The Unknown Hashira (Demon Slayer x Reader)

[17: Past Centuries]

WARNING!!

This chapter will contain major spoilers from the manga and it will involve Muzan's background. So if you haven't read the manga then read at your own risk!!

ʚɞ ʚɞ ʚɞ ʚɞ

ʚɞ ʚɞ Flashback (500+ years ago) ʚɞ ʚɞ

In the Heian era, a woman gave birth to twins, one of them alive as a newborn while the other one is dead. Having many heart complications in his mother's womb and being deemed as a stillborn, having no breath and no pulse. Only got recognized to be alive when he was almost cremated, screaming his protest. 

This child's name is Muzan Kibutsuji. Throughout Muzan's life, he's suffered so many illnesses giving him such phobia, like thanatophobia. He's very weak to the point that he can't even get out of his futon or else he will suffer. The only thing that he could do is look outside and see his twin get praised by his mother. 

His twin is very different than him, always living life as a normal energetic kid, never having problems with any sickness. He has never remembered his twin even whining that they're sick, he can just hear them screaming at their mother that the food is good. Those are the only things that he's heard from his twin. 

He's hated his twin ever since he had consciousness. He hated how his twin always gets the limelight, always getting praised for doing the simplest of things, even getting called the 'miracle child.' He hated that. 

One day, Muzan, got a certain disease that would kill him before he reached the age of 20. This news was spread all over their household and it reached his twin Y/n, ever since they received that news they started taking care of Muzan. 

The man is annoyed by this, always needing to communicate or at least socialize with his nemesis. Even if he always screams at Y/n and abuses them and does not care for their kindness, they didn't give up, they kept on taking care of Muzan. 

After a while, Muzan's doctor gave him a special prototype medicine, but it appeared to have failed. Enraged by his worsening condition, Muzan killed the doctor, then he realized that the medicine did work. He realized that he needed to consume some human flesh, craving them, but he wasn't bothered by this fact, always hated humans when he was born. But he also realized one thing...

He can't go under the sun, his body burning severely. That's where he regretted killing the doctor before he could have finished the "Blue Spider Lily" treatment. He was annoyed by this not liking this much change in just a couple of days, so when his twin came into his room, he did one thing he's always wanted...

Attack them!!

"Onii-san, here is your foo-" Y/n immediately was thrown on the tatami mat making them groan, they looked up and saw their twin standing and smirking down at them. "Oh, onii-san, you're okay now! Did the medicine work?" Y/n asked giddily, happy about their brother, not knowing that this just enraged the man even more. 

"This is why I've always hated you, you're always nice to everyone, I hate that," Muzan said as he grabbed his sibling's collar, he threw them on the tatami mat, much harsher this time. "Since you're my twin, you should suffer the same as I am, right? Let's see if the people around you will still love the miracle child!"