Stallion Serum: Summer’s Challenge

Disclaimer: All characters depicted in this story are aged up to 18 or older, regardless of their ages in the original source material. All encounters portrayed are consensual. This work is a piece of fanfiction, intended for entertainment purposes only, and does not reflect the canon of the original story. In this story all characters are above 18 and are in the lab during a college break. Content is created for an adult audience (18+) and may include mature themes. Reader discretion is advised.

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Summer and Morty lingered in Rick’s lab late that night, college break giving them time to tackle separate projects for extra credit. The hum of alien tech filled the air as they worked, unaware of the chaos about to unfold. But Morty’s mind wasn’t on his project. Jessica’s jab, “big guys only,” had gutted him. Her party this weekend was his chance to prove her wrong. He recalled Rick’s drunken rant last week about a “stallion serum” for an alien breeding farm, “Gonna make those space mares pop!” while pointing at a glowing vial. Desperate, Morty rummaged through shelves, Growth Tonic, Limb Regener-X, until he spotted the glowing Nano-Enhance Serum: Virile Surge. Jackpot.

Hands trembling, he popped the cap and slathered the goo on his dick, its icy sting sparking a blaze. “Aw, jeez!” he muttered, the burn spreading. He stroked, each tug searing. His testicles darkened to glossy black, swelling heavy, while the base of his cock turned jet-black, the upper shaft fading to a lighter, flushed tone, the head bloating wide, oozing thick precum. “Shoot!” he gasped, as it morphed into a horse-like beast, longer than his forearm, thick as a beer can, reeking of sweaty leather tang. It pulsed, heavy, demanding. “Rick!” he shouted, voice cracking, but Rick was off-planet, probably drunk. Summer stood at the workbench, bent over soldering, backside facing him, crop top hugging her curves, white short shorts flashing pink panties through the gap, her thigh gap shifting as her legs swayed, ponytail bouncing, earbuds blasting.

“Summer!” he croaked, lurching forward, the beast swinging, precum splattering the tiles, vial slipping from his hand. She yanked out her earbuds, whirling, eyes wide. “Morty, what the heck?” she yelled, soldering iron clattering. The sweaty tang hit her nose, raw and filthy, cheeks flushing. She snatched the vial, scanning it. “Nano-Enhance Serum: Virile Surge,” she read, squinting, then barked, “Warning: For Stallion Only? You’re such a moron, Morty. What, trying to impress Jessica with a horse dick?” Morty’s face burned. “It was an accident! Help me!”

Summer slammed the vial down, breath catching, cheeks pink in the lab’s thick air. She snatched a holo-tablet, fingers shaky. “Idiot,” she snapped, scrolling fast, screen glow highlighting her flush. The tang stirred heat in her core. She shifted, thighs pressing, shorts tight. “Nanobots in you. Gotta flush every drop. You’re a science experiment.” Her eyes flicked to the pulsing shaft—black base, flushed tip, gleaming head—then away, face reddening. Morty caught her sweet, tangy scent from her damp panties. “Here? With you?” he stammered, cock growling. Her lips parted, chest heaving, heat electric. The lab crackled, lights dimming, consoles sparking.

Guilt stabbed Summer, her core warming. This is so bad, she thought, legs twitching, but her slit dampened. “No way, Morty,” she spat, arms crossed. “Not your creepy lab assistant.” The tang thickened, panties clinging. Morty pleaded, “It’s killing me!” Precum splatted tiles. “Boo-hoo,” she mocked. “Boner death? Classic Morty.”

Her clit ached, pulling her closer. She loved chaos—stealing Rick’s portal gun, dodging aliens—but this was raw, forbidden. His shaft’s heat drew her. So bad, she thought, his desperation eroding her resolve. “You’re such a loser,” she hissed, bending low, ponytail swaying. “Just fixing your mess.” Her fingers brushed the scorching shaft, too thick to grip, flared head glistening. She stroked slowly, wet shlicks echoing, Morty groaning, hips jerking. “Oh, jeez, Summer!” he gasped. “You’re botching this,” she quipped, strokes quickening, her scent mingling with his musk, thighs quivering. Her slit burned, panties soaked. Why’s it not working? she wondered, eyeing the oozing tip. I shouldn’t, she thought, but her tongue grazed the salty head. A jolt hit, slit tightening, and she sucked shallowly, moaning, restraint crumbling.

Summer’s sucking grew frantic, lips stretched, tongue lapping. She pulled back, precum stringing, whimpering as she bent over. Morty’s hands slid down her back, tracing sensual arcs, her moans vibrating his shaft. His fingers slipped under her shorts, past her panties, grazing her slick folds, circling her clit. A muffled scream escaped, wetness surging, juices streaming. Pleasure warred with panic; she pulled back, gasping, gripping his shaft. “Morty, no!” she snapped, shoving him. Too far, she thought, heart racing. “I didn’t mean to!” he stammered, hands freezing.

Morty’s fingers traced her outer lips, parting her folds with a wet glide. A shock jolted Summer, hips twitching. “We can’t,” she whimpered, slit blazing. His fingers grazed her clit, sparking tremors. Shame burned, resolve fading. Why’s it so good? she thought, core gripping his finger as it dipped deeper, coating his hand. Moans swelled, lab fading. Morty pulled back, eyes wild, stammering, “Summer.” He stepped closer, cock bobbing, precum gleaming. Her heart pounded, craving more. I shouldn’t, but shoot, she thought, need winning. She tugged off her shorts and panties, climbing onto the counter, legs wide, slit glistening. “Maybe sliding your shaft on my slit will help you get off, dork,” she rasped, eyes locked. Morty nodded, shaky, his cock brushing her slit, sliding slow, grazing her clit, sending jolts. Juices pooled, folds trembling. He paused at her entrance, pressing the flared head, her tightness yielding. She nodded faintly, moans betraying her. Pleasure surged, slit quivering, juices streaming. Each push sent a searing wave, resolve crumbling. I can’t… but it’s too good, she thought, aching. Her breath caught as he pressed deeper, the head stretching her. “Just the tip, Morty, no more,” she rasped, half-resisting, half-yearning.

Morty’s slides grew deliberate, slick drags echoing, stoking Summer’s hunger, hips bucking. He paused, pressing the flared head deeper, widening her entrance, lips gripping. Each pause teased her limits, shame warring with hunger. “Dang,” she gasped, nails clawing the counter, moans raw. This is wrong, but I crave it, she thought, pleasure overwhelming guilt. Her resolve crumbled, juices soaking the counter, body screaming. As Morty paused, the head poised, stretching her lips, his fierce gaze met hers, her ache consuming her. Need drove her, urging him on.

Morty froze, tip searing, breath ragged, hands shaky on her hips. His gaze asked, Can I? Summer’s heart pounded. I shouldn’t, she thought, shame flaring. But her slit burned, musk clouding her senses. Her body begged yes, the taboo thrilling. I want it—damn the consequences, she thought, choosing the rush. “Do it,” she rasped, fierce, legs wrapping his waist, guiding him. I need it, she thought, restraint shattered.

Summer’s grip tightened, nails gouging the counter as Morty pushed, the flared head stretching her tight slit. “Oh!” she groaned, thighs clenching. It’s too big, but I need it, she thought, hunger knotting. He pushed harder, her lips yielding to pulsing fullness. Juices spilled, pooling beneath. “Don’t mess this up,” she hissed. On the third try, the head surged through, bliss filling her. The shaft drove deep, nudging her cervix, a faint bulge rippling her stomach. It’s breaking me, she thought, gripping tight. But I want it.

Morty groaned, thrusts slow, each drag pulling her walls, wet glides echoing. The flared head brushed her cervix, sparking jolts. Summer’s fingers rubbed her clit, frantic, gasping, “Harder, wimp!” Her legs pulled him deeper, body shuddering, cervical jolts reverberating. Pleasure rushed, her core a trembling vise. It’s too much, she thought, fingers grazing the bulge. Morty’s thrusts quickened, each spark driving her wild. Her screams filled the lab, console rattling, a wire flickering. “Not totally useless!” she moaned, slit dripping, nearing the edge.

A burning pulse stormed through Summer, each grind jolting her cervix, waves ripping through. Her gasps synced with the console’s hum, clit a searing knot. This is messed up, she thought, shame clawing, yet her core gripped tighter, chasing euphoria. “Keep going, loser!” she panted, fingers frenzied. Morty’s hands bruised her hips, thrusts deep, cock swelling. “I’m so close,” he rasped, trembling. She’s perfect, he thought, fighting to hold back. “Get me there and pull out!” Summer panted, core tightening. Their eyes locked, defiance softening, a spark igniting. This rush beats any portal jump, she thought, alive with it.

Summer’s moans softened, pulse racing as Morty’s thrusts quickened, driving her to the edge. Her thighs trembled, core tightening, pleasure coiling, breaths sharp. The lab blurred, just them, lost in the forbidden rush. As her arousal peaked, Rick’s yell echoed down the hall: “Morty, Summer, anyone around?” Panic spiked, her heart lurching, fear igniting her climax. Morty’s thrusts turned feral, pulsing her slit. She bit her lip, stifling a scream, but her body convulsed. Their climax hit like a misfired portal gun, chaotic, unstoppable, fear and lust colliding. “Oh shoot, Rick!” she gasped, orgasm surging, juices gushing, tiles soaked. Her spine arched, pleasure tearing through, slit clamping Morty’s cock. I’m shattering, she thought, shudders relentless. “Oh shit!” Morty gasped, trapped by her grip, balls churning, nanobots flushing out. His cock pulsed, glowing jets flooding her cervix, filling her womb with a hot, viscous rush, sparkles swirling, warming her core. She’s killing me, he thought, balls lightening. Summer’s eyes widened—He didn’t pull out! “You absolute idiot!” she snarled, shoving him, a second wave shuddering through, juices splashing the counter.

Her scream ripped free, raw and quaking, her slit gripping Morty’s cock in a relentless vise. Morty’s shout followed, cum surging in an uncontrolled flood, stray strings of cum spilling from her pussy, thick and viscous, a horse load unleashed. Their convulsions lingered as Rick’s boots echoed faintly, his grumbling still a hallway off. “Morty, you unloaded a freaking stallion’s worth in me!” Summer hissed, half-shocked, half-snarking, her glare cutting through her shudders. “Jeez, Summer, it’s not like I planned a flood!” Morty stammered, cheeks blazing, hands flapping uselessly. A faint mutter—Rick’s “Stupid kids better not touch my stuff”—tightened their nerves, juices pooling on the counter. Panic surged, Summer snatching her shorts, dripping and furious, while Morty fumbled his jeans, legs shaky as a rookie adventurer. They dove for the closet, the door slamming shut, a slick trail gleaming behind, a wire caught in the frame, betraying their frantic escape.

Sweaty skin pressed in the tight closet, Morty’s cum trickling from her core, her thighs slick. His flaccid cock, now human, brushed her slick slit, a glob of cum squirting free. A quiet moan escaped Summer, instantly hushed, as it dribbled down her thigh. “Stay quiet, stay quiet,” she muttered under her breath, a mantra against panic. “You’re a walking disaster, Morty,” she whispered, half-snarking, glaring at his shrinking shaft. “Don’t screw this up, don’t screw this up,” Morty whispered back, trembling, guilt and desire clashing. As her moan faded, Rick’s boots scuffed outside, a faint mutter cutting through: “What’s this mess? Damn kids threw a party.” He sniffed, grimacing. “They’re cleaning this crap tomorrow, or they’re toast.” Panic flared, Summer’s pulse racing as the trail’s gleam shone through the door crack. That trail’s our doom, she thought. “Quiet,” she hissed, gripping his arm. “You owe me, dork.” Morty’s breath hitched, thinking, Oh crap, Rick’s gonna kill me. Her core pulsed, shame and thrill warring. Would I do it again? she wondered, stunned by her Yes. “This stays between us,” she whispered fiercely, their heat a silent vow.