Muzan Demon Slayer - Blog Posts

Half Blood | Muzan Kibutsuji x fem!reader

Warnings: NSFW, MDNI, TW! YN does get assaulted, mentions of blood, drinking blood, gore, how many times do I mention claws? Oral fem!receiving, fingering, kissing, breeding kink, virgin sex, creampie, and overstimulation.

Word Count: 4.9k

a/n: guys this started off as a quick break from a Sanemi fic I'm working on (keep in mind I think short fics are no longer than 3k) and here I am... with a way longer fic than I intended and something I actually want to expand on in the future. It was a lot of fun to write this so I hope you enjoy it <3

“You,” His pink irises are illuminated by the moon high in the night sky. The blood within your body cools as you stare back at the man who stored your fate. His inky black hair flows down his shoulder in waves. A deep blue yukata loosely hung on his frame. “I’ve been watching you.” Muzan growls, edging ever closer to where you stood. His pointed canines glinted in the light, his nails sharp and ready to claw at your jugular. The demon king rolls his tongue along the tips of his teeth, studying you carefully. Was he deciding whether or not to feast upon your flesh?

He had never seen such a creature as yourself. Your skin was glowing, soft, and supple. The lavender color yukata covered most of your body, a delicate pattern of white flowers spanning the kosode fabric. Your obi was white with purple vines flowing around it. You wear simple white tabies paired with purple strapped zori. Elegance and grace radiated from you. He could smell the wisteria perfume in your hair. 

It was strange, you were a confrontation to the world he wanted to live in – yet something he could not tear his eyes away from. Here you were, standing in front of him without fear. He rather thought it would be better fun if you were afraid, he did so enjoy the chase. Though, there was – of course – a reason you relented in running away from him. Your eyes were stormy, eclipsed by thousands of emotions. That’s when a different smell, that had not yet hit him, tickled his nose. Blood, and not just any blood. You had the blood of a demon in you. Your stern, furrowed brows, with the revolting smell of wisteria burning his nose. You confused him. “What are you?” He purs out, not sure if what would come out of your mouth would be a lie or truth. He could always figure it out for himself one way or another. 

Your lip ticks, a show of annoyance you’d yet to master. The man in front of you knew, he could smell it, of that you were sure. Yet, he dared ask. What are you? You’d been told many times what you were. An abomination. A curse. A monster. “Are you not the demon king?” You spit back, growing angry. Would the other half of you reject your existence as well? You had hoped at least the demons would have the scarce bit of comradery running through their systems. Muzan’s brows lift, then knit together. Did he need to answer you? After all, he could easily swipe at your neck to kill you for being so insolent. The eager need to hear what you had to say captivated him though. 

When the man does not answer you tut, crossing your arms over your chest. “Here I thought the mighty demon king would be able to tell me apart from the rest.” You shake your head, laughing stiffly into the night. In a flash Muzan has you pinned to the trunk of a tree. Splinters etch toward your face from the very force of his hand. His muscular body cages you in and it takes you a moment to realize how your body aches to be near him. 

“I can smell you,” He mutters, squinting his beautiful eyes like he couldn’t quite distinguish what he was looking at. “You assault my senses, it’s driving me mad. There’s something different about you.” Muzan had first observed you walking in your village one evening, the way people sneered and cowered at your presence intrigued him. He found himself looking for you every night, wondering what your story was. These villagers were shunning you. He wished to know why such a pretty thing as yourself would be outcasted in her own village. “You smell like me, yet you are not. So I ask you again, what are you?” His voice is low, edging on the precipice of anger. 

You do not yield in holding his gaze. “I am you, yet I am not. Born of the sun and moon. A half-blood.” 20 years ago your mother found herself in the entertainment district, serving the pleasures of others. A man came to visit her on multiple occasions. Eventually, the two ran away together. Sharing in love and secrets. Your mother was a demon and your father a local carpenter. How you were able to be conceived was a mystery, even to them. They lived in peace, until one night. The villagers had finally seen through your father’s lies, storming their house. They slaughtered both of them and assuming you were a child taken captive, they whisked you away to a widowed mother. As you grew it was obvious where your origins lay, yet no one in the village dared to lay a hand on you. 

Muzan lets his gaze drop to where your heart pulsed, bouncing the skin of your jugular. “You are human and demon?” Something pulled tight in his chest. Could you walk in the sun? Did you regenerate? Were you the answer to his plight? “You are radiant.” He cannot stop the words from falling past his lips. Your eyes light up with recognition, acceptance, and for a moment your past falls away. He had the ever-growing urge to sweep you away. Your very existence was tantalizing to him in the least. He tilts his head, wrinkling his nose at the obscure way you smelt. 

Your eyes settle on the way he reacts to you, wondering if he’ll take you away someplace. Some place away from these villagers who had slaughtered your parents who just wanted to live in harmony. They did not deserve to die and you did not want to live one more second with their murderers. Muzan wanted to take you, but he couldn’t. Not yet. You were so fragile. If he were to touch you he would fear you would break on the spot. “Are you going to take me away from this place?” You whisper, hopeful tones floating to Muzan. He swallows something deep and thick. 

Muzan backs away from you, eyes tensing. “No.” He replies softly. He could not take you into his den, the other demons were too stupid to realize how precious you were. You would be dead within seconds. The line between your brows hardens again as his words hit you. 

“No? Why not? Am I not good enough for you?” Your voice is rising. You sound like a whining child who hasn’t gotten their way. Muzan winces at the obvious pain seeping into your voice. You were nothing like he’d ever seen before. Something beautiful, a miracle in his eyes. Therefore, he did not answer you. He simply faded back into the shadows. With his disappearance, your hopes and dreams faded as well.

—

The next time you see Muzan is two years later. His hair is shorter than you last saw it, the curls kissing the nape of his neck. This neat look couldn’t contain the loose curls that framed his face. A starched white collar shirt was tucked into an ornate waistcoat. He looked utterly different, yet he was your Muzan. He had the same eyes, the same far-off look, and on top of that, you could practically taste his scent. It was overwhelming, crushing even, but in a way, you enjoyed the rush. 

It was also a fact that you had escaped your village after one of the men tried to see how strong a half-blood was. He told you he was turned on by how revolting you were and he would take you as his wife in duty only. Until then you had never seriously thought about killing a human. The realization was both terrifying and freeing. So you fled to the entertainment district, living off of what you could at the Kyogoku House. There were so many smells here. Food, humans, sex, and demons. 

You worked under a beautiful oiran, and you could tell… she wasn’t human. Part of you wanted to become friends with her, but if she hadn’t reached out for the sake of commonality, you didn’t think there was a chance of any other relationship than servant. 

Muzan’s brows furrowed. He had come to visit Daki and yet your scent prosecuted his brain. Ever since he left you in the forest that day he had been thinking of a way to retrieve you. You were too precious to let out of his sight again. This time he would secure you. He could feel his blood boil at the thought of you living in the Ukiyo. Kyogoku House was well protected, but anywhere without him wasn’t safe for you. Were you being used by men far beneath you? Muzan had never felt such rage toward the thought of men touching a woman. He often indulged in watching, humans were ever so entertaining – but you weren’t human. You were one of his and he swallowed harshly at the fact that you weren’t only his. 

He brushes past some of the lower-ranking courtesans, his eye twitching at their giggles. You watch from afar, the familiarity of his back etching a cold ache into your heart. He would leave again, of that you were sure. You hug the fresh sheets to your chest, making your way to the linen closet down the hall. “Ah, YN, I’ve been looking for you.” The Okaasan Omitsu stands before you. She has a cunning sneer behind the kind smile she wears. 

You bow, storing the sheets away before turning your full attention to her. “Yes Okaasan?” You can smell the evil intent behind this woman, it makes your stomach sink. 

“You wouldn’t mind doing me a favor would you?” She uses the word favor like you’d have a choice. She is the Okaasan after all. It’s like she thinks you’re some stupid girl that will follow whatever she says. Using the word favor is a manipulation tactic and if you were a naive girl, you would be eating out of the palm of her hand. 

You tilt your head to the left, plastering a fake smile of your own onto your lips. You knew anything out of your mouth except ‘yes Okaasan’ would make things harder for yourself. So with all your better judgment pushed aside, you say exactly that. 

Her eyes gleam. “Thank you, my dear. If you will kindly follow me.” She walks back up the hall, toward one of the private Ozashiki rooms. You glance around, nerves settling into your bones. You couldn’t be headed into one of these rooms, you weren’t even a kamuro. You were just an older shinzō. 

She stops in front of the panel, a cruel smile lifting the corners of her mouth. No, please, not this. “You are very blessed my dear, one of our chūsan is interested in you.” She slides the door aside and sitting against a wall smoking a pipe is a middle-aged man. Cushions are scattered around the floor and a twisted smirk plays with his mouth when he sees you. Okaasan bows then slides the door shut behind you. 

The room was stifling, the smoke choking out any of the senses you had. It was dizzying. “Mmm, you’re a lot older than I thought.” The man sneers, setting his pipe down. The fog of opium seemingly wraps around your throat, making it hard to breathe. “But you’ll do.” He laughs, patting the cushion next to him. “Why don’t you come a little closer?” He offers. Your body tenses. You were in danger, of that you were sure. You were not willing to give your virginity up to such a man but if you denied him the right to your own body, there would be outrage. You swallow, tentatively kneeling on the cushion next to him. 

He leans over you, sniffing the area around your shoulder. You stiffen. “You smell so good, better than all those flora bitches.” He growls. “I like your natural…musk.” Oh Gods did this man – who probably has a wife and children – just compliment how you smell when you’ve been working all day? “What do you like about me?” What a loaded question. 

You smile, one that shuts your eyes – if he saw the look in your eyes he’d be sure to know you were lying when you said, “I appreciate your generosity.” You bow your head and the man laughs heartily. 

His tongue darts out to coat his lips. “I can be more generous if you’d like?” He moves himself closer to you. “I was blessed with wealth, good looks, and a tool to make women scream.” Please let the tool be an ice pick so you can lobotomize yourself. “Whad’ya say, darling?” He coos, going in for what appears to be a kiss even though you hadn’t been given the time to answer him. 

You grimace away from his advance, shoving at his chest. The eerie playful tone in the room suddenly seems to vacuum out. The fog is still thick from the burning opium, but you don’t miss the way the man before you lunges for you. He’s panting above you with a charming pointy sneer. “Ah ah ah, not so fast. You haven’t serviced me, whore.” He digs his nails into your shoulder, pinning you to the wooden floor. “Look at you, begging for my cock with your eyes, ooohh you want it that bad you slut?” He hisses, fumbling with the buckle of his Western-style pants. You squirm wildly under his grasp but it’s like he’s infused with superhuman strength. “I’m gonna fuck you and then, as your reward,” His face is next to yours now, eyes glowing an electric yellow, pupils in slits. “I’m going to kill you.” His hand is on your throat, crushing your windpipe. You choke on what little air you were able to breathe earlier. 

A demon, this man was a demon. One of your kind. No… he wasn’t. He was something else. He was driven by the carnal desire to fuck and kill. You were too weak to push him off, your internal forces constantly warring against each other. You had always presented as human, meek, malleable, and obedient. What you would give to have your demon side come forth, bite this fucker’s head off. You want to scream – but on account of his claws sinking into the back of your neck – if you even moved that would surely be the end of your life. 

He tears your yukata to shreds, ripping the soft skin of your stomach open as well. Your mouth opens the pressure of a scream pushing against his hand. Blood mixes with the tattered cloth, the cotton dying red.

Muzan pauses, Daki grumbling about some inferior human drama. His eyes search the room, this time Daki taking notice from her self-indulged rant. Where was that smell coming from? He stands, silencing Daki before she can start whining again. The potent smell of blood was swirling to the top floor, but not just…any blood. “YN,” He hisses, the annoyance, rage, and blood-boiling sensations he felt earlier returning tenfold. Why were you bleeding? This was fresh cut blood, not from the dues women endured every month. He needed to find you, or he feared the worst. “I need to go.” He barely says to the demon next to him. Her face morphs into one of anger, and before she can hurl anything at him, Muzan slips out of her room. Where were you? He follows the pungent scent, clambering down the stairs and rushing down the hall until he’s in front of a private room. He’s sweating, for once fear is humming in his ear. He shoves the door to the side, witnessing a demon hunched over your body. 

Your blood is pooling around you dying the wonderfully blue yukata you wore earlier a sickly brown color. The demon doesn’t have time to look up because Muzan is already crushing its head, slashing its throat to shreds of what it once was. 

The room is covered in blood but the demon is dead. Muzan slides to the floor, cradling you in his lap. “YN, no, no please don’t die.” You were his miracle. You were his hope. If anything could save his damned soul it would be you. His arms are trembling as your stomach bleeds out, the skin marred, and…God the smell of your blood was driving him mad. It was something he shouldn’t be thinking about as you bleed out under him. You needed to regenerate. He wasn’t sure if you could so maybe your demon just needed a little push?

With his free hand, Muzan tears the flesh from his arm, bringing it down to your mouth. His blood trickles onto your lips, sliding into your mouth. After a few silent beats, your eyes shoot open. Muzan has never felt such joy as this very moment. Your arms wrap around his, bringing it into your mouth. Muzan hisses at the way your tongue dances around his wound, lapping up the blood he shed for you. You’re panting, gasping for more. Your eyes glow as you drag your tongue up the muscle of his forearm. His blood flows through you like your own life force, strengthening your nerves, hardening your muscles. He has made you stronger. 

It sends a pinch of desire through Muzan. He hadn’t felt the heat of wanting to sink his cock into the warmth of a cunt in decades. You were mouthing at his arm, wounds healed on both ends, but now that you were moving the once whole yukata falls off your shoulders. Blood trails from your lips down your chest, between your breasts. Muzan was never one to fend off his desire to want. He took whatever he wanted, without a care. He wanted to take you without a care. Fuck you senseless into the floorboards, claw at you, feed on your blood while you fed on his. It was ecstasy just imagining driving his cock into your pretty tight pussy. 

“I should’ve never left you.” He whispers and it sends a rolling wave of want through you. You move to straddle his lap. 

“Then don’t leave me now.” You could both smell it, the heat and arousal in the air. “Take me, my Lord.” He smirks, holding onto your thighs. 

He hums, enjoying the way you’re bare in front of him. You were a sight to behold. “Mmm, such a smart girl.” A portal opens underneath him, the wooden floor sinking into an expanse of rooms, platforms, doors, lights, and endless corridors. The sheer speed whips your hair around your face until – it doesn’t. You’ve stopped in the middle of whatever this place was. “Welcome home,” Muzan’s pink eyes darken to a deep crimson as he sits up straighter, pressing himself into you. You moan in delight as his hands work their way up your hips, sitting you down on the stiff part of his lap. 

You tilt your head, peeking at him. “I’ve never liked pants,” you mumble, playing with the hem of his. He chuckles his smirk growing. 

“And why is that?” He inquires, moving his tongue to lick up the blood that has traveled toward your navel. You choke out a moan as he makes his way between your breasts. You can feel his teeth against your skin and it’s a wretched thought. “Aheh,” He swipes at the crest of your breast. 

“H-hard to get off.” Muzan hums against your skin in agreement, but he’s too preoccupied with the way you tremble with untapped pleasure. 

He wants to tear into your flesh, mark you as his, burn only his name onto your tongue. “Such an eager kitten,” He licks his lips, capturing the back of your neck in his hands. “You want me bare that badly?” All you can manage is a small nod as he gingerly moves you so that you’re laying down. Your hips are still lined up with his as he gazes at you. “I can promise you I have a similar urgency.” He grins, pulling the belt from his breeches with a smooth movement. He tosses it to the side, but doesn’t make any more movements to pull his pants down. Muzan notices your heated gaze pointed toward his hardened groin. 

Did you know nothing about the workings between a man and woman? His eyes trail down your body, stopping at the apex of your thighs. He wraps his arms around the bend of your knee, smirking when your eyes widen in surprise. He tugs you upwards, to where your legs are over his shoulders. Being this close to your glistening pink cunt made his groin stiffen even more, if that was possible. The smell of you was intoxicating. He couldn’t help himself. “What a fucking view.” He growls. 

Muzan buries his head between your thighs, latching his mouth onto your swelling clit. You gasp in pleasure, breaths turning into ragged moans as he plunges his tongue deeper into you. “O-oh my God, f’ck, ngh.” With the way his tongue his twisting and sucking inside of you, breathing seemed impossible. His claws dig into your outer thigh, scratching red trails to your knees. He devours every bit of you he can reach, crazed by the tangy sweetness of your arousal. Your walls were squeezing around his tongue, heat running through your body. 

Your own hands find your stiff nipples, rolling them around in your fingers. You couldn’t get enough, it was the same feeling you received from drinking his blood. Heat rolling around in your veins as his eyes take in your puffy cunt and how your eyes roll to the back of your head. He maneuvers one hand from under your knee to the one place that was being ignored on you – your entrance. It was like the gate to a shrine and he wanted to worship there for eternity. “Look at how fucking wet your cunt is.” His pointed nails shape into shorter rounder ones, he dare not damage this holy place. Then, without warning, he presses two fingers into you. A yelp echoes across the void of the infinity castle. “Ahhh, shit,” You huff, tensing from the sensation of your pussy being stretched. 

Muzan knew you were a virgin, he would be lying if the fact didn’t make him grow more feral to have you sit on his cock and take his seed deep within you. He wanted you. He wanted you. He wanted you. That was all he could think about while lapping up your wetness. 

The slick from your cunt was sucking his fingers in, a growl rumbling around your clit. This makes you scream out as a shockwave shoots through you. Your thighs are shaking and every once and a while – as Muzan still selfishly fingers you through your climax, sucking on your clit – your body will twitch. Heavy and heady moans fall from your lips, breaking into whines as you come down from your high. 

“You did such a good job my sweet,” Muzan lowers you gently back to the floor. Your neck is sore from being at an awkward angle for so long, but you would give anything to see the disheveled man before you with your arousal still on his lips. “That’s it. Prefect. You’re so perfect.” He mutters, licking his lips and watching you still play with your nipples. 

Though you feel like you’ve just ascended, you crave more. You want Muzan to breed you like his own personal slut. “M-more,” You gasp. “I feel so empty my Lord.” You huff, the edges of your voice bleeding to a whine. Muzan’s eyes widen. He hadn’t intended to fuck you just yet. Give you some time to grow accustomed to sexual things so it wasn’t rushed, but your eyes are pleading him to continue. He’s… nervous, which isn’t like the demon king. He’s so eager to please you. Make sure you’re comfortable. He wants to give you hell, heaven, and the earth. 

“You’re practically begging me.” He chuckles, unsure if you really knew what you were asking. There was no way that once Muzan slid into your heady cunt that he would not ravish you. There was no way to tell time in the infinity castle, so there was no way for him to know when to stop until he was satisfied. You squirm to get closer to him, spreading your legs wide for him. His gaze drops from yours to your center, whatever shred of humanity that was left in him suddenly flying away. “Such a filthy slut. You’re already hungry for more? You want me to fill you up? Then beg for it.” His eyes narrow into slits, the magma growing in his belly. 

Your body cools with a shiver of excitement, as you reach down in between your thighs. You purse your lips and then spread your labia apart. The cool air tickles the sticky wetness but you can tell it’s doing something for him. “Please, my King, I want you to fuck me so hard I can’t think. I want you to take my virgin pussy and make it yours.” 

The corner of his mouth ticks up in a smirk. “As you wish my Queen.” He frees his cock and you have to take a moment to gulp at the sheer size of it. The head is leaking precum and bruised a red color from the lack of release. The shaft is a pale pink, a thick vein running down the underside. The muscles of his hips also catch your attention. They were unlike the drawings some of the courtesans had shown you. His were muscular, ready to thrust into you for hours. 

Muzan lines himself up at your entrance, this time with the head of his cock. The idea was thrilling, finally pushing into your pussy and breaking the barrier of your womanhood. He hisses as your slick coats him, making it easy enough to start entering you. Your face contorts with a mixture of pain and pleasure. “Shhh, you can take it.” You want to wiggle away from him, the pain of his member stretching you out is enough to break you. “Ah ah ah, you’re not going anywhere pretty girl. Remember you asked for this.” Muzan leans over you seizing your mouth with his own. You share a leisurely kiss as he swallows your moans. 

He feels the head of his cock hit your hymen and with a wince he thrusts past it. He can feel the rush of silky blood around his cock, but he tries his best to divert your attention with heated kisses. You break free, a long drawn out moan gasping out of you. “Ahhh, oh my, hngh nngh yes!” 

Muzan nuzzles into your neck, the feeling of your walls clenching around him driving him practically insane. “Yeah? Tell me how good I am. Tell me how good I am at fucking you.” He hisses out, desperate for your compliments and approval. 

“Nnnggh, s’good, f’ckin’ me s’good.” You slur, drunk on how he guided a new path into you. You pant and writhe under him, eyes fluttering shut. 

“Not yet my love, I want you to watch.” He starts to move his hips and you wince in burning pleasure. “That’s it. You’re doing so good.” He grunts, snapping his hips back into you. The wet slap of skin hitting skin sends shivers down your back. 

You’re straining against the build up in your stomach, a pit of coils wanting to spring forth. “Mmm, harder.” You huff, reach out to grab the back of his neck. He shakes his head, a playful smirk on his swollen lips. 

“Use your manners.” He teases, squeezing his eyes shut. 

“Please fuck me harder.” You mewl just as he starts to thrust into you with a quickened rhythm. Your breath is sucked away by the pure bliss aching from the friction. 

Muzan bites down on his lip, brushing a few curls that had come free from behind his ear. “You like it when I do that?” He quizzes, fucking you harder. You can only manage a nod.

Your voice has grown hoarse from moans breaking into screams and whines. You buck your hips along with his as you arch your back, tumbling over your peak. “F’ck, haa haa hnngh,” You squeeze his cock and release his neck, breathless from your second orgasm. 

“Cum all over my cock, fuck,” Muzan growls, the feeling of your slick cum coating his length. He was gliding into you with such ease. He would apologize to you later for this. He pounds into your sensitive cunt, overstimulating you as you cry out. He rams himself into you and stays deep within your pussy. Panting heavily Muzan finally crashes over his own wave of pleasure. Splurting his cum around the walls of your pussy. He doesn’t want to pull out – for one fact he wanted all of his cum to stay within you – and for another fact, you were all the salvation he needed. He could find redemption with you. He rolls you both onto your side, hiking your leg over his hip to make sure he can stay inside of you. 

This was it, you had driven him to the edge and he would make sure to never let anything else touch you. As he gazes upon your soft features drifting off to a satisfied slumber he feels what once was his heart ache. “We should get married.” He blurts out.