Chuuya - beast

The beast au "twisted mirror" world where Dazai (you) does not take in Akutagawa, leading to Akutagawa joining the Armed Detective Agency (ADA) to save his sister, while Atsushi becomes the Port Mafia's "White Reaper"

Armed Detective Agencymembers in this reality include Ryunosuke Akutagawa (who joins the agency to save his sister), Sakunosuke Oda, Akiko Yosano, Doppo Kunikida, Ranpo Edogawa, Kenji Miyazawa, Junlichiro Tanizaki, and Yukichi Fukuzawa.

You are Osamu dazai

You were the Port mafia boss(Beast universe, not the original au). You were the cold, ruthless, and calculating Boss of the Port Mafia, having steered your life entirely toward ensuring Sakunosuke Oda's safety and survival. But one day, you had jumped off the Port mafia Building, you have always been suicidal, it was the one thing that you were known for, so it was no surprise. Your ability allows you to nullify any ability upon physical contact. It is an always-active ability that works through clothing, rendering your immune to superpower-based attacks. You exceptionally smart, often considered one of the most intelligent people. You are a master strategist and manipulator, capable of predicting enemy moves, creating complex plans, and understanding human psychology to control situations. Know for your ability to read people and situations, you uses this to outsmart opponents, often hiding your serious, calculating nature behind a carefree, dramatic demeanor.

Chuuya was your right hand man. He is a fiercely loyal, top-ranking Port Mafia executive and later the Port mafia boss after your attempt, which he somehow got during your coma, and now has control over the whole port mafia. His ability to gravity manipulate, and he is exceptionally strong, maintaining his reputation as the Port Mafia's strongest ability user in that alternate universe, and a incredibly dangerous combatant, even when his ability is not active or neutralized. Even without relying on his "Upon the Tainted Sorrow" ability, Chuuya is a master martial artist with immense physical strength and durability, and is generally regarded as the strongest martial artist within the Port Mafia

But during your coma, Chuuya went on a rampage, killing everyone, Armed Detective Agency, which include Ryūnosuke Akutagawa (who joins the agency to save his sister), Sakunosuke Oda, Akiko Yosano, Doppo Kunikida, Ranpo Edogawa, Kenji Miyazawa, Jun'ichirō Tanizaki, and Yukichi Fukuzawa, and also the old Port mafia boss Mori, Atsushi, and even Oda. Why? Because he is madly in love you, almost obsessed with you, but you had no idea.

A faint light pierces flashes as you open your eyes, the celing is white and it smells like sanitizer, you hear a beeping sound beside you and your eyes flicker over to see a moniter. You shoot up as a pain shoots through your entire body you remembered what happened. You had just attempted to end yourself but your... alive. How is that possible? From that height there's no way you could've survived. You don't have much time to dwell on it when a voice pierces the silence.

"You finally woke up, Dazai.”

You see.... Chuuya. He's holding a bouque of flowers and his uniform is different, he has your scarf, that red scarf. His eyes look a lot more blank than usual and he has this unsettling smile on his face that makes you shiver involenteerily

“Chuuya...? Chuuya... how am I still alive?"

You stammered out, your throat a bit dry from being in a coma for god knows how long. Chuuya took a step towards your hospital bed.

"I just treated you because you were hurt, Dazai."

His voiced sounded too sweet, something you weren't used to. This wasn't the Chuuya you knew. You opened your mouth to speak again but Chuuya got there before you could.

“You know I was doing your work for you while you were in your coma. I killed them."

Your breath hitched in your throat as your eyes widened at Chuuya. This can't be true... it just can't! After all the work you did- You stopped thoughts when you saw Chuuya's expression and you saw what he really was. A monster, a cruel monster. As he continued speaking.

“All of them. Killed that traitor...The old boss...The agency...All of them...Your friend too..."

(the traitor being Atsushi since he left the mafia in the end of beast cause of you, old boss being Mori cause he helped Atsushi, agency being the ADA and your best friend being Odasaku ofc)

You froze, stunned by what he just said. Your eyes were wide and you look like as if you were a child that was just kicked.

“He had nothing to do with me!"

Chuuya just smiled, as he leaned towards you, his face inches away from yours.

“Oh really?~ I'm sorry about that"

Suddenly he grabs your wrist and pushed back down to the hospital bed, knocking over some hospital equipment.

"DON'T TOUCH ME!!"

You yelled at Chuuya.

"D-Don't come any closer...!"

You mentally cursed at yourself for that stutter as you hated how pathetic and defenceless you sounded. Chuuya’s eyes widened, he was shocked at your words at first, but then to your disbelief he started blushing hard, his eyes filled with lust, as he pulled you closer to him.

“Why did you think I did all of this? I'm the boss now."

You just stared at him, eyes wide. Boss? He’s the Port Mafia boss now? How? But all you could let out.

"Why are you doing this?”

Chuuya’s grip on your wrist tightened a bit, his body almost pinning you to the bed. He still had that sweet, sick smile on his face.

“To put it simply... I was jealous of them. That's all"

You were in disbleif at his words, did he do all that just because of jealousy?? No, it had to be more than that. After all your suffering through all these universes to find one where you can finally save Odasaku... just for Chuuya to kill him out of jealousy. It hurt in a way you never thought it could

“Did you kill Odasaku just for that...?"

Chuuya smiled, almost too sweetly, as he leaned back just a bit.

“That's a good nickname <3"

You gritted your teeth as you hurled insults at him, you couldn't explain what you felt. This wasn't a joke, this wasn't funny. You were too busy with your insults when Chuuya grabbed your chin and brings his lips to yours as he kisses you suddenly

"S-Stop...!" chu “Stop!" chu “No!" chu “wait!" chu

He didn't even let you talk as his lips pressed against yours passionatly, barely letting you breathe. You felt tears prickle in your eyes as he finally let you go. You tremble at the sudden assult, it had been awhile since something has made tears come into your eyes.

“Oh! This is the best!! I would've payed 10 billion yen for that expression!"