REQUESTED BY: Official_Ankha

A/N: The reason this isn't titled "Muzan's Sister" is because for Muzan's path, you're Yoriichi's sister - and that quite obviously changes things (I wouldn't write incest here, that's pretty nasty).

Enjoy!

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Growing up the sister of the most powerful man in Japan was an unbelievable experience.

From the moment he was born your younger brother, Muzan was a sickly thing requiring more care than your parents were sometimes able. At the tender age of five you learnt to care for your new baby brother, filling in where your parents - especially your mother - could not. You both grew up close, with him regarding you as more a mother than your own.

When the time came for you to be married off, however, he flew into a rage. You were already twenty-four, far past your prime as a young woman, and your parents felt that Muzan didn't require as much care as you had been giving him for the past twenty-odd years.

In the days before you were to be married, something strange happened.

Muzan had been getting treatments from a famed doctor, but the doctor had been recently killed - and your brother had made a full recovery. Even worse yet, it seemed he couldn't go out in the sun, something that enraged him. You had always longed to take him out in the sunlight to play once he got better, yet now he was forced to spend his days inside despite no longer on death's doorstep.

He stole you away from your fiancé in the dead of night, somehow convincing you to run away with him. Your love for your brother overrode your love for your parents and the duty to your husband-to-be's family - and you escaped with him into the mountains, where he finally revealed what he was.

Despite being horrified, you were convinced you could find a way to save him - and you spent fruitless years searching for the plant he desired. He never got angry with you, or at least not in the way you witnessed him angry with his subordinates - though he was emotionally cruel when he felt you were lacking.

Finally, after almost ten years of searching, you collapsed in an illness. Muzan was at your bedside, offering you another chance of life - and you took it, wanting nothing more than to be at your baby brother's side.

The process was painful, yet you came through and triumphed over certain death - consequently, however, you could never feel sunlight again.

It was all worth it to see your beloved little brother smile like he had when you were both human... wasn't it?

Tanjiro:

You had known nothing about this enigmatic boy, only that your brother hated him with every fiber of his being. You had witnessed enough rages from him to learn that Kamado Tanjiro was a name not to be uttered, lest you wanted a swift punishment - one of his more unfortunate subordinates was a prime example of this. (It had taken you hours to get all of the blood out of your kimono.)

Nezuko:

You smell like him. That's the first thought that crosses her mind when you both lock eyes for the first time. Instead of malice, however, she senses a deep sorrow - and you look at her with such gentle eyes that it's hard to see you as an enemy. If it came down to it, she would have few doubts about killing you - but a mutual understanding crosses between you when you see the way she protects her older brother - and she refuses to fight you if you were ever alone.

Zenitsu:

The very first time he actually saw you, he was scared to death by the man standing beside you, so much that it took him a minute to realize who he was looking at. You were so beautiful, regal, and if the king of demons wasn't standing there and staring at his group with enough malice to kill them twelve times over, he'd probably try to talk to you.

Inosuke:

A demon's a demon - that's what he thinks, and he would've beheaded you on the spot had he realized what you were when you steered him away from Douma's domain.

The hotheaded boy struggled against your hand, yelling and trying to get you to let go - but your determined gaze and firm grip were too much to break free of. As soon as he was far enough away, you let go - and you sternly told him to stay away from the Upper Kizuki, as you didn't want to see him die.

He wondered about you, thinking about you from time to time until you met again - this time at the right hand of Muzan. That's when he realizes what you are, and that's when you give him a faint smile and a wave. He realizes he has to kill you, but he doesn't quite want to do it.

Giyuu:

The sister of the most feared man in Japan - a tantalizing target, most would say. But when he stumbles upon you in one of your rare outings from the Infinity Fortress, he has a hard time reaching for his sword. You're minding your own business, taking in the sights and sounds of the town with such childlike wonder that he wonders if he's even seeing the right person. And then you lock eyes - and he's struck with how... innocent you look. That's not the face of an unrepentant killer. He hesitates for just a little longer, remembering how Nezuko looks at him with that same face - and you disappear into the crowd, looking for something else to experience before your brother comes back to get you.

Kyojuro:

He's heard rumors, rumors of Muzan's ultimate weakness, and it's not the sun. Rather, it's a woman. He has to say he's skeptical about it, but when he finds you in the middle of nowhere, being escorted by Upper Kizuki 1 himself, his first thought is that he's completely out of his depth and he needs to call for backup.

Despite Kokushibo getting in front of you protectively, you peek around him, fascinated by the Flame Hashira's appearance. Such a gentle-looking man was this powerful? If you weren't with your brother's most trusted minion, you'd have asked to see him in action. (You really don't want someone to die right now - Muzan would be upset that the Corps would be on even higher alert.)

Muichiro:

You feel a sort of fondness towards him when you see him for the first time - you've heard of the Mist Hashira, and you feel for him. He reminds you of Muzan, sometimes; when you were both children, and when you were the person he loved most in the world. You hesitate to kill him, and you hesitate to call for help when you're alone together for the first time.

The boy is curious, and a little shocked, when you merely sit down and don't move. You regard him with a soft gaze, pained and a little nostalgic, and he can hardly help from asking why you're looking at him like that.

Shinobu:

It doesn't matter who you are or what you think, she reminds herself as she comes face-to-face with the very woman the Corps has been looking for. She's caught you halfway through a stack of books in your private rooms, looking up at her in surprise - and then fear. You don't look like the sister of a killer, and you certainly don't look like the demons she hates so much. But looks can be deceiving, and she knows that all too well.

"What are you doing here?" You whisper frantically, scrambling to your feet. "If-- if he catches you here-- you need to go!"

Why are you trying to protect her? She's come to kill you - and her grip on her sword, tipped with poison, clenches as you push her by the shoulders back towards the door. Hell, you look like you would let her - so why is she hesitating?!

Gyomei:

You've heard about this man. The strongest in the Corps, and a real threat to your brother's forces, you've heard many rants about Gyomei and you hardly know what to think when you actually see him in person for the first time.

You'd come to a remote village for a festival, shadowed by Kokushibo. You noticed the Stone Hashira walking with a little girl, talking softly with her until she found her parents. You noticed the smile on his face, pained, but relieved, as the crying girl raced into her father's arms. And you noticed the way he carried himself, so full of pain but so full of hope. He turned his head, and if he had sight, you'd have locked eyes - and his expression wavered for a moment before he bowed his head to you and walked away.

Gyomei was a mountain of a man, but you felt a certain kinship with him. You watched him go, hoping he never had to face any of your brother's Kizuki.

Sanemi:

He's ready to kill Muzan in whatever way he can - but when he catches rumors about you, rumors that you were Muzan's most prized secret, he figures he can switch targets.

He can't help the grin when he finds you in the fortress, brush in hand, painting scenery. You remain as calm as you can, though he can see the panic in your eyes as he unsheathes his sword.

To his utter surprise, you set the brush down. You give him a painful smile, and you ask him if he has family.

"No," he lies, and you nod in understanding. Genya's face flashes through his brain when you look up at him.

"Please... forgive me for indulging my little brother's wrath for so long," you murmur, and in the same instant, he feels the floor give way beneath him and he's dropped into another area of the building.

Akaza:

As well-kept a secret as you were, your brother couldn't be at your side all the time. When he wanted to go out of the fortress, he usually sent you with Kokushibo - but this time, he showed you someone new.

"This is Akaza, my third," he introduced, pointing out the kneeling man with pink hair. "He will watch over you until I can return." He turned his fierce gaze on the man, nearly hissing, "Do not cause her trouble. I trust that you can manage that."

"Yes, my lord," he uttered.

The second your brother was gone, he dared look up at you. His eyes widened minutely, but he averted his gaze.

He was quiet, solemn, but he was a good guard. He walked with you, listened to you talk - and he didn't seem to mind when you took him by the hand and excitedly pulled him towards your favorite place, an indoor garden that you personally planted. His cheeks flushed a faint dusky color when you looked into his face so earnestly, starved for good company.

As fond as he became of you, he never spoke a word about it - and certainly not to Muzan. And as fond as you became of him, you made sure to keep it close to your heart - the last thing you wanted was for him to be punished because of your feelings.

Douma:

He scared you, the first time you met.

It was completely on accident, as he came across you in your brother's office while he was working. His stare was just a little too intense, a little too interested, and Muzan teleporting you away made you sigh in relief. You'd heard tidbits of him from Kokushibo, when he guarded you - and you didn't like what you heard. It seems your brother still didn't trust him around you, and you weren't going to complain. Sometimes he cheerfully asks about you, asking why you never showed your face. You were so beautiful and so mysterious, he longed to meet you face-to-face and see just why his lord was so determined to keep you hidden away.

Kokushibo:

You were Muzan's best-kept secret, even from most of his subordinates.

That didn't stop Kokushibo from finding out about your existence, and completely by accident.

Muzan, thankfully, was merciful - and instead of slaying him right then and there for stumbling across your apartments in the fortress, he introduced him to you, his older sister - and Kokushibo was entranced by your beauty. Your hesitant, yet polite smile and the way you regarded Muzan stuck with him, even as he went about his regular duties. Muzan swore him to secrecy, and in turn, he was allowed to protect you when you walked the streets (if your brother ever let you, anyway).

It was awkward between you and Upper Kizuki 1 for a long time. You hadn't been around another man in centuries, let alone Muzan's most trusted subordinate - and he was so focused on his duties that he paid little mind to much else but guarding you when he was near.

Soon enough, however, you began to feel an interest spark towards the stone-faced man. Though he had been changed drastically since shedding humanity, he was still beautiful - long soft hair kept in a pony, those piercing eyes that seemed to see right through you, the soft way he spoke - Kokushibo was graceful and skilled, and you soon found yourself excited to see him.

Muzan knew of your affinity for Kokushibo - he must have been reading your thoughts and memories again - yet he said little in regard to his Kizuki. Even when he prodded you for answers, he remained aloof. You were still his prized sister, and he wasn't about to just let you have another man steal your affections.

For now, you remain pining from afar, unsure if the man will ever return your feelings, and afraid of what your brother will do if he should return them.

Muzan:

Growing up the sister of the most powerful man alive was certainly an experience.

Being the older sibling to your twin brothers, you were expected to be married off as soon as you were of age. Once you matured, you could hardly spend enough time with either Michikatsu or Yoriichi - not that you would have spent a lot of time with the younger brother anyway, given how strict your father was about keeping him separate from the two of you. Things only grew worse when, after your mother died, he left home - leaving you devastated and Michi uncharacteristically cold.

You were quite close to Michi, and the day you were to be married off, you could hardly keep your tears concealed when you bid him goodbye.

Several years went by, and you were content in your marriage - your father had chosen well, and your husband was pleasant to you. Your children were growing like weeds; it seemed like yesterday that they'd been but newborns. Michi had also gotten married, it seemed - and he brought his new wife by to introduce you. You'd missed your brother, and his wife seemed to click with you almost immediately. Life was good.

And then, one day, your world became cold.

You had been off visiting your sister-in-law when a maid from your house came screaming up the path, regaling a horrid story of how your husband and four children had been slaughtered, leaving you the only survivor. You'd been so upset you vomited.

And now, here you were at the ruins of what was a happy home. Your heart felt like ice in your chest as you came across your family's bodies.

You had not expected to become a widow at the age of thirty. You also hadn't expected to come across the man that slaughtered your husband in the same year.

Kibutsuji Muzan was an enigma. Charming at a glance, he quickly swayed your heart and left you breathless. It was when you turned thirty-one, when you reunited with your long-lost baby brother Yoriichi, that you finally saw him for what he was: a ruthless, narcissistic killer. Yoriichi managed to beat him back and the two of you remained together until your sister-in-law offered you a home, far away from the painful memories of your life before.

Muzan remained intrigued in you, if not just because you were the older sister of his mortal enemy. He continued to stalk you through your life, always two steps behind. When you remarried, he killed your new husband. When you had children, he considered killing them too - but eventually he let them live, wanting to see what they would grow up to become.

You always lived on the edge of paranoia, until you finally turned thirty-five - and he visited you again.

You screamed and fought as he turned you into a monster like him - and when all was said and done, you were forced to become subservient to the man you hated most in the world. The next time you met your brother, he cried tears of anguish when you locked eyes - though you silently begged him to kill you, he refused to even touch you.

Your anguish only increased when you met his newest Kizuki, a familiar-looking man with a Slayer's sword - Michikatsu had become a demon, and had lost all memory of who you were. Your beloved little brother regarded you coolly, no warmth or love in his gaze like before. It killed you inside when he spoke of killing Yoriichi. What had happened between them? Why had your Michi fallen?

By the time one of his other servants, a lovely woman named Tamayo, escaped, she took you with her - and the two of you live in hiding together, far away from your nightmare and working tirelessly to kill him.

Though your old life is long gone, you still cling to the embers of what was, and you vow in your brothers' stead that you will kill the demon that is Kibutsuji Muzan. The simmering hatred in your heart fuels every day that you face.

You sigh deeply, shaking your head as you turn another page of your book. You have nothing but time; deep down, you wonder if the demon lord knows it too.

Yoriichi:

The moment you both first locked eyes, he felt something different about you. Something more solemn and subdued.

Then Muzan had stepped in front of you, baring his teeth in a menacing grin, and he knew.

The demoness before him was precious to the king of all of these hellish creatures... but how? Why?

He hardly paid you a glance as he fought Muzan -- and when he was about to deal a fatal blow, you cried out and covered the man with your body, desperate eyes searching Yoriichi's for even a shred of mercy.

"Please," you begged. "Please spare him."

Yoriichi hesitated.

In the next instant, Muzan was able to escape - but he was never able to forget the sight of such a pretty young woman pleading the life of the progenitor of demons. He never saw you again, but you had made such an impression on him that he held Muzan in a new light: the man, in some capacity, was still human - and now he had a weakness that could be exploited.

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A/N: I'm fighting for my mf life out here trying to research the Heian and Sengoku time periods >:(

The funniest thing about Muzan's sibling section is that he automatically ensured his demise when he turned her... no spoilers to anime-onlys, but I just found it incredibly hilarious to write.

Please tell me what you thought!