Fate/Charm of

the Devil Fae

This fic is inspired by Sticky Situation by  Professor Quill,   In Bloom by Flight of Fancy,  and to a certain extent Benefits of Saving a Veela by WD_ONeill . Please check them out.

Story Starts

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Ch. 0.3 Prologue

Quenching of the Sword

Disclaimer: Everyone here is at least 18 years of age. In Japan, students are typically 18 years old during their last year of high school. So all scenes of a sexual nature were done between consenting adults.

But to be safe, let’s add an addendum: this is a major AU. After Senior High School, students generally go to an academy for one to three years to take general subjects, think honestly about what they want, and prepare for higher education, or take vocational courses. This will take place during that period.

Shirou’s base level ' Charm’ is more akin to a Veela’s aura; it lowers the inhibitions of people who are attracted to Shirou, but ultimately, it’s up to them whether they want to act on it. It also depends on their general level of promiscuity.

In this story, both Sakura and Rin are fraternal twins, and I’m not going through the Illya-is-a-legal-loli route, nor will I ever—not that there’s any wrong with young-looking or petite adults.

Disclaimer 2 (For Patreon Staff): To avoid getting this chapter blocked and to skip the need to appeal. There will be no incest in this story. This chapter and the following chapter will involve Shirou x Sakura & Shirou x Rin, they just so happen to be in the same room. Nothing sexual will cross between Rin and Sakura.

And with a final powerful thrust that sent crackling electricity coursing through them both, a shrill scream of pure ecstasy tore from Rin's throat as Shirou buried himself to the hilt one last time this morning, his release erupting deep inside her heated core in thick, pulsing waves.

She collapsed forward immediately after the intensity peaked, her thoroughly used body utterly spent, consciousness slipping away like sand through an hourglass as complete exhaustion finally claimed her. Yet even in the depths of her total exhaustion, her face remained remarkably serene—peaceful, almost ethereal in the sunlight and the room's lighting—and you could discern the faintest satisfied smile playing at the corners of her kiss-swollen lips, a wordless testament to the overwhelming pleasure that had consumed them both.

Shirou remained suspended in that strange liminal space between physical exertion and deep satisfaction, his breathing still ragged and uneven despite several minutes of recovery, chest heaving with the effort of drawing air.

Though his cock still stood partially upright despite everything, glistening wetly under the room's ambient light with their mixed fluids, he forced himself to think clearly through the pleasant fog clouding his mind. Glancing towards the digital clock on the nightstand, he felt a mixture of genuine disbelief and wonder wash over him—had it really been about three full hours since they'd first started? Three consecutive hours of raw passion, of profound physical and emotional connection, of pushing themselves to the very brink of human endurance and beyond.

His immediate lust temporarily sated for the first time in weeks, he drew in a long, steadying breath and carefully crawled over towards the sleeping form of his best friend, who now lay peacefully beside him, her breathing deep and even in genuine sleep.

With movements far more tender and gentle than anything that had preceded them during their marathon session, he carefully flipped her over onto her back, arranging her limbs with solicitous attention to her comfort. Then, his touch impossibly gentle, he tucked a stray strand of sweat-dampened dark hair behind her ear, his fingers lingering for just a moment against her still-warm skin before he reluctantly withdrew, not wanting to disturb her well-earned rest.

Then he felt it—that unmistakable sensation of something impossibly smooth and warm coiling around his semi-hard member with deliberate, purposeful intent. For a split second, his tired mind conjured the image of Rin somehow stirring from her exhausted sleep, perhaps awakening with renewed hunger despite having just passed out, ready for yet another round when by all rights she should be unconscious for hours.

His heart quickened instinctively at the prospect, fresh anticipation flooding through his veins despite his fatigue. But as he lowered his gaze to investigate, the reality proved far different than his initial speculation. One of Sakura's distinctive dark tendrils had wound itself sinuously around his shaft with deliberate sensuality, the living shadowy ribbon writhing and pulsing against him with an almost hypnotic rhythm that sent fresh waves of pleasure spiraling through his oversensitive nerve endings and making him gasp.

The unexpected shock of it jolted him fully alert, his residual physical fatigue momentarily forgotten entirely in the face of this new development. He lifted his eyes from his lap to find Sakura standing at the edge of the futon, having abandoned her desk chair—her expression completely transformed into something altogether different from her earlier composed observation. Her normally serene face was flushed darkly with unmistakable burning lust, her breathing coming in heavy, deliberate gasps that seemed to mirror the overwhelming intensity radiating from her entire trembling being.

The careful arrangement of her long skirt had been abandoned entirely at some point; the hem now pinched haphazardly between its waistband, utterly forgotten in the wake of her overwhelming desire.

Her white cotton panties had been carelessly pushed aside, revealing the absolutely glistening evidence of her profound arousal—her swollen slit and visibly engorged clit laid completely bare to his hungry view, an explicit invitation written in abundant moisture and flushed pink skin that practically begged for attention.

She was touching herself, he realized with a sharp intake of breath, her slender fingers working rhythmically against her own nether lips with practised, deliberate motions clearly born of three long hours of continuous self-stimulation whilst watching him with Rin.

The evidence of her ministrations was evident in how thoroughly soaked she was. Then, in a movement that sent fresh waves of molten heat coursing through his veins, she brought those same glistening fingers up to her parted lips and began to suck on them slowly, deliberately, her intense violet eyes never once leaving his golden gaze—maintaining eye contact the entire time in a display that was frankly pornographic in its intensity.

Shirou found himself utterly transfixed, unable to look away even if he'd wanted to, as he followed the hypnotic journey of her digits. She drew them into her mouth with obvious relish, tasting her own arousal coating them, completely unashamed in her desire and desperate need. Her tongue worked visibly around her fingers, cleaning them thoroughly.

The sight was utterly intoxicating—almost as intoxicating as the dark tendril continuing its relentless, sinuous caress around his hardened length. The slick, warm pressure of the living shadow ribbon sent electric jolts racing through his nervous system with each deliberate pulse and squeeze, each new sensation making his breath catch sharply in his throat.

The tapered tip of the dark ribbon wrapped firmly around the sensitive base of his cockhead with perfect pressure, the sensation so intense it bordered on genuinely overwhelming, massaging the delicate ridge and his frenulum with an almost sentient understanding of exactly what would drive him absolutely mad with pleasure. The tendril moved up and down his full shaft with deliberate, torturous precision, each slow stroke expertly drawing involuntary gasps and groans from his lips.

The heady, thick scent of her arousal hung heavy in the air between them, musky and utterly intoxicating, mixing with the still-lingering smell of sex from his marathon session with Rin.

Not caring at all if she woke up Rin sleeping peacefully in an exhausted heap beside them on the futon, Sakura placed both hands on Shirou's shoulders with surprising force, her fingernails digging into his bare flesh hard enough to leave visible crescent-shaped marks in his skin.

Her normally serene face showed clear evidence of the strain of her three-hour wait, pupils dilated wide with desperate hunger as she pushed Shirou firmly down onto the bed with trembling hands that betrayed both her overwhelming need and her iron determination to finally have her turn.

"I've been waiting for three whole hours—I've been touching myself for that entire time," her voice came out hoarse and rough, nearly breaking on the words, each syllable dripping with barely contained need and mounting frustration.

The raw desperation threading through her normally soft tone made something twist deep in his chest—overwhelming desire mixed with genuine appreciation for her patience and restraint. "Look at what you made me do to myself, whilst you thoroughly enjoyed my sister."

It wasn't accusation exactly—more statement of fact delivered with breathless need.

Her hand moved back down between her thighs to her absolutely sopping pussy, fingers sliding easily through the abundant wetness she'd worked herself into during her long vigil of watching and masturbating. A long, viscous trail of slick arousal was pouring steadily down both her inner thighs in thick rivulets, catching the morning sunlight filtering through the window and making her pale skin glisten as though she'd been deliberately painted with liquid desire.

"Saku… I…" Shirou began, but his face broke into a genuine smile of understanding, affection and anticipation as he reached up to Sakura with both arms, bringing her down into a warm, sincere embrace despite their sexually charged position.

"That was completely my fault—I should have alternated between you both instead of getting lost in Rin for three straight hours. I didn't really think clearly once we started." His smile widened, becoming almost playful despite the intensity of the moment. "Let us enjoy each other properly this time. You've more than earned it."

They both separated slowly from the tender embrace, Sakura's expression softening briefly with relief and gratitude before the lust returned full force. Her sopping wet hand traced the line of his face with a reverent, possessive touch, her fingertips leaving faint trails of moisture as they followed his jaw line, trailing upward until her fingers finally reached his parted lips. Shirou reached up without any hesitation to draw her offered digits into his mouth, actively welcoming the taste, wanting to experience her fully.

The flavour exploded across his tongue in a rush of sensation—her musk, rich and intoxicating, mingling perfectly with the sweet and slightly salty notes of her prolonged arousal that had accumulated over three hours of patient, desperate waiting. It was distinctly different from Rin's taste, uniquely Sakura, and he found himself eager for more.

His tongue began lapping enthusiastically at the slender digits filling his mouth, swirling around them deliberately, tasting every bit of her essence coating them. The intimate flavour made his head spin pleasantly as Sakura moaned loudly above him, clearly pleased by his eager reception. Her free hand reached down between their bodies to where his cock was still thoroughly encased in the writhing ribbons of her magecraft, the tendrils pulsing and tightening rhythmically with her mounting excitement.

She took a long moment to position herself properly above him, straddling his hips with her thighs spread wide, her movements deliberate and purposeful despite the obvious desperation thrumming through her veins like electricity.

Shirou held his breath in keen anticipation as she settled her full weight into position above him, rising up on her knees, his mind reeling from the sheer intensity of everything that had led to this precise moment—the intervention, Rin's three-hour marathon session, Sakura's patient observation and continuous self-stimulation throughout.

He could feel the swollen tip of his cock brushing teasingly against her soaking wet entrance, the contact making them both shudder. Her abundant arousal coated him thoroughly with the slick liquid evidence of hours spent alone with her overwhelming need, her fingers working herself into an absolute frenzy whilst he thoroughly ravaged her twin sister mere metres away on this very futon.

The sensation was exquisite torture, making every muscle in his body tense with building anticipation and barely restrained desire. He wanted to thrust up immediately, to bury himself in her heat, but he forced himself to wait, to let her control the pace of entry.

But then Sakura moved decisively, and all rational thought dissolved entirely into pure sensation.

With one smooth, deliberate motion born of three hours of desperate pent-up need, she drove herself down onto his full length without any hesitation, taking every last inch of his considerable size as she slammed her hips flush against his with a force that knocked the air explosively from both their lungs.

The sensation was utterly overwhelming—the scorching wet heat enveloping him, the impossible tightness of her virgin passage gripping him, the profound completeness of their joining—and Shirou couldn't suppress the raw, guttural groan that tore unbidden from his throat. His hands gripped her waist instinctively, fingers digging possessively into her soft flesh as he actively met her passion with his own, driving his hips up powerfully to meet her downward motion, matching her desperate intensity halfway.

The overwhelming pleasure of finally being filled completely drove Sakura to new heights of burning lust, her normally serene expression shifting dramatically into something far more primal and uninhibited—raw need written across every feature. The thick, heavy scent of her arousal hung oppressively in the air around them, mingling potently with the faint tang of fresh sweat and the lingering musky evidence of sex, of their bodies pressed together in the most intimate way possible.

Shirou could feel every single inch of her wrapped tightly around him—the slick, scorching heat of her tight cunt clenching rhythmically around his entire length, her inner walls rippling and fluttering as they struggled to accommodate his size. He could feel the way her thighs trembled visibly against his hips as she ground down with slow circular motions, experimenting with the angle.

The wriggling tendrils of her magecraft remained coiled possessively around the base of his shaft like living bondage, pulsing and squeezing in perfect synchronisation with her internal contractions, adding yet another overwhelming layer of stimulation to an already intense experience.

It was too much, far too overwhelming for his overstimulated senses—her intoxicating scent filling his lungs with every ragged breath, her unique taste still coating his tongue from sucking her fingers clean, the absolutely maddening friction of her riding him with reckless, desperate abandon, chasing the pleasure she'd been denied for three agonising hours.

Any coherent thoughts barely managed to form in his lust-hazed mind before Sakura slammed her hips down again with renewed force, driving him impossibly deeper and forcing a choked groan from deep in his throat. Her nails dug sharply into the muscles of his chest, leaving visible crescent-shaped marks in their wake as she leaned forward aggressively, bringing her flushed face close to his, her panting breath ghosting hot against the sensitive shell of his ear.

"You feel so good inside me, Shirou," she purred breathlessly directly into his ear, her normally gentle voice now dripping with raw satisfaction and possessive hunger. She blew softly against the sensitive skin, making him shiver, then nipped playfully at his earlobe with her teeth, the slight sting mixing deliciously with pleasure.

Her full breasts—noticeably larger than Rin's more modest chest—brushed repeatedly against his chest with every enthusiastic bounce of her body, nipples pebbled rock-hard and sensitive from hours of arousal, the stiff peaks dragging across his skin.

When he dared to glance down between their joined bodies, he could see the absolutely erotic way her swollen cunt swallowed him whole with each downward movement, her pink flesh glistening wetly with her abundant arousal and stretched impossibly taut around his thick cock—the dark tendrils not leaving his shaft not giving him respite even as he pulled back, the rest still writhing within her.

The obscene sight of her lips gripping him, of his shaft disappearing into her body again and again, nearly undid him completely—threatened to push him over the edge far too prematurely.

He was drowning in her—completely lost in the way her slick yet tight inner walls fluttered and clenched almost continuously around him with each movement, still adjusting to the intrusion. He was lost in the desperate roll of her hips as she sought the perfect angle, experimenting with what felt best. He was lost in the way her voice cracked beautifully on his name as she chased her own pleasure with single-minded determination, finally taking what she'd waited so patiently for.

The shadow tendrils coiled around his base tightened their grip suddenly, writhing like living things with minds of their own. Shirou swore he could feel them extending inside her as well, somehow, the magical construct dragging against his sensitive cock with every thrust and creating sensations he'd never experienced before—something beyond purely physical pleasure.

Sakura's breath hitched sharply at the sensation, her riding rhythm faltering for just a second before she redoubled her efforts with renewed determination, riding him with even greater fervour than before, chasing the building climax.

"Come for me," she demanded breathlessly, her voice taking on a commanding edge despite her obvious desperation. Her nails scraped deliberately down his chest, leaving angry red trails in their wake. "I want to feel you—all of you filling me completely."

And Shirou found himself completely unable to resist her breathless demand, his curse-driven body responding to her words as though they carried the weight of absolute command that his lust-hazed mind simply couldn't refuse. His large hands tightened their grip on her hips almost bruisingly, helping to drive her down harder as he thrust powerfully up to meet her descending motion, their bodies moving together in increasingly frantic, desperate rhythm as they both raced toward the edge.

The pleasure built rapidly between them, spiralling higher and tighter with each collision of their hips until—with a strangled, guttural groan torn from deep in his chest—he came explosively hard. His release erupted deep inside her passage in thick, powerful pulses, flooding her womb with his seed just as he'd done to Rin earlier.

Sakura cried out sharply in triumph and pleasure, her own intense climax triggered immediately by the scalding feeling of him filling her so completely, her inner walls clenching and rippling rhythmically around his spurting cock as wave after overwhelming wave of pleasure crashed through her trembling body. The shadow tendrils pulsed in tandem with her orgasm, tightening and writhing as though they too were experiencing the release.

She collapsed forward bonelessly onto his chest immediately after, both of them panting heavily in the aftermath, their sweat-slicked bodies pressed intimately together in satisfied exhaustion.

For a long moment, neither spoke or moved, simply basking quietly in the warm aftermath of their intense joining—Sakura finally thoroughly satisfied after her agonizingly long three-hour wait, and Shirou marvelling distantly at how different she felt from Rin in sensation and rhythm, yet equally perfect and satisfying in her own unique way.

The shadow tendrils slowly unwound from his softening length, retreating back into Sakura's body like living shadows returning home after completing their task. She shifted slightly atop him, settling more comfortably against his chest without withdrawing completely, seemingly content to remain intimately joined for now.

Her breathing gradually slowed from frantic panting to something deeper and more measured, the desperate edge finally leaving her expression as deep satisfaction and peaceful contentment replaced the frantic need that had driven her for the past three hours.

Sakura then pushed herself up as she hovered above Shirou in the aftermath, bracing herself on her hands, their eyes locked intensely with each other, their breaths still warm and ragged as they panted heavily from the sheer intensity of what they'd just shared.

Her violet eyes were beautifully glazed with lingering satisfaction and wonder, whilst his amber gaze held a mixture of amazement and deep contentment. The air between them felt thick with profound intimacy, charged with the echoes of their passionate joining, the world narrowed down to just the two of them in this perfect moment.

"I can't believe Sakura's secretly a complete freak," a teasing voice cut sharply through their private moment, shattering the bubble of intimacy. Both their heads turned simultaneously towards the source—Rin, who was now clearly wide awake and, judging by her knowing smirk, had been conscious for some time, possibly the entire duration of Sakura's turn.

She lay casually on her side with her head propped up on her knuckle, her elbow braced against the rumpled futon for support, one leg curved elegantly over the other that stretched out languidly behind her, her free hand resting with casual possession on the curve of her bare hip. Her expression was one of amused satisfaction mixed with mock disapproval, as though she'd been thoroughly entertained by the show her sister had put on but felt obligated to comment.

"Well, that's certainly one creative way to use that particular brand of magecraft," Rin continued with a casual shrug.

Just as Sakura opened her mouth to respond—likely with some embarrassed protest—someone knocked firmly on the fusuma, the sharp sound followed immediately by a muffled but cheerful voice filtering through the thin paper barrier.

It was Taiga's familiar enthusiastic tone, unbothered by what she surely knew had been happening. "I've placed some lunch for everyone outside the door, along with a large canister of water, and Runeas specifically sent you lot some of those stamina potions she's been brewing—the ones from that wand wizard recipe book! She said you'd probably need them!"

A somewhat breathless, chorused "thank you!" from the exhausted trio followed in ragged unison as they heard Taiga's footsteps gradually grow softer and softer, fading as she walked away down the corridor, mercifully leaving them to their privacy once more.

Rin simply shrugged again as she stood up from the futon with fluid grace despite her earlier exertions, stretching out the kinks and working the lingering stiffness from her well-used muscles with unselfconscious movements.

She walked towards the fusuma completely nude, utterly unbothered by her nakedness, her arse cheeks jiggling enticingly with each confident step. She knelt smoothly beside the door, sliding it open just enough to reach through the gap, then dragged in several laden trays of food, a large metal canister beading with condensation, and a polished wooden case filled with neat rows of small glass bottles glowing faintly with magical light.

"Here, catch." Rin turned to throw a vial across the room towards Shirou with casual precision, her modest breasts jiggling noticeably from the sudden throwing motion, drawing his eye despite himself.

Shirou plucked the bottle deftly from the air despite his distracted state and lingering post-orgasmic haze, then looked down curiously at the clear vial. It was filled with a viscous, pearly-white substance that sloshed gently. For some inexplicable and rather unfortunate reason, the potion's appearance resembled uncomfortably the copious fluids he'd been shooting for the past few hours. However, this magical concoction was considerably more fluid and shimmered faintly with silver-blue magical energy, marking it as Runeas's work.

"I'm absolutely sure Sakura would need that desperately after all that enthusiastic effort," Rin commented matter-of-factly, as though discussing something as mundane as the weather rather than her sister's sexual stamina. "She's been masturbating continuously for the past three hours whilst waiting impatiently for her turn, after all."

At the quizzical looks of surprise from both Shirou and Sakura—clearly startled that she'd been aware of such specific details—Rin protested somewhat defensively, "Hey, I can be perfectly observant of my surroundings whilst simultaneously being in the middle of overwhelming lust and mind-blowing ecstasy. It's called multitasking." She paused, then added with pointed accusation, "Besides, Shirou just doesn't relent once he gets going, nor did he give me any time whatsoever to tap out or catch my breath properly."

For some inexplicable reason, Shirou felt the sudden urge to look away in embarrassment at this casual revelation of his curse-enhanced stamina and the implicit admission that he'd been rather relentless.

His cock was still buried deep within Sakura's depths, remaining surprisingly firm despite having just climaxed, her radiating internal heat surrounding his member comfortably, almost possessively, as if his length was meant to remain there, as if her body had been specifically designed to accommodate and keep him.

But then the vial was snatched swiftly from his distracted hand as Sakura tipped it decisively over her mouth with determination, swallowing the potion's contents in one smooth, practised motion.

Before he could react, she immediately mashed her lips desperately to Shirou's in a passionate, demanding kiss that stole his breath. Their tongues battled fiercely for dominance as the stamina potion's powerful restorative effects began coursing rapidly through her system, reinvigorating her exhausted body with magical energy.

Rin simply shook her head with fond exasperation at their continued unrelenting enthusiasm, clearly amused despite her dry tone. She brought the laden food trays over to the low chabudai table, setting them down carefully, then grabbed Shirou's abandoned laptop and headphones from where they'd been left forgotten on the desk earlier. She plopped down comfortably beside the chabudai with a satisfied sigh, crossing her legs beneath her, and grabbed a pair of chopsticks from the tray.

Rin drank down her own vial of the stamina potion in one practised swallow, feeling the revitalising magic spread like warm honey through her thoroughly exhausted muscles, erasing the pleasant ache. Then she grabbed a piece of perfectly fried tofu agedashi, golden and glistening, and placed it carefully atop her still-steaming bowl of white rice. She began eating her late lunch with apparent contentment, chewing thoughtfully whilst she browsed the internet for something entertaining to occupy herself with.

Meanwhile, numerous additional tendrils of Sakura's shadow magic spawned from her body with renewed vigour as the stamina potion worked its powerful restorative effects, dark ribbons emerging like blooming flowers. Shirou suddenly pushed Sakura down onto her back with determined strength, reversing their positions, his miraculously still-hard cock remaining buried deep within her welcoming heat throughout the movement.

Now on top and firmly in control of the pace, he began thrusting into her with reckless abandon, driven by the curse's primal need that simply wouldn't be denied. Sakura's tendrils were back immediately with their writhing, sensual movements, wrapping possessively around both their bodies and penetrating her most sensitive places, the magecraft amplifying their shared pleasure and building ecstasy in waves of delicious, overwhelming sensation.

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END

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