•Our Bond• Yandere Rui X Child Sister Reader (Kimetsu No Yaiba)

Chapter 1

I love Rui very much!!! His backstory and dead was very sad.

I also immediately recognized his voice as Shigaraki's from Boku No Hero Academia since they have the same Voice Actor.

I saw some Rui X Reader stories, but I don't think there were any Rui X Child Reader stories or Rui X Blood Related Sister stories—or I just didn't see them.

I love to write 'Yandere Brother X Child Sister Reader' (Platonic love of course) and Rui is the perfect character for this.

By the way, the picture in the cover is not mine and is from Pinterest.

(y/n)= your name
Last Name: 'Ayaki'
Race: Demon
(Formerly Human)
Physical age: 5 years old
Biological age: Unknown
...

Flashback:

"Rui-nii!" You called your elder brother. You saw him watching other children playing in the snow. He himself of course couldn't join them due his fragile body.

"You should rest, Rui-nii." You said after you ran up to him. Rui smiled at you. "I'm fine, (y/n)." He reassured you. He tried to take a step, but suddenly fell face-first on the snow. You squeled in surprise. "Rui-nii! A-Are you okay?!" You panicked.

"It didn't hurt." Rui said. He turned around, laying on his back. "Mhm, I'm fine." He murmered, staring at the blue sky. You sighed in relief. "Rui-nii?" You called. He hummed in response, letting you know he is listening. "Mom, dad and I will make sure you get better and then we will play tag!" You beamed.

"Thank you." Rui said, glancing at you. "You always support me." He added.

"Of course! I love you!" You grinned. Rui's lips curved into a happy smile.

"I love you too, (y/n). I love you more than you can imagine." Rui responded.

—

You sat by Rui's bed, happily ranting about things until you saw Rui staring at something behind you.

You turned around. "W—...Who are you?" You glared at the man. "'Kibutsuji Muzan'. Don't worry, I'm here to help your brother." The male responded.

Muzan hadn't only turned Rui into a demon, he had also turned you into one—upon Rui's request.

"This way we will be like each other." —is what Rui said.

Everything went well until Rui killed a human for himself and you to feast on. You looked terrified at the corpse.

"Eat up, (y/n)." Rui said. He sounded cold, unlike usual. "N-No, Rui-nii. I can't do that." You looked up at him, refusing to eat the human despite feeling to urge to eat the human corpse.

Rui was about to respond until the door opened. Your parents stood there. "What have you done?! Rui!" Your father shouted. Your mother was only sobbing and quickly averted her eyes from the corpse.

"D-Dad! We had to eat! It's not Rui-nii's fault." You tried to defend your brother, standing infront of him now with your back facing him. Rui stared at you. "(y/n)..." He muttered.

—

"Can you stay here tonight?" Rui asked. You stopped in your tracks as you were about to leave his bedroom. You turned around. "Oh, okay. Why?" You replied, making your way over to him. "I felt a bit lonely last night." Rui whispered.

"I will be always with you! Rui-nii!" You reassured. "Thank you." Rui whispered.

You and your elder brother fell asleep together while hugging each other.

The sound of the door creaking open made you frown in your sleep.

Flashback end

You shook your head, preventing yourself from remembering your parents' dead. Sometimes you hate you remember everything so well.

' "It was your parents' fault for not accepting you both as demons. You were still his precious children, right?—So why did they attempt to kill you? They couldn't be your real biological parents, could they? They were fakes." Muzan said. '
Muzan's words from back then lingered in your head.

'You're wrong, Muzan. Mom and dad truly loved me and Rui-nii.' You thought.

"What are you thinking about?"

You turned around, facing Rui. He had changed, not only in appearance.

"Nothing, Rui-nii." You faked a smile at him. You don't know how to feel towards Rui. 'Rui-nii regrets killing mom and dad, but that doesn't bring them back from dead. Rui-nii protected me too from being killed...but I wish we all had just died together...'  You thought.