Chapter 1: Caster's Brutal Corruption of Saber
The air in the dungeon was cold and carried the taste of damp earth and old iron. Torches guttered in their brackets, throwing long, shuddering shadows across the rough-hewn stone. The chains lining the walls weren’t for show; Saber felt their ghostly pressure on her wrists and ankles even though no physical bonds held her. A shimmering, violet field of light—Caster’s magic—pinned her against the cold wall, a crushing, invisible weight against her chest.
She was barefoot, her usual armor and dress vanished, leaving her in only her smallclothes. The chill of the stone seeped into her skin. She held her head high, the line of her jaw rigid, but a fine tremor ran through her exhausted muscles.
Footsteps echoed, slow and deliberate, from the corridor outside her cell. Caster appeared in the archway, a silhouette against the flickering torchlight. She leaned against the stone frame, her light purple hair almost glowing in the dimness. A small, knowing smile played on her lips.
“Comfortable, King of Knights?”
Saber said nothing. She fixed her striking eyes on a point just beyond Caster’s shoulder, a portrait of defiance.
Caster pushed off from the wall and strolled closer, her bare feet silent on the stone. She wore a simple, dark robe, loosely tied. “The silent treatment. How very noble.” She circled Saber, her gaze analytic, cold. “All that power, all that legendary grace… reduced to this. It’s almost a shame.”
“Your theatrics are pointless, Caster,” Saber said, her voice low and strained from the magical pressure. “My Master will find me.”
“Your Master.” Caster laughed, a soft, musical sound that felt utterly wrong in the gloom. “The boy? The one you’re so dutifully sworn to? Tell me, Saber… does he know how you really feel?”
Saber’s eyes flickered. “I do not understand your meaning.”
“Don’t you?” Caster stopped in front of her, so close Saber could smell her scent—sweet like herbs and ozone. “The perfect servant. The loyal knight. But I can see the cracks. The… wanting.” She reached out, a single finger tracing a line from Saber’s collarbone down to her sternum. Saber flinched, the first real break in her composure.
“There is no crack in my dut
y,” Saber hissed, but the words caught in her throat as Caster’s robe loosened, revealing the smooth, pale skin of her stomach and the shocking, unnatural fullness between her legs. “Duty is just a prettier chain.” Caster whispered, her form shimmering as the massive, foot-long length of her futanari cock swelled into existence, pressing hot and heavy against Saber’s bare thigh. Saber recoiled, but the magical bindings held her fast, forcing her to feel every inch of that alien heat. “Let’s see what breaks first,” Caster murmured, her breath hot against Saber’s ear, “your loyalty, or your body.”
“Let’s see what breaks first,” Caster murmured, her breath hot against Saber’s ear, “your loyalty, or your body.”
A flick of Caster’s wrist sent a new, vicious pulse of magical energy through the bindings. It wasn’t a shove; it was a command written directly into Saber’s straining muscles, an inexorable, physical decree. Saber’s torso remained pinned to the wall, but a strained gasp escaped her as her legs, trembling with the effort of resistance, were slowly, ruthlessly forced apart. Her knees pressed outward against the invisible pressure until her stance was wide and vulnerably open, the chill of the dungeon air now a shocking intimacy against her inner thighs. Caster leaned into the space created, her own unnaturally heated skin nearly touching Saber’s, and smiled. “There. Now we can speak frankly.”
“Speak?” Saber spat, the word dripping with contempt even as her body trembled from the effort of keeping that terrifying heat from searing her skin. She threw her weight sideways, a desperate, grating shuffle of her bare shoulders against the unyielding stone, turning her face away. “The only words you’ll hear from me are curses.”
Caster’s laugh was a soft, patronizing echo. “We’ll see.” The magus leaned in, her unnatural length dragging a burning trail up Saber’s inner thigh.
The contact was a violation, a searing brand that made Saber’s breath hitch despite her iron will. "You flinch," Caster observed, her voice a conspiratorial whisper. "Your body understands the truth your honor denies." She applied a subtle, relentless pressure, not thrusting, but claiming the space, making her invasive presence impossible to ignore. Saber shut her eyes tight, a bead of sweat tracing a path from her temple to her jaw as she focused everything on the distant, fading echo of her Master’s call.
The distant call in her mind snapped like a frayed thread as Caster entered her.
A sharp, fractured sound escaped Saber’s lips—part gasp, part strangled curse—as the impossible, burning fullness enters her. Caster’s sigh was one of deep satisfaction, her forehead coming to rest against the cool stone beside Saber’s face. “There,” she whispered, her voice thick with triumph. “Your legendary strength will soon belong to me.”
The pain was a white-hot spear, tearing through discipline and focus. Saber’s head snapped back against the stone, a guttural cry ripped from her throat. Every brutal, sliding inch was a defilement of the contract she swore, a corrosion of her very legend.
“Your Master cannot hear you now,” Caster breathed, her hips settling flush against Saber’s, embedding herself completely. She was motionless, letting the sheer, shocking fact of the violation settle in. “This is a different kind of pact, Saber. One of flesh, not magic.”
Saber trembled, her golden hair sticking to her damp forehead. “I will… kill you for this.”
“Promises, promises.” Caster’s hand came up, fingers tangling in that golden hair, not yanking, but cradling her skull with horrifying tenderness. She began to move, a slow, deep roll of her hips that forced a choked gasp past Saber’s clenched teeth. “Look at you. The mighty king, unmade. I can feel your body betraying you already. It’s just anatomy, my dear. A biological imperative to… accommodate.”
“Lies,” Saber hissed, but the word was thin, brittle. A traitorous heat was building beneath the agony, a deep, shameful pulse that echoed Caster’s rhythm.
Caster increased her pace, the wet, rhythmic sound obscene in the silent dungeon. “Your loyalty is a chain to a boy who doesn’t know how to use you. I am showing you a far more ancient power.”
Saber’s vision blurred, the torchlight swimming into streaks of orange and shadow. Each thrust hammered not just her body, but her spirit. A low moan escaped her, and she hated herself for it.
Caster smiled, a real, radiant smile of victory. “There. Was that so hard?” She leaned in, her lips brushing the shell of Saber’s ear. “You’ll beg for him to never find you. You’ll beg for this, before the end.”
Caster’s lips curled into a wicked smile. “That boy,” she sneered, her voice dripping with contempt as she ground her hips forward, burying herself another devastating inch deeper. “Shirou.” She said his name like a curse, a bitter taste on her tongue. “He’s a child playing with a sword too large for him.” Saber cried out, a sharp, broken sound that echoed off the damp stones. “He doesn’t command a king. He stumbles after a ghost, all ideals and empty hands.” Caster’s rhythm became a brutal, punctuating hammer to each of her insults. “He is a cracked vessel, pouring everything out for nothing.” A particularly deep thrust stole Saber’s breath. “And you,” Caster whispered, her breath hot, “you are the prize he doesn’t even know how to claim.” Saber’s vision swam, the torchlight blurring into tears she refused to shed. A traitorous, shivering tension was coiling tight in her abdomen, a visceral counterpoint to the tearing pain. Her own body was turning against her, responding to the relentless, invasive heat. “He will never make you feel this,” Caster groaned, her own control fraying as she chased her climax. “He will never know you this way.” The words were a final, cruel twist of the knife. Saber’s head dropped forward, her golden hair a curtain hiding her shattered expression. A low, shuddering sob was torn from her chest, the sound of something pristine fracturing. It was a victory cry for Caster, who drove into that shuddering release with a triumphant gasp, claiming more than just Saber’s body in that moment.
It was a victory cry for Caster, who drove into that shuddering release with a triumphant gasp, claiming more than just Saber’s body in that moment. Caster did not pull away but remained buried within her, a permanent, claiming heat. “You see?” Caster panted, her voice ragged yet smug. She brushed the damp hair from Saber’s brow. Saber’s sob, a raw sound of utter defeat, caught in her throat. Caster moved again, a slow, insistent roll of her hips that was less about passion and more about demonstration. The friction sparked a new, shocking wave of sensation up Saber’s spine. Her back arched, not away, but into it, a traitorous curve of her spine. The sob twisted, warped by a sharp intake of breath that hitched and broke. It escaped her lips as a moan, low and ragged and full of shame. She snapped her teeth together, trying to bite the sound back, but it was too late. Caster heard it. “There it is,” Caster whispered, her voice a silken triumph. She adjusted her angle, seeking that spot again with predatory precision. “Your body is wiser than your pride, King of Knights.” Saber squeezed her eyes shut, but the darkness only magnified the feel of it, the deep, full stretch, the building pressure that mocked her resolve. Another moan, softer this time, was punched out of her with the next thrust. Her hands, pinned by magic, clenched into impotent fists. Her head lolled against the stone, all fight draining away with that audible proof of her corruption. Caster laughed, a light, breathy sound of pure satisfaction, and kissed her shoulder. “Now we begin in earnest.”
Caster finally withdrew, the sudden absence inside Saber feeling almost as violating as the presence had. Saber’s legs, released from the magical compulsion, buckled, but the bindings on her wrists held her upright, forcing her to dangle from her arms. She hung there, head bowed, breathing in ragged, wet gasps that echoed off the stones.
Caster stepped back, observing her handiwork with a critical, satisfied eye. “The first lesson is always the hardest,” she said, her voice casual, as if discussing the weather. She snapped her fingers, and a worn wooden chair materialized from swirls of violet light. She sat, crossing her legs. “Your body is no longer yours to command. It responds to me. Remember that.”
Saber said nothing. A single drop of sweat or something else fell from her chin and darkened the stone floor between her feet.
“The boy is searching,” Caster continued, idly examining her nails. “He and the Tohsaka girl are blundering through the forest above right now. Their panic is quite… palpable.” She looked up, her gaze sharp. “If I let you feel your connection to him right now, what would you feel? Shame, probably. You’d feel the stain of this on your shared magic. You’d be afraid for him to find you.”
“You will not break our contract,” Saber whispered, the words raw.
“I’m not breaking it.” Caster leaned forward. “I’m making you forget why it ever mattered.” She stood and approached again, her hand closing around Saber’s throat, not to choke, but to claim. “Let’s see if your body remembers its new allegiance before your mind does.”
Caster’s smirk was a blade in the dim light. She released Saber’s throat and took two steps back, her form shimmering with gathered power. “But first, a necessary interruption. Your would-be rescuers are becoming a nuisance.”
She flicked her wrist towards the dungeon’s ceiling. Two pools of shadow at her feet bubbled and coalesced into slender, faceless humanoid shapes wrought from scrap metal and dark mana. They dripped onto the stones. “Lead them on a merry chase through the western woods,” she commanded, her voice echoing with authority. “Make it convincing. Hurt them if you must, but do not kill the boy. Not yet.” The minions bowed their misshapen heads and streaked away like liquid night up the stairwell.
Saber tried to cling to the sound of their departure, a fragile hope. Caster’s attention returned to her, absolute and suffocating.
“Alone again,” Caster whispered, closing the distance. Her hand slid down Saber’s trembling stomach, fingertips tracing the tight, quivering muscles. “Where were we?”
“Don’t,” Saber breathed, the word a brittle thing.
“You’re right,” Caster said, her other hand cupping Saber’s cheek, forcing her to meet that captivating gaze. “Talking is wasteful now.” The magical field shifted, tilting Saber’s hips forward, presenting her anew. Caster’s length, still slick and heated from their first violation, found its place with a brutal, practiced ease. Saber cried out, a raw sound of re-opened shame.
Caster began to move, a relentless, deep rhythm. “Your Master is chasing phantoms in the dark,” she groaned into Saber’s ear, each thrust punctuating her words. “While I claim what he’s already lost.”
The words were a venomous seed planted deep with every punishing thrust. “He’s just a child,” Caster gasped, her own rhythm becoming erratic, driven by a malice that was both personal and profane. “A child with borrowed power and a hero complex.” She drove home her point with a sharp, twisting snap of her hips. Saber’s choked cry was the only answer. “He dreams of saving everyone.” Another thrust, deeper, stealing the air from Saber’s lungs. “But he can’t even save you from this.” Caster’s hand fisted in golden hair, yanking Saber’s head back to expose the pale line of her throat. She leaned in, her lips brushing the shell of Sabar's ear as she hit a devastating, slow rhythm. “A little boy like him could never satisfy you.”
The statement hung in the damp air, a toxic truth that seeped into the cracks of Saber’s resolve. A treacherous, full-body shiver wracked her, one that had nothing to do with the cold stone. Caster felt it—the involuntary clench, the faint, yielding tremor—and her smile was a victor’s smile. “You see?” she murmured, her pace becoming deliberate, almost gentle, a horrifying mockery of tenderness. “Your body is already learning.” Saber’s silence now was a different kind; it was the silence of a fortress whose gates had been breached, the defenders slain within. A single, hot tear finally escaped, tracing a clean path through the grime on her cheek. Caster kissed it away, her tongue catching the salt.
Caster kissed it away, her tongue catching the salt.
“See?” she breathed, the word warm and damp against Saber’s skin. “Nothing but biology.”
Then the tempo changed.
It wasn’t a slow, cruel grind anymore. It was a claiming. Caster’s hands slid from her hair to her hips, fingers digging in, finding a brutal new rhythm. No more taunts, no more whispered poison. Just motion, deep and piston-fast, the slick, wet sound of it filling the cell, louder than Saber’s ragged breathing. The magical bindings held her firm, making her a perfect receptacle for every driving thrust.
Saber’s world narrowed to the brutal, repetitive impact. The stone at her back, the heat spreading from her core, the unbearable friction that was now shifting, somehow, into something else. A coil, hot and tight, was winding itself in her belly, each snap of Caster’s hips tightening it a notch. She tried to clench her jaw, to lock the feeling out, but it was a floodgate buckling.
A broken moan escaped her, then another, higher, unwilling. Her head thrashed against the wall. She couldn’t stop it. Her body was climbing, muscles taut, nerves singing a traitorous song. The pain had blurred into a sharp, overwhelming urgency.
Caster’s breath was coming in sharp gasps now, her composure shattering. Her perfect, manipulative mask slipped, revealing raw, unadorned hunger. She drove into Saber with a frenzied intensity, her own sounds a mix of growls and ragged sighs.
“That’s it,” Caster choked out, her voice stripped of its cunning, reduced to pure need. “Come on. Let go.”
Saber couldn’t fight it. The coil snapped.
Her back arched violently against the stone, a silent scream on her lips as a wave of sensation detonated through her. It was seismic, obliterating thought, obliterating shame. Her legs trembled, her vision whiting out as spasms wracked her, her body clutching around the invader in a relentless, rhythmic pulse of involuntary pleasure.
That final, devastating clench tipped Caster over the edge. With a raw, guttural cry that held more triumph than ecstasy, she buried herself to the hilt and held there. Saber, still trembling in the aftershocks, felt the hot, deep pulse as Caster found her own release inside her.
For a long moment, there was only the sound of their mingled, ragged breathing and the drip of water somewhere in the dark.
Caster slowly slumped forward, her forehead resting on Saber’s shoulder, her weight a leaden, final claim. She withdrew, the motion slow, deliberate, leaving Saber feeling empty and horrifically used. The magical field vanished. Saber’s legs, useless, gave way immediately. She crumpled onto the cold, filthy stones, her body a vessel of trembling aftershocks and profound violation.
Caster stood over her, adjusting her robe, the picture of composed cruelty once more. She looked down, her gaze satisfied. “Clean yourself up. We have more lessons tomorrow.”
She turned and walked away, her footsteps fading into the dungeon’s gloom.
Saber lay curled on the stone, the cold a sharp contrast to the lingering heat inside her. She stared at the wall, seeing nothing. Her mind was a void, a scorched plain. But her body… her body hummed. A deep, post-storm stillness laced with the fading echoes of that cataclysm. Her muscles felt liquid, spent. A treacherous warmth still pooled low in her abdomen, a physical memory of the peak Caster had forced her over.
She tried to summon the rage, the royal fury that had defended Britain. It felt like a story about someone else. She tried to feel the scorching shame. It was there, but distant, muffled beneath a heavier, more terrifying truth.
Her body, the honed instrument of her will, had not just broken.
It had sung for its violator.
And in the silent, shameful dark, part of her was already afraid of wanting to hear that song again.