A short headcanon featuring Crazy!Chouso and his baby brother, Yuuji.
Chouso/Itadori Yuuji.
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Chouso loved his brother. Badly so. He had always loved Yuuji the moment he was brought from the hospital, wrapped in a blue blanket. He cared about his brother and protected Yuuji.
When their parents died and they were sent into foster homes, Chouso protected him.
Those who tired to harm or abuse him, Chouso made them have little... accidents. But those acts only made them move from Foster home to Foster home.
When Chouso finally reached 18, he took his 14 year old brother and ran away to Shibuya.
Chouso had to do things in order for them to survive. Yuuji knew that his brother was involved in something bad, but he didn't make a fuss about it. He just picked up Chouso's bloody clothes and washed them. He tended to his brother's wounds, whispering soft words of encouragement and love.
Chouso didn't know how their sibling love turned into something else. He started getting overly possessive of Yuuji. He found excuses to keep the teen inside, but Yuuji had school to attend. When he wasn't on a clan business, Chouso stalked Yuuji. He tended to end someone's life when he saw them talk to the pinket and show sexual interest.
Out of nowhere, Yuuji got a model gig. Don't get him wrong, Chouso was pleased and proud of his brother, but that would mean that more people would get to see the glorious body of his Yuuji.
Chouso swallowed his displeasure with a smile and just decided to be Yuuji's bodyguard, even though people saw it as a weird thing to do.
Chouso knew that something would go down sooner or later - and he was proven right.
Yuuji got attacked when Chouso wasn't home. It seemed one of his stalkers finally had the balls to do the unthinkable. Luckily, Chouso came back on time, having been feeling off, and was able to get the intruder off his Yuuji.
Whilst he was struggling on keeping Yuuji down, who was beaten and naked, Chouso used a bat to his head, fracturing his skull. With rage, Chouso started beating the man to death. Blood splattered on the walls and funiture. The dead corpse bleed on the carpet, still being beaten by Chouso.
Having gotten over his shock, Yuuji ran up to his brother and hugged his back. Chouso got himself back, panting heavily and looking like a feral monster.
Right there and then, Chouso took his brother on the bloody couch, not caring if there was a cooling body right by the corner. He filled his little brother with his essence, marking him as his forever.
Unfortunately, the cops came when the two just finished, and Chouso, still clothed, threw his coat over Yuuji, giving him modesty.
Chouso was taken into custody and charged with manslaughter, even though he was protecting Yuuji. As Chouso was dragged away from the court, he was yelling Yuuji's name, struggling against the officers.
It just took a year for Chouso's boss to do the needful and break Chouso out of prison.
When Chouso came for his brother, all bloody after killing the cops standing on guard outside his house, Yuuji just ran into Chouso's arms and huggged him.
Chouso took the young man upstairs and fucked him on the bed, making Yuuji scream and cry in pleasure while calling out for his Nii-san.
Itadori Yuuji was never heard of again, disappearing into thin air. Some speculated that his brother killed him too and had his corpse hidden, while others said that they ran away.
Either way, the two were long gone, enjoying their lives.