Multifandom Oneshots (RBB, Demon Slayer, etc)

- STILL BREATHING - (Demon Slayer AU)

TW: Un-cannon character personalities (in this AU, Kokushibo cares about his brother more than in the actual Demon Slayer storyline)

Fun fact: this oneshot/AU was based on a dream I had :)

So basically, this is about Yoriichi and Kokushibo. There WILL be manga spoilers in here, but only for Yoriichi and Kokushibo/Michikatsu's (I think that's how you spell it, correct me if I'm wrong) backstory.

The story starts when old, 80 (I think?) year-old Yoriichi tries to kill Kokushibo using the Sun Breathing technique.

Anyways, let's start! :D
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Third Person POV - Kokushibo
Kokushibo slowly turned around, shocked. His own brother had almost just killed him. He saw Yoriichi standing there, his katana in-hand. His now-white hair blew in the wind, unfamiliar to the dark red hair Kokushibo was used to seeing on his brother.

Suddenly, just as Kokushibo thought Yoriichi would try to kill him again—and this time, possibly succeed—Yoriichi collapsed to the ground, his body too overwhelmed from attempting to use such powerful breathing techniques. Kokushibo's brother was experiencing a heart attack.

Kokushibo just stood there, still in shock. He had almost died—and he would've, too, if Yoriichi had still been young enough to successfully use the Sun Breathing technique without earning himself a heart attack.

Kokushibo blinked and shook his head, his shock temporarily fading. Yes, he was jealous of his brother, but he just couldn't bring himself to kill Yoriichi, or watch him die. Kokushibo rushed to Yoriichi's side. Yoriichi wasn't breathing.

Kokushibo hesitated, then sliced his own arm. Why, you may ask? Because...in order to save his brother, Kokushibo knew he would have to turn Yoriichi into a demon. He wouldn't like it, but it'd be a win-win, wouldn't it? Yoriichi would survive, and he'd become more powerful. This thought came to Kokushibo's mind more bitterly than he expected.

Kokushibo gave Yoriichi some of his blood, which was connected to Muzan. To say the least, Muzan was very, very pleased with Kokushibo's decision.

Third Person POV - Muzan
As Muzan got the request from Kokushibo to turn a familiar person into a demon, excitement filled him. It was the human who had almost killed him so many years ago. Muzan could tell from the earrings the person was wearing.

Muzan began thinking about how powerful he would be if Yoriichi became a demon directly under him—under his control. Muzan would get so much closer to achieving his goal, too, with two extremely powerful demon brothers serving under his reign.

Muzan immediately accepted Kokushibo's request, smiling.

Third Person POV - Yoriichi
Yoriichi woke up laying on the ground. Hold on a minute, woke up? That wasn't supposed to happen. Yoriichi was supposed to be dead from the heart attack he could've sworn he'd just had.

His eyes narrowed. He was in the shade, so he didn't have the bright glare of the sun in his eyes, luckily. Someone must've moved him to a different location.

Two possibilities crossed Yoriichi's mind. One, he had somehow survived the heart attack. But...he felt younger, for some reason, so there's no way that was the case. The second possibility was that someone had turned Yoriichi into a demon to save his life—which honestly is worse than dying, in Yoriichi's opinion. He couldn't believe his brother had stooped that low. Yoriichi hadn't realized how jealous Michikatsu was until it was too late.

Speaking of his brother, Yoriichi thought back to his "battle" with Michikatsu—well, Kokushibo now. Could it be possible that it was Kokushibo—Yoriichi's brother—who had saved him? Yoriichi was quick to doubt that thought. No, Kokushibo would try to kill him every chance he got. Yet Yoriichi could not think of any other reason why he was still alive right now.

He stood up. There was only one way to test his theory.

Alarms instantly set off in Yoriichi's brain—something that warned him against stepping into the sunlight. That simply convinced him he had been somehow turned into a demon even more. Well, if Yoriichi died from the sunlight because he was a demon, that wouldn't be too bad. Death is better than being a demon, after all. And if Yoriichi survived, it would cause him much relief, and prove he wasn't a demon.

Yoriichi, ignoring the voice in his mind screaming at him not to do so, walked out into the sunlight. He expected to feel searing heat against his skin, flaring up all throughout his body. However, it did not come.

There he stood, blinking in the golden rays of sunshine. This proved that Yoriichi's theory had been wrong—Kokushibo had not turned him into a demon. So how was he alive? Yoriichi decided he'd figure this out later. Right now, he was terribly hungry, which was odd, as he'd just eaten before his fight with his brother.

Yoriichi shrugged it off and began searching for where he had been staying recently. He found he was fairly close to a Demon Slayer village. He made sure to steer clear of the villagers, as he wasn't necessarily that popular within the Demon Slayer Corps, to put it lightly.

Suddenly, someone pointed at Yoriichi and screamed, "RUN! IT'S A DEMON!"
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So yeah, Yoriichi demon AU lol. And Yoriichi can survive in the sunlight like Nezuko can because he uses Sun Breathing (not sure if that's how it works, but in this AU Yoriichi is able to be in the sunlight without burning.

Yoriichi hasn't fully transformed into a demon yet cause it's gonna take a few weeks, but here's what he'll look like when he's a full demon:

(Art drawn by me, please do not steal or repost without my permission <3)

(I ran out of ideas lol)

Word count: 967 words.