Mostly Giyu Chapters Because I love Him

If Giyu and Aoi were siblings, and Giyu turns into a demon.

Aoi: Sister Shinobu! Sister Shinobu!

Shinobu: Yes Aoi?

Aoi: Where's water pillar sama?

Shinobu: Tomioka-San is in the garden, why are you asking?

Aoi: I want to talk to him about something

Shinobu: He won't talk

Aoi: Still

Shinobu: Go ahead then

Aoi walked to the garden to see her brother. Though, no one knows their siblings. "Onii-chan!" She yelled, "Can I come with you on your mission?"

"Aoi, I don't want you to get hurt. It's a hashira mission"

"But- I want to come with you!" She said

"Fine, You don't have a katana though"

"Yes I do! I just never used it, I just sharpened it over time" She added

"Go get it, it's in 2 hours"

"Ok!"

Aoi went to get her sword, she saw Shinobu on the way. "Aoi? Why do you need your katana? You don't go on missions?"

"I asked water pillar sama if I can go with him! It took a bit of time but he agreed!" She yelled

"That is a hashira rank mission, your a Mizunoto"

"I want to help him though, he still hadn't fully healed so maybe even I can help him. We know the same breathing technique" Aoi explained, she sees Shinobu realize something.

"You have a point, he better protect you ok?"

On Giyu's and Aoi's mission

"Uppermoon 3 and 1.. Aoi run!" Giyu yelled as he pulled out his katana and jumped in front of Aoi to protect her.

"What is she to you hashira?"

"I don't want to kill the girl" Akaza pointed out the obvious fact to Kokushibo.

"My little sister, AOI RUN! I TOLD YOU!"

"I don't want to leave you here like this!" Aoi protested, but Giyu had already thrown her out the room. She immediately went to get mor hashiras as fast as possible, to help her brother.

When she got there

There was a hashira meeting in the process, Aoi came running in crying. Sobbing, she yelled out 'please help him'. They all turned to her. "Him?" Shinobu asked.

"G-G-Giyu san...He- he's fighting uppermoon 3 and 1! Help him!"

They all followed her, they said farewell to the master and followed Aoi. Shinobu carried her on her back so they would get there faster. Aoi navigated them to Giyu.

After a long time, they arrived. They thought Giyu already died and got eaten, but he was there... barely standing followed with a exhausted sigh. Akaza was still alive and shoved his fist in Giyu's mouth so he would turn into a demon.

Giyu then fell, the place was a wreck. They rushed to their water hashira to help him. Aoi was wailing and sobbing, Giyu was gasping for air and he was barely even breathing.

Two long white horns started to grow o his head, with black and gold outlining it. A blue oceanic mark on his face, his face contorts in pain. He wakes up and notices he's hungry...Why? He thought.

He immediately backed away, he put one hand on one side of his head and the other hand on the other side. He was clutching his hair, trying his best to restrain himself from attacking his fellow hashiras.

The newly made demon hashira passed out after healing his wounds and from using up too much energy.

In a meeting about Giyu, like the trial Nezuko and Tanjiro had.

"He's so cute!!" Mitsuri yelled out, pointing to Giyu who was sleeping in Aoi's arms.

"He killed 2 uppermoons, uppermoon 1 and 3." Sanemi explained

"We were all there!" The loud owl- I mean Rengoku screamed.

"It's really impressive, defeating 2 uppermoons and still be standing after that? He most certainly has my respect"
Iguro never thought he would say that.

"That's so nice of you Iguro san!!" Mitsuri sat next to Obanai, complimenting him on his new kindness towards Giyu.

"Thank you, Mitsuri...." Obanai blushed, Kaburamaru bit him because Kaburamaru never likes it when that happens.

Giyu started to wake up, Aoi looked down at her brother who had shrunk adoringly. Giyu woke up from his sleep and looked around, he then saw Aoi and smiled. He griped the white dress she has over her uniform.

"Aoi, Aoi, Aoi" he said as he looked up at her

"Hm?" She said

"Am I a demon...?"

"Yes, yes you are. But you're a good one! Just like Nezuko."

"Just because you have a relation with each other dosen't mean the other won't betray you!" Sanemi yelled, obviously it was That eyebrowless Chihuahua.  He does have a point though.

Words: 794
(Including this)
I never see Aoi and Giyu sibling AU so I wanted to make one. I really like this too so Maybe there will be a part 2