First Butterfly Brother (Oneshot) || Demon Slayer AU Fanfic

First Butterfly Brother

Genya was sitting outside Butterfly Mansion, he was still silently thinking about the incident with his older brother Sanemi Shinazugawa, the Wind Hashira and his great friend Tanjiro Kamado. Even though Tanjiro tried to help the Shinazugawa brother's relationship. In the end, it didn't work and Sanemi still didn't think Genya as his little brother now. Genya was thinking deep in his thoughts until he heard a female voice.

"Mr. Genya?" It was Aoi.

Genya blushed a bit when he saw Aoi in front of him.

"Oh, hey Aoi," he greeted, shyly. "What's up?"

Aoi thought for a second about what Shinobu said to say to Genya before speaking, "Do you mind coming with me for a second? It's important."

Genya nodded. "Sure..."

"Alright," Aoi gets up before turning her back to Genya who was still in deep thoughts thinking about the incident. "You coming?"

Genya's head shot back up as he went back to reality. "Mhm."

"You better hurry up then, remember, it's important." Aoi reminded.

Genya followed Aoi inside the Butterfly Mansion to only see Shinobu, Kanao and the little butterfly triplets (I know Naho, Kiyo and Sumi aren't biologically related as triplets but it's way easier to call them the little butterfly triplets.)

"Oh my, Genya, you're here." Said Shinobu. "Come take a seat."

Genya blushed in embarrassment before walking to an empty seat to sit down on it. He looked at Shinobu nervously not knowing what's she's going to say. Aoi walks next to Kanao standing still.

"Genya, I know about the incident between you and Shinazugawa." Shinobu responds. "It was painful, right?"

Genya eyes opened in shock that Shinobu knew about the incident. "Yeah... I tried to talk with Nemi but-"

Shinobu places a hand on his shoulder. "I was aware about this a little while back when I talked to Shinazugawa once." She explained. "He said he didn't have a brother and thought I was just hallucinating."

"That's true..." Genya responds in a sad tone. "Nemi and I used to be so close back then, but now, he doesn't see me as anything."

Shinobu looks down upset as her smile faded away like dust, she wished Genya and Sanemi would still have a good sibling relationship like with her and Kanae.

"You know Genya, if you want... you can become the first butterfly brother in the Butterfly Mansion." Shinobu smiled.

"I- me? Are you sure?" Genya questioned, not expecting that.

Shinobu shows Genya a butterfly clip similar to hers but with a different colour.

"The choice is yours Genya," Shinobu replied. "If you need to feel like you have a family. We're here for you..."

Genya was staring at the butterfly clip. Becoming the first butterfly brother would be really nice but that means he'll have to leave Sanemi behind, but also, their relationship wasn't going very well so it would be nice. Genya hesitatingly takes the butterfly clip before putting on the back of his hair.

"I accept your request." Genya smiled, softly.

The little butterfly triplets cheered in happiness for Genya's decision.

"Congratulations Genya!" The little butterfly triplets cheered all together at the same time.

The start of the Butterfly Brother, has begun today.

A couple days later during Tanjiro's training at Gyomei's course. Genya explains everything about him becoming the very first butterfly brother to tanjiro in great detail describing everything.

"Wooahhh," Tanjiro's open happy mouth widened as he made that comment. "It must be great being a butterfly brother isn't it, Genya?"

Genya chuckled at Tanjiro's comment. "Haha, it sure is."

"Now I wish Nezuko and I could be apart of the Butterfly Family or is it now Butterfly Siblings because it would no longer be Butterfly Sisters because you're there now Genya and you're a male!"

"Hah! Possibly," Genya laughed changing his sitting position. "I like the butterfly pin Shinobu chose for me as well."

"Right! I mean, purple and light black does suit you!" Tanjiro commented pointing out the colours.

Tanjiro and Genya were happily laughing as Gyomei watched from afar behind the trees.

A little Timeskip.

Sanemi heard about Genya becoming the first butterfly brother by some lower rank demon slayer's gossips which made him slightly irritated about that. He was Genya walking one night and decided to go up to him.

"Genya."

Genya immediately turns his head to Sanemi voice as he walked up to him.

"Yes. It's what it looks like-" Genya got cut off by Sanemi.

"So you're saying you became the Butterfly brother, without your older brother's permission?" Sanemi responded.

Genya then took a deep breath before saying, "I know, our brother relationship didn't go well anyway, so I'm moving on from you. You don't even see me as your little brother anymore, what kind of garbage is that? All I wanted to do was apologise for everything." Genya takes a step forward before stopping and saying his final words to Sanemi.

"I'm really sorry, Sanemi." Genya apologised as he walks away.

Sanemi felt like his heart has cracked. The fact that Genya didn't call him "Nemi" and just by "Sanemi" felt painful.

Sanemi softly mutters to himself. "I'm really sorry too, Genya. For being a bad older brother to you, I hope you're more happy with being a Butterfly brother." He felt like he was going to cry a little but immediately wiped his tears before heading off so no one could see.

Later, Sanemi saw Obanai with his snake Kaburamaru sitting and patiently waiting for Sanemi on the small staircases. Sanemi sat down with them acting fine like nothing happened.

Obanai turns his head to Sanemi.

"Hello Shinazugawa," Obanai greeted. "What took you so long?"

"Nothing, just had to deal with some weak lower rank demon slayers." Sanemi lied trying to act like his usual self.

"I see," Obanai replied. "Have you heard about the news?"

"News?" Sanemi repeated.

"About..." Obanai thought if he should tell Sanemi about Genya being a butterfly brother but thought Sanemi wouldn't care. "Never mind."

"I know what you're going to tell me," Sanemi replies. "About... Genya being a butterfly brother."

Obanai nodded truthfully.

"Correct, I thought you wouldn't care so that's why I decided not to tell."

Sanemi sighed.

"Truth is... I do care about Genya, it's just... I don't know but do not mention that ever again to me, I'm not in the mood."

Obanai nodded in respect.

"Alright."

Hey!! You made it to the end, hooray! :D
I had a blast making this fanfic and just adored the idea.

Cast:
Genya Shinazugawa
Aoi Kanzaki
Shinobu Kocho
The Little Butterfly Triplets (Naho Takada, Sumi Nakahara and Kiyo Terauchi)
Kanao Tsuyuri (cameo)
Tanjiro Kamado
Nezuko Kamado (mention only)
Gyomei Himejima (cameo)
Sanemi Shinazugawa
Obanai Iguro
Kaburamaru

Thanks for reading and enjoy your day! Hopefully you enjoyed it enough that you even out this in one of your readings list, favourited it or both. (That would be very nice you know? :D)