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“Are you ready?”
Standing on the other side of the circle, her face lit by the flame of seven candles, Cecilia rolled her eyes at his brother. “Just do it.” She snapped.
Lucius frowned but obediently lit a match, eyes fixated on the eighth candle right in front of him.
This- This was it.
The moment he lit the eighth candle, they would be able to summon a demon. An actual demon!
Despite his reservations, excitement licked down Lucius’s spine. He gulped, heart pounding in his chest.
For the longest time, he had been fascinated with stories about the supernatural. Morbid tales of demon contracts, of Mephistopheles and Faust, have occupied his imagination since he was young. But he never had the guts to actually delve into the specifics - the spells for summoning a demon.
Lucius’s eyes darted towards Cecilia.
Surprisingly, it was his sister that made that last leap. Cecilia, who had come home a fortnight ago and pulled Lucius aside after dinner to talk to him. Normally, they were like night and day - Lucius, a gangly nerd occupied with his books and Cecilia, the classic blond popular girl with dozens of men wrapped around her little finger.
Growing up, it hadn’t always been that way - he remembered, with a pang, a time when he used to shadow her, trotting behind her and her friends. Being her little dress-up doll, enduring skirts and dresses when their parents were away, and giggling as she dusted his cheeks with blush, soft bristles tickling him.That all stopped when she entered her teens. When following her after dinner, Cecilia snapped at him - eyes furious, nostrils flaring - yelling for him to ‘stop bothering her!’ He obeyed, and really, on second thought, maybe he should have requested something in exchange for helping her to get social clout. It would have been the rational choice after suffering the hurt of being shut out like that.
But when she showed him the book she had bought from some old bookstore, full of arcane spells- he knew he couldn’t pass up the opportunity to summon a real demon.
Tonight was just perfect. A time when their parents were both out on a business trip; a Friday night when most of their neighbours were off drinking and partying. They had virtually the entire neighbourhood to themselves. No one would notice if anything went wrong.
Hands trembling, Lucius held the lit match atop the eighth candle and counted to three. On ‘three’, he quickly extinguished the match - blowing it out and discarding it in a cigarette holder, to be thrown away later. He grabbed the occult book, flipping through its pages to find the one he wanted.
“You know which spell to use?”
“Memorised it,” Lucius replied, tapping the side of his head.
Cecilia smirked. “Good boy.” She purred.
Lucius, trying hard not to blush at the praise, ignored her. He lit the eighth candle and, taking a deep breath, began to recite the words in front of him.
“Ezra ven luminos, ect noct sui…”
The words flowed out of him like silk. Candles flickered and their windows rattled from an invisible wind. There was a tension in the air, like a string being pulled taut - even Cecilia, who always seemed larger than life to him, seemed to be cognizant of it and remained silent.
As Lucius neared the end of the page, the back of his neck prickled.
At their feet, he saw something out of the corner of his eye - a mist, rising from the circle.
It rose steadily, slowly - covering their feet.
“Woah,” Lucius heard his sister whisper. He ignored her, focusing on the words in his mind, his hands wet and clammy as growing whispers joined his chant:
“Ect noct lumos, ect noct sui…”
The mist morphed - vapour rising from between the floorboards, joining the mist and thickening it into a fog. A fog that covered their lower halves and gradually filled the room. A fog that acted as a wall between Lucius and his sister. He could no longer see her - nor hear her. Even the words on the book, inches away from his face, became difficult to parse. The room was silent except for the sound of his chanting. Something like a hand brushed over his chest. He shivered, tongue stumbling over the next words, “E-Ect noct sanguis, von lumos, grieve…”
“Eva…” A voice - distinct, yet soft - murmured. Lucius jolted.
Who was that? He gulped. Sweat dotted his brow. “Eva-”
“Graefzlins…”
“G-graefzlins.” Something sharp pressed against his back. Lucius wanted to scream.
“Ect noct incubo.”
“Ect noct incubo!” As the words slipped past Lucius’s lips in a panicked rush, his brow furrowed. No. No, that wasn’t quite right. It was ect noct somnus wasn’t it-?
“Ah-!”
Lucius jumped to his feet, book dropping to the floor, forgotten. His eyes were wide, his heart pounding at the shout. That voice… “C-Cecilia?” His voice shook. He squinted into the fog but he couldn’t see a hint of his sister. Panic clawed up his throat. “Cecilia!”
For a while, he heard nothing. A soft giggle emerged. Lucius shivered, his skin crawling at the sound.
“Hello, little brother~” Her sister’s voice cooed.
Alarm bells rang in the back of Lucius’s head. That was not his sister. Inhaling sharply, he quickly took a step back.
At his retreat, the air sizzled - the smell of ozone suddenly descending upon the room. Lucius froze, then carefully took another step back, then another, and not too soon as a spark appeared in the fog. His eyes widened.
With a shout, Lucius ducked to the floor, arms covering his head.
A loud BOOM rattled the house as the spell circle exploded.
Lucius squeezed his eyes shut, trembling as bits of plaster and burnt wood rained down onto him. The smell of smoke quickly filled the room. Lucius coughed, half-expecting the fire alarms to start going off. When they didn’t, he turned around, peering at where his sister was. Smoke and remnants of the spell’s fog still covered the entire room. Lucius tensed. “Cecilia…?” His voice trembled.
A sudden gust of wind caught Lucius off guard. He squeezed his eyes shut, arms raised reflexively. After a few moments, he opened his eyes. The smoke and fog had been dispersed. And without the fog, he could see the damage wasn’t as bad as he expected. The spell circle remained in the centre of Cecilia’s bedroom.
Yet it was who stood across him, in the place where Cecilia used to be, that had Lucius’s jaw dropping.
“Well,” ‘Cecilia’ breathed. Her eyes glittered - red as rubies. “How interesting~”
Lucius reeled.
It was… Cecilia? But it also wasn’t.
Like a strange, alternate version of his sister.
The woman smirking at him had the same face. The same long, blond curls. The same pouty lips.
But having grown at least a foot in height, Cecilia who was five foot ten had become an Amazon close to seven feet tall. Where there used to be slim, athletic muscles, more definition had been added - with visible abs, strong arms lined with muscle, and full thighs flexing. Previously pert breasts had nearly doubled in size - B-cups becoming D’s with pierced nipples, their size exaggerated in the underbust leather corset she now wore. Likewise, slender hips had filled and complemented her larger chest - framed by leather garter belts tied to thigh high leather boots.
But what truly caught his attention was the utterly massive, virile bitchbreaker between Cecilia’s legs.
He- he knew he shouldn’t stare. That changed or not, this was on someone (something) sharing his sister’s face. But Lucius couldn’t take his eyes away from it.
Nearly the size of his forearm, covered in thick, throbbing veins, it looked utterly obscene. A ruddy red base merged seamlessly with Cecilia’s fairer skin over her crotch, forming a sort of sheath. That sheathe extended halfway down the new organ, darkening with every inch. A pitch-black member emerged from the sheath, standing proudly like a spear held aloft. Instead of a fat, mushroomed head like Lucius expected, the cock tapered off and flattened at the tip, forming an equine silhouette. Beneath that cock dangled a hefty package - a pair of plum-sized testes filled with girlspunk. Instead of the clean shave Lucius expected from most girls, coarse, black pubic hair surrounded the base of Cecilia’s cock, with stray hairs all over her balls.
Every part of Cecilia’s new outfit seemed designed to draw attention to the changes between her legs- from the garter belts on either side, to the lack of underwear, to the translucent long skirt that was parted in the middle, solely to expose her hairy penis, to the musk radiating from her groin like a corruptive miasma.
The sight was so unbelievable, Lucius nearly missed the horns atop her head, the slim whiplike tail swaying behind her, and the fact she was staring hungrily at him, a hand curled around her cock.
Lucius flinched and Cecilia laughed, the sound twinkling like bells. “W-who,” his voice shook, trembling at her amusement, “Who are you…?”
“Oh? Don’t you recognise me?” Cecilia smirked. She stroked herself - from root to tip. “It’s me, your big sister~”
What? “N-no you’re not! You’re some sort of, some sort of-”
“Demon?” Cecilia’s smirk widened. “Mm, yeah… funny how that works when just a single word is changed.”
A single word. Incubo.
The spell.
Lucius’s eyes darted to the occult book he had left abandoned on the floor, just a few feet away from him. He inhaled sharply. If a spell from that book could summon a demon or change his sister into one, then surely there’s also a spell to reverse the process, right-?
Making a decision, he shifted and lunged.
“Oops!”
Lucius cried out, managing to throw himself back just as the book went up in flames. He watched in horror as fire swiftly consumed the book - pages turning black and curling inwards, the words becoming little more than ash on soot.
In just a few seconds, the fire extinguished itself- leaving behind a pile of ash and dashing Lucius’s hopes.
“You…” Trembling, mind spinning, and numb with shock, Lucius turned his head. He stared up at his sister. His sister, who set the occult book on fire, ruining every possibility of saving her. His infuriating, annoying, distant big sister who preened, proud of what she had just done.
Anger sparked in Lucius’s chest and grew into a raging inferno. “Why… why would you do that?!” He yelled.
“‘Why’?” An airy sigh slipped past Cecilia’s lips. “You ask such stupid questions, little brother. Isn’t it obvious?”
Lucius froze as she leered at him, half-lidded eyes sweeping up and down his form. A serpentine tongue slipped out of her mouth and Cecilia licked her lips. A clawed hand curled around her horsecock. White beaded at the tip, shimmering like dew.
No. No!
Lucius darted away - or, tried to.
A strong, cordlike tail curled tightly around his waist. Lucius panicked, feet scrambling, but it was too late.
Pulled against a soft, strong chest, feeling arms clamp down around him strong as iron bars, Lucius’s voice gentled. “Cecilia, this- this isn’t you!” he insisted. “It’s the demon. You don’t actually want to- please, please snap out of it!”
“On the contrary, Lucius~” Lucius shuddered as a breath brushed over his ear. “I’ve never felt more like myself.”
In the next moment, sharp claws ripped through Lucius’s shirt and Lucius struggled. “Stop, stop- ah, ahhh~!”
His scream tapered off into a low moan as soft fingers brushed against his nipples. “Harh, ah, ah~ w-what…” He blinked, unable to believe what was happening to him. This must be a dream. No- a nightmare.
A dark chuckle, however, brought him back to reality. “My, my,” Lucius yelped as Cecilia squeezed the puffy red nipples atop his chest. “So sensitive.” she cooed.
“Ah. harh…” Lucius’s face burned with embarrassment and shame. “Nrgh! S-stop it- ah!”
To his horror, Cecilia refused to stop. Her hands trailed over his torso, lingering on his waist, but she seemed preoccupied with his chest. Lucius didn’t even understand why. Sharp claws scraped and flicked at his nipples, bullying the cherry red nubs, and soft fingerpads squeezed them relentlessly.
Against his will, arousal burnt through Lucius’s veins. “Ah~!” he moaned, back arching. He could hear Cecilia giggling next to his ear, could feel her massive horsecock pressing up against the curve of his arse.
“What a girl,” she said mockingly. “Feeling good, from just having your nipples rubbed?”
Lucius whimpered. “Hrngh…” He shook his head in denial.
“No?” Cecilia clicked her tongue. “Lying isn’t cute brother. Guess I’ll have to punish you~”
“W-what-?”
RIIIIP!
Lucius’s jaw dropped. He stared in shock at the scraps of denim on the floor - shredded in one single move by Cecilia.
The world spun around him and Lucius grimaced as he fell - only to unexpectedly land on something soft. He reached out for something - anything! - to wield as a weapon, only to clutch… bedsheets?
Cecilia’s bed. Oh. Oh-
Strong hands pulled his knees apart. Lucius tried to scramble back but once again, Cecilia’s tail grabbed his hands, wrenching them above his head. He inhaled sharply as Cecilia straddled his chest, heavy testes settling on his clavicles. This close, the overwhelming scent of musk had Lucius tearing up.
“Open wide, little brother~” Cecilia sang.
Lucius made a panicked noise. Yet, before he could move, even attempt at escaping, Cecilia shoved her cock forward.
He choked, suddenly finding a huge horsecock stretching his lips, his cheeks to the point of burning.
Hands gripped his hair, stopping him from moving away. She pushed further into his mouth. Lucius nearly gagged. Tears pooled in his eyes as he struggled to take his sister’s gigantic cock. There was so much of it, it felt like he had an entire baseball bat shoved down his throat. And the smell! A musk so concentrated, it would instantly impregnate any girl.
Stop! He wanted to cry out.
His throat vibrated around Cecilia’s length. Cecilia merely groaned. “F-fuck… what a slutty throatpussy you have.” With a lascivious grin, she drew her hips back and slammed them forward.
Another three inches of horsecock were punched down Lucius’s throat. Lucius nearly blacked out as the sheer girth continued obstructing his airway. As Cecilia moved back, he inhaled, only to nearly faint as the enormous length occupied the entirety of his throat, and more.
“Such a perfect cocksleeve,” Cecilia chuckled. She snapped her hips forward. “My own personal fleshlight, made just for me~”
Lucius shuddered.
Thrust. “My cum toilet.”
Lucius gurgled.
Thrust. “My little brother.”
Thrust. Thrust. Thrust, THRUST.
Lucius tried to shove Cecilia away, to even bite down and stop her, but it was no use. The cock plundering his throat and treating him like its own personal fleshlight was too powerful.
He let himself be used, helpless, as Cecilia’s grunts and growls grew louder and louder. Until-
“Coming, coming, coming-!”
Lucius found his face buried against thick, coarse pubes, when he felt the cock in his throat pulse. He panicked, tried to pull back, and in the next moment-
SPUUURT~!
Cum - hot, virile cum - shot out of Cecilia like a jet. It quickly filled the little space left inside Lucius, flowing into his stomach, his mouth cavity.
“Glurgh, glurg, glurg-” He tried to swallow what he could. But there was simply too much of it. Ropes and ropes of semen continued to flow into Lucius’s stomach. Lucius choked on the thick, musky, delicious fluid flowing down his throat as cum overflowed from the sides of his mouth. Globs of semen dripped onto the bedsheets. His belly swelled with the sheer volume of cum filling it - making him look like he was several months pregnant.
At last, when he was beginning to think it would never end, the tsunami of cum finally stopped.
Lucius pulled away with a gasp the moment Cecilia let him go, coughing. Surely. Surely, this was enough-?!
“Oh? What’s this?” Lucius stiffened as sharp nails drifted over his cock. His hard cock.
Cecilia’s grin grew sharkish as she realised what had happened, the same time as him. “Looks like someone enjoyed being facefucked by his own sister.”
What?! His head snapped up. “N-no!” Lucius protested weakly. “That’s not true! I’m not like that! This was, that’s because-!”
Because… because…
“What did I say?” He froze, feeling something press up against his lower half. Cecilia smirked down at him, her finger circling his hole, soaked with her cum. “Lying isn’t cute, Lucius.”
Ah… He whimpered. “I’m soRRYYYYYYYYY ♡!”
His voice rose into an ear-piercing shriek as Cecilia shoved her finger into his hole.
The sudden intrusion had Lucius shuddering. His oversensitive body was expecting some pain but- It felt strange. It felt… good?
“Surprised, little brother?” Blinking, Lucius turned to his sister. Cecilia smirked down at him. “Betcha this little fact didn’t come up in your research…”
What? Lucius stared uncomprehendingly as Cecilia lowered her head. “Demon cum,” she murmured, “has many, many uses once ingested by a human. Including as an aphrodisiac~” Her eyes flashed. “And in turning humans into the perfect bitch.”
…Ah.
In the next moment, before he could even open his mouth to ask how she knew, Cecilia was moving.
Her finger pistoned in and out of Lucius’s hole at a rapid speed - reaching further, deeper, with every thrust.
Lucius’s mind reeled. He could feel every knuckle, every callus, on Cecilia’s finger. His insides felt hot as they clung to his sister, walls rippling and hugging her, as if desperate to keep her inside him. His mouth opened in a silent scream, and Cecilia immediately pressed her advantage.
Without pause, Cecilia slammed her lips against his. A sly tongue slipped effortlessly into his mouth. At the same time, another finger was added to the one fucking Lucius. Lucius moaned, the sound swallowed by Cecilia’s mouth.
Like the fire that consumed the book, it felt as if tongues of flame were licking him - devouring him from the inside. Burning him alive. His head felt heavier and heavier, as if drowning in smoke. Rationality bled away. A haze fell over his mind. His eyes glazed over.
Then, Cecilia curled her fingers.
Lucius’s body betrayed him for the second time.
Pleasure bloomed. Electricity sparked down his spine. Thin fluid spurted onto his belly and Lucius thrashed as waves upon waves of ecstasy crashed into him, melting his brain - his entire being, reducing him to nothing more than the sensation of Cecilia’s fingers filling his greedy, slutty hole as his orgasm washes over him, and how he wanted more, more, more-
“Ah, ah, ahhh~❤!” Cecilia lifted her mouth from Lucius’s, just in time for an utterly whorish sound to spill from his lips. He arched his back, vision whiting out.
It took several seconds for Lucius to come back to himself. Several seconds, for his senses to return, for his walls to loosen their death grip on Cecilia’s fingers.
As he caught his breath, Cecilia abruptly pulled her fingers out. The rough motion had him wincing. He turned his head towards her, staring blankly as Cecilia sat back on her haunches between his thighs; hands pumping her enormous jet-black horsecock.
Lucius’s lower half throbbed, achingly empty. His breathing deepened, blood roaring in his ears.
He wanted… he needed-
“Lucius,” Cecilia breathed, vibrant red eyes shining. “Show me how you want me. Beg for your big sister’s cock.”
Big sister. Big sister…
Big sister’s cock…❤?
Lucius’s eyes dilated.
No, something inside him - defiant and proud - screamed. But it was quickly overshadowed by the sound of blood roaring in his ears, driven wild by Cecilia’s cum, reminding him of the throb of his hole, aching to be filled. His gaze lowered to Cecilia’s pelvis. Staring at her fat horsecock. It drooled; iridescent precum slipping down the slab of musky girlmeat. His eyes followed its path, down the bulge of large veins and over hairy balls, disappearing into a coarse bush. His world narrowed down to one thing and one thing only:
Big sister’s cock.
Big sister’s horsecock.
Big sister’s fat cock, her cock, her cock~❤
“P-please.” Lucius choked out. “Please let me have your cock, big sister…❤”
The plea broke something in Lucius. He swayed, lost to his desire for something to fill his greedy hole. Tears slipped down his cheeks as Cecilia’s lips twisted cruelly. “Tsk. Be more specific, brother. Tell me you wanna become my bitch.”
Lucius whimpered. Embarrassment coursed through Lucius’s veins but lust took precedence He rolled onto his stomach, lifting his hips high into the air. Thumbs dug into his asscheeks, pulling them apart, exposing his hole. His virginal and unused pink, puckered hole.
“Please, big sister,” he whined, wriggling his hips. “Please f-fuck my hole with your big cock~ use me as your cum toilet. Please-”
He squeezed his eyes shut. “Please turn me into your bitch~❤”
Behind him, unseen by Lucius, Cecilia straightened. Her smirk widened into a triumphant grin. “As you wish.” she purred.
Taking hold of his hips, Cecilia rammed into Lucius.
A scream ripped free of Lucius’s throat.
It burned. It hurt.
There was no describing the sudden fullness in his lower half; his muscles stretched beyond their capacity. It felt like Cecilia’s cock was reaching his throat. He gasped, struggling to breathe with his insides forced to accommodate a horse’s cock. It was too big for him. His body was too small to handle her size. And yet- Cecilia persisted. He could feel her grunting with effort as she squeezed every last inch of her horsecock into his hole. It should be painful. Instead, Lucius moaned. He moaned and shivered with each successive inch forced into him. Brain melting out of his ears until-
Ah~❤
The last inch of cock slipped into him. Lucius’s mouth went slack, fingers clutching the bedsheets, as his pathetic balls tightened
Her cock- his big sister’s cock - was pressing against something deep inside of him. Glans rubbing and caressing that little bundle of cells in his hole. And it felt so good~❤
Vision going white, Lucius felt his pathetic balls tighten before a sticky fluid splashed onto his belly. His own laid untouched beneath him. His walls squeezed down around Cecilia’s horsecock. She moaned. “Hrngh- what a tight, slutty hole-! Is this what you’re really like, little brother?” she laughed breathlessly to herself. “If I’d known, I would have done this ages ago.”
Lucius’s sister reached out, her hand creeping beneath his groin. He mewled, feeling her hand stiffen as it brushed over a very soft and spent organ. “Did you just cum from being fucked in the ass?” She asked, her tone disbelieving.
Lucius merely whined, wriggling his hips and squeezing the cock inside of him. Pleading with her to move.
“You did, didn’t you?” Cecilia laughed. “What a cockslut.” She pulled back, then rammed her hips forward once more. Watching as Lucius’s back curved as he moaned lewdly. “No wonder I was turned into this demon.” Thrust. “This disgusting pubic hair, this smell, this nasty horsecock-” Her voice deepened into a growl.
Thrust.
Sharp claws dug into Lucius’s ass. “It’s all because of you, isn’t it?!”
Thrust.
“Answer me, slut!”
Smack.
Lucius squealed, his left asscheek stinging. “M’ sorry~!” he slurred. “I’m sorry for being such a greedy cockslut that I gave my sister a cock~❤”
Cecilia scoffed. “I knew it.”
A heavy weight bore down on Lucius, pinning him to the bed. Soft, pillowy breasts pressed against his back - a stark contrast to the hard cock picking up speed as it hammered into his hole. Lucius moaned. “Giving your own sister this body…” Cecilia’s lips pulled into a snarl. “You better take some responsibility, whore!”
Claws gripped his hair, jerking his head up. Lucius cried out, cock twitching at the rough treatment. “From now on,” his big sister breathed. “You’re my bitch. My cumslut. Understand?!”
Smack.
Lucius nodded frantically. “Your cumslut, yours~❤!”
“No one else will touch this slutty body. Only me!”
Smack.
Tongue lolling out of his mouth, Lucius agreed mindlessly. “Only big sister’s penis! Only big sister~❤❤”
Cecilia chuckled. “Glad you understand, little brother. Now,” Her eyes flashed. “Come.”
“Uh, ah, ahhhh~❤❤❤!”
Lucius screamed, the sound ripping from his throat, as his orgasm took him. Every single nerve in his body, from his erect nipples, to his toes, lit up; oxytocin and dopamine overloading what little remained of his brain. Inner walls flexed and milked the hard cock pouring load after load of hot, sticky seed into his belly. Hot, demonic cum that splashed against his inner walls, soaking him in corruptive miasma.
Corruptive, demonic miasma that was absorbed by his walls, and coursed through his blood. Changing his cells and distorting his soul. Soon, his soft, flat chest curved outwards, forming small tits. Thin hips widened, cock shrinking - becoming a micropenis, soft and useless. Small testicles shrank further, virility utterly snuffed out. Cute, stubby horns grew from Lucius’s skull and Lucius mewled, his own heart-tipped tail waving behind him enticingly.
“Big sister… ah❤!” He mewled as Cecilia pulled out and turned him around. He whimpered in confusion - hole terribly, achingly empty - nuzzling her hand as she cupped his cheek. Big, pink eyes blinked at her . A forked tongue slipped out of his mouth and licked her palm. “Big sister… cock❤?” He pleaded.
Cecilia kissed him, smirking as her sweet little brother eagerly leaned into her. “Patience, Lucius… we have all the time in the world.”
Lucius smiled, cheeks flushed. He nodded obediently. Maybe later - much later - he would realise what had happened. What his sister had done to him. But by then, it would be too late to escape her grasp. Her prison of love and cock and blood would bind them together, forever.
For now, the oblivious succubus opened his arms and legs, welcoming his beloved big sister into his hole, his body-
-And the two relished the long night that awaited them.