Muzan x sister reader

History

A/n
You guys wont probably get this chap🌝

In the Kibutsuji household. There were three children that was born. The two oldest were sick while the youngest was healthy and well.

As much as the parents loved it, they cannot choose the youngest as the heir as she was a girl.

All was live and and well until one day, the youngest one suddenly got sick.

They didn't know that even when she was healthy and well, she had very low immunity against illnesses, hence, she got hold of a disease which led her to her death.

No one knew what killed her, so at her death bed, she blamed her older sister whom she played with the most.

The fact that her older sister expressed sighs of jealousy of her healthy state was enough proof for her. Saying that her older sister cursed her to experience the pain and suffering her older siblings experienced.

The mother, filled with rage and sympathy for her youngest daughter's saddened heart wanted for her other daughter to experience the sadness the youngest felt.

Hence, she removed the heart of the youngest daughter's heart and made doctors of highest of positions to attach it to the oldest daughter. You could hear the pained screams of the girl around their estate. The pleads and begs for help were muffled as she was then gagged by the doctors.

The heart, attached to her right chest was now enveloped by the girl's body. As if it was her own.

And now, it beats like it was her own.

——

Days after the heart was attached, she almost died due to blood loss. It was considered as a miracle that she still survived through the ordeal.

After the heart became one with her flesh, she received countless nightmares. Making her scream every night I'm fear. She always avoided her sleep, that even her older brother got worried as she had the darkest eyebags he's ever seen.

She was even paler than him due to the lack of sleep.

It didn't end there though. She already avoided sleep, now she also needed to avoid being awake. Movement and sounds that weren't even heard by the others could be heard by her. Saying that she could hear the giggles of a child.

Her mind found the ordeal of the surgery so traumatic that it made it locked deep inside her head. She couldn't even remember why she had a scar on her right chest.

——

Once the eldest daughter became a demon. The hallucinations got worse. Words of hate could always be heard in her head. Laughter and blames was thrown at her.

A girl she she doesn't know would always pop up in the mirror, smiling and smirking at her.

But it all got worse whenever the eldest brother would send her out on a mission. It was as if she's asleep yet she know what goes outside. Speaking to her brother and victims with words she doesn't even use. She doesn't know what was going on.

But then, suddenly.

She saw herself stuck in a abyss. Infront of her was the light that showed the outside. No matter what she did, she couldn't get out. Atleast, that's what she believed.