~~Forbidden Brotherly Desire~~ (Pt 5)
What happens when a Cuntboy find out that you have got a girlfriend when he is there and too desperate for... YOU?
Top!male reader, yandere cuntboy, own character, murdering, extreme jealously, masturbation, desperately seduction, too obsessed with reader, submissive yandere, murdering, breasts on male character. smut?
Part 1 / Part 2 / Part 3 / Part 4 / Part 6 / Part 7 / Part 8
Shadows of Obsession
The week alone with Y/N had been a tease, a taste of what Yuta craved. Yuta's touches lingering longer each day, his pleas for help with his body's demands growing bolder, but reality crashed back when parents returned, glowing from their trip, and life shifted. Life resumed its rhythm, school pulling Y/N into his social whirl. Yuta watched from the shadows, his body a constant betrayal—breasts swelling fuller each day, milk leaking at the slightest arousal, cunt perpetually slick with thoughts of his stepbrother. He practiced poses in the mirror, arching to thrust out his heavy tits, spreading his legs to admire the plump lips of his pussy, but self-loathing lingered beneath the desperation.
Y/N changed first. After that breast-kneading incident, Y/N threw himself into school, his phone buzzing more often, laughter spilling from calls that made Yuta's stomach twist. Y/N noticed the change in his little stepbrother—the way Yuta's body pressed too close, the moans that echoed too sweetly during 'massages.' This can't go further, Y/N thought, pulling back. he'd grown distant, eyes skimming over Yuta like he was just furniture. 'We can't do that stuff anymore,' he'd muttered one evening, avoiding Yuta's pleading gaze. 'It's not right.' Yuta's heart twisted, but he nodded, hiding the fire in his belly.
Y/N started dodging Yuta's hugs, locking his door at night. Yuta felt the rejection like a slap, his heavy breasts aching not just from milk but from the void Y/N left. Upset gnawed at him, but desperation fueled bolder moves. Unbeknownst to him, Y/N had met someone at school—a girl named Mia (just random name for this temporary character), with sharp wit and easy laughs that drew crowds. Y/N dove in, using the relationship as a shield against the confusing pull Yuta exerted.
Yuta sensed the shift immediately. Y/N's phone buzzed constantly, his smiles brighter when he thought no one watched. Parents proud secretly as they could sense their son had found someone he love though Upset gnawed at Yuta, but he doubled down on seduction. Mornings, he'd slip into Y/N's oversized shirt, the fabric draping loose over his curves, hem barely skimming his thighs. No underwear—just the shirt swallowing his frame and clinging to his damp skin, nipples poking through like invitations, his plump cunt lips peeking if he bent even slightly, ass cheeks jiggling free. 'Thanks for the shirt, Oni-chan,' Yuta would purr, twirling so the hem lifted, exposing the round swell of his cheeks. Y/N's jaw clenched, eyes darting away. 'Stop wearing my shirt only. And put some pants on, Yuta. You're not a kid anymore.' But Yuta saw the flicker—the way Y/N's pants tented briefly before he turned.
Other days, Yuta squeezed into too-small outfits: a crop top straining and stretching taut over his massive breasts, the fabric translucent with sweat and milk stains; tiny shorts riding up his ass crack, shorts wedged tight between them, the thin denim outlining his juicy pussy. He'd lounge on the couch, legs spread casually, hoping Y/N would stare, touch, fuck him senseless. Yuta begged Y/N to watch a movie together. 'Sit with me, Oni-chan? I'm lonely.' Y/N sat at the far end, phone in hand and eyes still on it, trying to ignore the way Yuta's hand 'slipped' to rub his inner thigh. Then as he had a glance over to 'check', Y/N's eyes would flick away immediately, cheeks heating. 'Yuta, put on real clothes. This isn't funny.' But Yuta pouted, clinging to his arm, grinding his hip against Y/N's thigh until he shrugged him off and fled to his room.
One afternoon, Yuta couldn't resist and burst into Y/N's room uninvited, desperate for attention. Y/N sprawled on his bed, phone in hand, thumbs flying. Yuta pounced, climbing onto the mattress and draping himself over and wrapping arms around Y/N's fit waist, face nuzzling his chest, breasts squishing against it. 'What're you doing, Oni-chan? Play with me instead. You've been ignoring me.' Y/N stiffened, trying to pry him off, but Yuta clung tighter. Then A notification pinged and Yuta peeked —Mia’s name with heart beside flashed on the screen before Y/N tilted it away. Yuta's eyes caught it, heart plummeting. Girlfriend? No, it couldn't be. He froze, then forced a laugh. 'Who's that? Friend?' Y/N pocketed the phone, pushing Yuta gently. 'None of your business, squirt. Go do homework.' He pulled back, feigning a yawn as he continued peeking — Y/N texts to 'Mia,' hearts and flirty emojis. Jealousy hit like a punch, Yuta's vision blurring. No... He is mine. And the seed planted.
Patterns emerged: Y/N glued to his phone, sneaking out evenings, returning late with rumpled clothes and a secretive grin and smelling of perfume. Yuta's stomach churned, jealousy festering, hot and ugly, twisting his fantasies. He'd masturbate furiously in his room, fingers plunging into his sopping pussy while imagining Y/N's cock slamming into him instead of some girl. Mine, Oni-chan. Only mine.
One night, as Y/N laced shoes for another 'hangout,' Yuta blocked the door, arms crossed under his tits to lift them provocatively. 'You're always gone. What's going on? Who are you hanging out with? Tell me.' His voice trembled, holding back the urge to scream, to claw. Y/N sighed, rubbing his neck. 'It's nothing. Just friends.' Yuta stepped closer, body pressing in, hand on Y/N's chest. 'Liar. I see you smiling at that screen. Who is she?' Clingy, insistent, Yuta wouldn't budge. Y/N cracked. 'Fine. Her name's Mia. We're… seeing each other. Happy? So you need to back off, Yuta. This clingy stuff—it's too much. We're brothers. Boundaries, okay? From now on.' The words sliced deep, Yuta's world cracked, tears pricking his eyes, but he nodded, whispering, 'Sorry, Oni-chan.' Inside, fury roared.
Officially dating now, Y/N balanced it all: dates with Mia, brotherly check-ins with Yuta. He cared—brought home snacks, asked about school with brotherly pats on the head—but no more touches. He fought the pull of Yuta's seductions, the way those heavy breasts strained against clothes, the jiggle of his ass when he bent over. When Yuta sat on his lap during movie night, everything is normal until Yuta ground subtly, trying to sandwich Y/N's crotch between his fat ass cheeks. Y/N lifted him off gently. 'Not like that.' Yuta's pussy ached from the denial, but he plotted.
Dates became Yuta's battlefield. Whenever Y/N dressed for a date—collar popped, hair styled—Yuta pouted and clung onto Y/N. 'Don't go! Stay with me!' voice would lace with fake panic and he'd grab Y/N's sleeve, breasts pressing into his arm, cunt throbbing with need. Y/N pried free. 'I'll be back late. Be good.' 'Oni-chan, wait!' he'd cry as Y/N headed out. Soon as Yuta became desperate, he escalated as he sent texts: "Oni-chan, the stove's on fire! Help!" Y/N bolted back home mid-date, Mia was left confused at their peaceful date. bursting through the door worried. 'What happened?' he'd demand, scanning Yuta's unharmed body, only to find Yuta 'safely' in the kitchen, no flames. Yuta would pout, 'Sorry, false alarm. Just scared.' Y/N would groaned and scolded, face thunderous. voice sharp: 'That's twice this week. Stop lying to sabotage my plans.' Yuta feigned innocence, eyes wide. 'I was scared... sorry.' But Y/N's gaze burned and worry turned to frustration. 'Stop lying, Yuta. This isn't funny. You're making me look bad.' However, Y/N is a good-hearted older brother so how long could he be mad at his cute little brother. After all, he'd stay, comforting the 'upset' boy, Mia texting complaints he ignored.
Days blurred, Yuta's jealousy boiling over. He tried everything: anonymous notes to Mia warning her off, slashing her bike tires, even 'accidentally' spilling milk on her locker to mark territory. Nothing stuck—Y/N adored her. and when Yuta lied that Mia had another boyfriend and she has been cheating on Y/N, Y/N defended her fiercely. 'That's totally a lie, Yuta. She's great. Stop hating your future sister-in-law and give her a chance.' Yuta's limit shattered.
the next day, Yuta's jealousy peaking. He saw them kiss in the driveway once, Y/N's hand on Mia's waist, and rage blinded him. She touches what's mine. He tried everything—anonymous notes in her locker warning her off, slashing her tires—but she brushed it off, and Y/N doted more, loving her laugh, her normalcy. The limit snapped.
One evening. Parents out, Y/N at store to buy gift for his girlfriend. Yuta alone with Mia when she came by to wait. 'He's running late,' Yuta said sweetly, inviting her in. As they sat, his mask slipped. 'Stay away from Oni-chan. He's mine.'
Mia laughed, flipping her hair and crossing her arms. ''What? You're his brother, Dream on and back off, freak. Y/N's with me." Rage exploded. As Mia was standing up and about to walk away, Yuta lunged, hands around her throat as she crumpled on the couch, Mia tried to screamed but couldn't since Yuta's grips was too tight, eyes become darken as she couldn't breath anymore... Yuta continued squeezing until her struggles weakened, eyes glazing. As Yuta notice that Mia is not moving anymore and is lifeless, he immediately let go and panic surged, but... so did triumph. As soon as he clamed down, He dragged her limp body to the backyard, ignoring the way the dead's eyes is gazing too intensely straight at him, digging frantically in the soft earth under the shed, burying her deep, covering with dirt and leaves. Hands shaking, he cleaned up the mess and washed the blood, heart pounding. Now he's free. For me.
That evening, Y/N returned hours later, phone clutched tight as it was blowing up with unanswered calls to Mia, calls going to voicemail. 'Mia's not answering. We had plans, and… nothing.' he paced the living room, worry etched his face. Yuta curled on the couch, feigning concern, legs tucked to hide the fresh slick between his thighs from the thrill. 'Maybe she's busy, Oni-chan. Don't worry.' Y/N slumped beside him, head in hands. 'I hope she's okay.' Yuta scooted close, hand on his thigh, voice soft. "I'll keep you company. Whatever you need." His cunt throbbed, imagining Y/N's cock slamming in, claiming what was always his. Soon.... very soon... just wait, my Oni-Chan~
'She vanished after our place,'
Y/N began to feel frustrated as Mia still hadn't contact him after days. Y/N had contacted her family too but no one knows where she want and one of her family had already contacted to police. Yuta curled on the couch, acting oblivious. 'Maybe she went somewhere else? Don't worry, Oni-chan. I'm here.' He patted the spot beside him, breasts heaving innocently. Y/N sat, head in hands. "FUCK! THOSE FUCKING POLICE SAY NO TRACE! HOW AM I SUPPOSED TO BE CLAM WHEN I STILL CAN'T CONTACT HER!" Y/N groaned and Yuta scooted close, hand on Y/N's knee, cunt wetting at the vulnerability. 'I'll make you feel better. Let me help, like before.' Y/N shrugged him off gently. 'Not now, Yuta.' But Yuta planned in secret—more seductions, more excuses to touch, more excuses, until Y/N broke and filled his needy holes. With Mia gone, Y/N would crack, see only him.
That night, alone in bed, Yuta fingered his dripping pussy, imagining Y/N's cock finally claiming his holes, breeding the body he'd once hated but now wielded as a weapon. Soon, Oni-chan. You'll fuck me raw, forget her forever. He came with a shudder, milk spraying his sheets, resolve hardening. The game had escalated, and Yuta would win—no matter the bloody mess on his hands. With Mia gone, Y/N would crack, see only him.
Part 1 / Part 2 / Part 3 / Part 4 / Part 6 / Part 7 / Part 8
