smile.
"you’re a disaster," you reply. "sit still."
you lean over him, your face inches from his. he watches you with a quiet intensity, his eyes following every movement of your hands. you gently apply the cream to his cheeks, your fingers massaging the skin in slow, circular motions. you like taking care of him. you like the way he lets you, the way he becomes docile under your touch.
"didn’t know you were so bossy," he
whispers, though he is smiling.
"someone has to be," you retort. "otherwise you would probably forget to eat."
"maybe i like it when you take charge," he says.
you laugh, but the sound dies in your throat when you realize how close you are. the air is thick again. you try to get a better angle to reach his forehead, and you shift, sliding forward until you are sitting partially in his lap.
your heart hammers against your ribs. you freeze, your hands still resting on his face. he doesn't move. he just looks at you, his pupils blown wide.
then, it happens. as you shift again, your crotches graze. it’s a brief, accidental touch, but it feels like an electric shock. you gasp to yourself softly, your eyes widening slightly. beneath the thin fabric of his sweatpants, you feel it. he’s hard. incredibly hard.
the shock lasts for a second before a sudden, primal heat takes over. neither of you pulls away. instead, he presses you closer. an instinctive need to feel more of him overriding your shyness. you begin to rub against him, a slow, tentative dry humping that starts as an accident and turns into a demand.
he lets out a low, guttural groan, his hands flying to your waist to hold you steady.
"y/n," he gasps. "we shouldn't."
"i don't care," you whisper.
he breaks. he lunges forward, his lips crashing against yours. the kiss is hesitant at first, a question asked in the dark. then it turns hungry. he tastes like mint and longing. his tongue slides against yours, sucking and swirling, claiming you in a way he never has before. you moan into his mouth, your fingers tangling in his hair, pulling him closer.
his movements becoming more urgent. he was gentle, but the raw need was evident in the way he gripped you. you arched your back, a soft moan escaping your lips. the feeling of him, hard and pressing against you, was overwhelming.
he pulls back for a second, his breathing heavy. he looks at you, really looks at you.
"you’re not the little girl i used to know anymore, are you?" he breathes.
his hands slide down, gripping your thighs and pulling them wider. he reaches for the hem of your shirt, looking at you, asking for permission. when you gave a soft nod he gently lifted it. he sees your breasts and he lets out a shaky breath. he reaches out, his thumb brushing over your nipple, which is already hard and peaking. you arch your back, a small cry escaping your lips.
"god, y/n. you’re so beautiful," he whispers.
he leans down, his mouth replacing his fingers. he sucks your nipple into his mouth, his tongue swirling around the areola. he teased you, biting softly, then sucking hard, creating a vacuum that sent sparks shooting straight to your core. the sensation is overwhelming. you feel a pulsing heat between your legs, a wetness that makes you squirm. “so soft," he groaned.
you reach down, your hand trembling as you find the bulge in his sweatpants. you grip him through the fabric, and he nearly jumps off the bed.
"fuck," he groans. you slide the fabric down, freeing him. his cock springs out, thick and pulsing, a bead of pre-cum glistening at the tip. you’ve never seen anything like it. you wrapped your fingers around him, feeling the velvet texture of his cock. he was thick and pulsing, leaking a bit of pre cum that made your grip slick. he let out a strangled noise, his eyes closing.
"let me show you," he whispered. he guided your hand, showing you the rhythm he liked.
"like that. wrap your fingers tighter."
you followed his lead, your thumb rubbing over the sensitive head of his cock. he was shaking, his muscles tensing under your touch.
"like this?" you ask softly.
"yeah," he rasps. "just like that. a little faster." he guides your hand, showing you the rhythm he likes. you watch as your hand slides up and down the shaft, the skin sliding over the head. you hear the wet sound of your grip, a rhythmic shlicking that makes your own core throb. he closes his eyes, his head falling back against the headboard, his hips jerking upward into your hand.
"y/n, you’re gonna be the death of me," he moans.
you move your hand away, your eyes searching his. you want more. you want everything. you reach for your own pants, sliding them off along with your underwear. you are completely bare before him now, your legs shaking.
he looks at you, and for the first time, hesitation flickers in his eyes.
"i don't want to take this from you," he whispers. "your first time. i want it to be perfect. i don't want to be the one who ruins it."
"i want it to be you," you say, your voice firm despite the nerves. "i only want you, heeseung."
he lets out a shaky breath and pulls you back down, his movements gentle and slow. he kisses your forehead, your eyelids, your nose.
"i’ll be careful," he promises. "tell me if it hurts. tell me to stop, and i’ll stop immediately."
he moves between your legs, his knees pushing yours wide. he enters you slowly, the tip of his cock stretching your tight opening. you wince, your fingers digging into his shoulders.
"shhh," he whispers, kissing your jaw. "just breathe. look at me."
you look into his eyes, and the fear begins to fade. he pushes in another inch, then another. you feel a sharp sting, a feeling of being too full, but he stops. he stays still, letting your body adjust. he whispers sweet things to you, telling you how much he loves the way you feel, how long he has wanted this.
when he finally pushes all the way in, you let out a long, shuddering breath. he stays there for a moment, his forehead pressed against yours.
"you okay?" he asks.
"y-yes," you whisper. "don't stop."
he begins to move. it is slow at first, a gentle rocking that focuses on the friction. the sting fades, replaced by a building pressure. he starts to pick up the pace, his thrusts becoming deeper and more confident.
the sounds of the room change. the soft whispers are replaced by the sound of skin slapping against skin, the squelching of your natural lubrication mixing with his. your breasts bounce with every movement, his hands gripping your hips to keep you pinned.
"you feel so tight," he groans, his voice vulgar and raw. "fuck, y/n, you’re squeezing me so hard."
you wrap your legs around his waist, pulling him deeper. you feel him hitting your cervix, a deep, blunt pressure that sends sparks through your entire body. you moan, your voice high and needy.
"more," you beg. "please, more." he obliges, his movements becoming frantic. he is no longer the gentle protector. he is a man possessed. he thrusts into you with a sudden, overzealous energy, his cock slipping out almost entirely before slamming back in. the sound is wet and loud, filling the quiet room.
you feel the tension building, a coil tightening in your lower belly. he is close too. his breathing is ragged, his face strained with effort.
"i’m going to-," he gasps. "i’m going to come."
"m-me too," you cry out. "do it with me." he gives one final, powerful thrust, burying himself as deep as he can go. he freezes, his body shuddering as he releases. you feel the hot, thick pulses of his cum filling you, a warm flood that makes you peak right along with him. you scream into his shoulder, your muscles contracting around him in waves of pleasure.
he collapses on top of you, his heart racing against your own. he doesn't pull away. he stays there, holding you, his breath hot against your neck.
neither of you says a word. there is no confession of love, no promise of a future. there is only the heavy silence and the knowledge that everything has changed.
── .✦
the next morning, you wake up to a cold bed. you walk into the kitchen, your body feeling heavy and sore. jake is there, eating cereal and talking to heeseung. they are laughing about some meme niki made of sunoo in their groupchat.
you stop in the doorway. heeseung looks at you. for a split second, the mask slips. you see the longing, the guilt, and the raw desire in his eyes. then, he looks away, turning back to jake with a casual smile.
"morning, kiddo," jake says, oblivious. "you look like you slept for a thousand years."
"i did," you mutter.
for the next week, it’s as if it never happened. heeseung treats you with a polite, distant kindness. he doesn't touch you. he doesn't linger. he follows the rule again: you are off limits.
the silence between you becomes a torture. every time he walks past you, you feel the ghost of his touch. every time he laughs at something jake says, you feel a surge of resentment. you begin to believe that for him, it was just a moment of weakness. a one time touch that cannot ever happen again.
the pressure reaches a breaking point when jake brings up a topic over dinner.
"so, my friend from college, minho, is coming to visit next month," jake says, chewing on a piece of chicken. "he’s a great guy. smart, funny, and he thinks you’re cute from the photos i showed him. i think you two would reaaally hit it off."
you felt heeseung stiffen beside you. you didn't have to look at him to know he was reeling. it was like he'd been punched in the gut.
"i don't really want to date anyone right now, jake," you said softly.
"come on, just one date. he's a catch," jake insisted. "right, heeseung? minho's a catch, isn't he?"
heeseung didn't answer for a long time. when he did, his voice was cold. "i think she said she's not interested, jake. leave her alone."
jake blinked, surprised by the sharpness of his tone. "whoa, okay. just a suggestion."
heeseung suddenly stands up, his chair scraping softly against the floor.
"i’m gonna get some air," he says, his voice tight. he disappears through the sliding glass door.
── .✦
that night, you couldn't sleep. you walked out onto the balcony, curling up in the large hammock, staring at the city lights. the air was cool, the stars blurred by the city's glow. you felt a presence behind you.
you hear the door open. heeseung slides into the hammock beside you, his shoulder brushing yours, the fabric dipping under his weight. he doesn't look at you. he stared out at the skyline for a long time before he spoke.
"i’m sorry," he whispers. his voice is broken, thick with an emotion he can no longer hide.
"for what? you don’t owe me anything.." you say softly despite the internal tug on your heart.
"for the way i have been acting.. pretending that night didn't happen. for being a coward and acting like i don’t want you every single second of the day." he turned to look at you, and his eyes were swimming with emotion.
"i can't stand it, y/n. i can't stand the thought of you with someone else. i can't stand the way i have to act when jake is in the room."
"then.. why do you keep doing this?" you whisper. "why do you keep pushing me away?"
"because he’s my bestfriend," he says, referring to jake. "and i love you. and in my head, those two things cannot exist at the same time. i promised him years ago that i'd never... that you were off limits. if i take you, i'm betraying the one person who's always had my back."
he reaches out, taking your hand. he slowly guides it to his chest, pressing your palm flat against his heart. it’s racing, drumming a frantic rhythm against his ribs.
"do you feel that?" he asks. "that’s you. it’s always been you. since you stopped being the cute little sister and became the only person i can think about. and i’m terrified, y/n. i’m terrified of losing jake, but i am more terrified of a life where i cannot be with you."
“heeseung..” you muttered in utter shock. you feel a tear slide down your cheek.
"i love you too," you whisper.
he didn't hesitate this time. he pulled you into a kiss that tasted like relief and desperation.
"we have to be secret for a while," he murmurs against your lips. "just until i figure out how to tell him."
"i can do that," you say.
the secret is a thrill. stolen kisses in the laundry room, holding hands under the dinner table while jake talks about his day, and late night visits to each other's rooms when the house is silent. the yearning is replaced by a simmering passion, a shared secret that binds you together.
but secrets have a way of leaking. two weeks later, jake walks into the living room while you and heeseung are entangled on the sofa. you’re draped across his lap, your head tucked into his neck, and he is kissing your temple with a tenderness that is impossible to mistake.
── .✦
the end came on a rainy tuesday. jake had come home early from class and walked into the living room to find you and heeseung tangled together on the couch, heeseung's hand slid deep under your shirt and your legs wrapped around his waist.
they both froze. jake's jaw dropped, his eyes darting from you to heeseung.
"what the actual fuck?" jake yelled.
heeseung stood up, stepping in front of you protectively. "jake, let me explain."
"explain? you're fucking my sister! you're my best friend! how long has this been happening?"
"a while," heeseung said, his voice steady despite the tension. "and i'm sorry i know i broke the promise. i know i crossed the line. but i love her. i really love her."
jake looks at the two of you. he looks at the way you are clinging to heeseung, and the way heeseung is looking at you as if you are the only thing in the world that matters.
jake looked like he was about to explode. he paced the room, swearing under his breath. you held your breath, your heart hammering. then, jake stopped and looked at heeseung.
"you really love her?" jake asked, his voice quieter.
"more than anything in this world," heeseung replied.
jake sighed, rubbing his face with his hands.
"god, i'm so stupid. i should've seen it. the way you two look at each other... it's disgusting, honestly." he looked at you and rolled his eyes. "you have terrible taste in men, y/n. he's a nerd."
you laughed, a sob of relief escaping you as you threw your arms around your boyfriend. "i know, but he's my nerd."
he steps forward and points a finger at heeseung. "if you break her heart, i will actually kill you. i will bury you in the backyard and tell everyone you moved to busan."
heeseung laughs, a sound of pure relief. "deal."
jake shakes his head, a small smile on his face. "get a room, you two. seriously. i can't handle the PDA in my own house."
“as if you and yunjin aren’t all over each other!” i yelled at him while giggling.
once jake leaves, heeseung pulls you back down into the cushions. he wraps his arms around you, pulling you into a tight, warm embrace.
"i can’t believe he is okay with it," he whispers.
"i told you he loved us," you giggle.
you pull back and begin peppering his face with tiny, cute kisses. one on his forehead, one on each cheek, one on the tip of his nose.
"stop it," he laughs, though he is leaning into you. "you’re too cute."
"i’m allowed to," you say, kissing his chin. "i’m your girlfriend now."
he stops laughing, his expression turning soft. he cups your face in his hands, his thumbs stroking your cheekbones.
"i love you so much baby."
"aww i love you too, my hee."
you cuddle into him, the weight of the world finally lifted. for the first time in your life, everything is exactly where it is supposed to be.
🪽authors note ~ should i do boxer hee next? 👀