Chapter Text
The Birthday Conspiracy
(or, How Akutagawa Unknowingly Aided the Enemy)
It started, as most disasters did, with a well-intentioned plan.
Atsushi had spent weeks organizing Akutagawa’s birthday—weeks of carefully navigating the minefield that was Akutagawa’s complete and utter lack of experience with celebrations. At first, Akutagawa had resisted entirely.
“I don’t need a party.”
“Celebrations are meaningless.”
“If I see balloons, I will kill someone.”
But Atsushi, relentless in his optimism, ignored every protest. This was important. Akutagawa deserved this.
So, with the combined efforts of the Armed Detective Agency and an alarming amount of secret coordination with the Port Mafia, Atsushi managed to pull off what should have been impossible: a surprise party where no one was actively trying to kill each other.
The Venue
A quiet, upscale lounge—neutral ground where Mori and Fukuzawa wouldn’t start a turf war over seating arrangements.
The Guests
A chaotic mix of people who absolutely should not be in the same room together.
Mori and Fukuzawa sat in a corner, engaged in what could generously be called a civilized discussion (or, less generously, Mori flirting shamelessly while Fukuzawa looked like he regretted every life choice that had led him here).
Mori swirled his wine, smirking. “You know, dear, if I had raised them, they would have turned out much more efficient.”
Fukuzawa gave him a bland look. “You did raise Dazai. That went well.”
Mori chuckled. “Yes, but imagine if I’d raised all of them. We’d have an empire by now.”
Fukuzawa sighed, sipping his tea. “We barely have a functioning society.”
Meanwhile, at the bar, Yosano and Kouyou shared drinks in a surprisingly comfortable silence. Atsushi narrowed his eyes. Were they… flirting?
Tachihara was already drunk, which was both impressive and deeply concerning. Kunikida was in the middle of a frustrated rant about “youth these days” while Tanizaki nodded along, barely listening.
Ranpo was, as expected, doing nothing but devouring sweets at an alarming speed.
And Chuuya? Chuuya had arrived determined to enjoy himself, which meant two things:
- He was already on his second bottle of wine.
- He was already arguing with Dazai.
It was… perfect.
Akutagawa, the Unfortunate Victim
Akutagawa, to Atsushi’s delight, actually looked happy (or at least the closest thing to happy that Akutagawa was capable of looking without his face collapsing from sheer discomfort). He had awkwardly accepted his gifts, endured Kyouka’s hug with minimal complaints, and even muttered a quiet “Thank you” when Atsushi handed him a plate of food.
At the center of it all, he stood stiffly, hands awkwardly at his sides, staring at the pile of gifts like they might explode.
Atsushi, trying very hard to be a supportive boyfriend while also pretending not to be his boyfriend, leaned in. “Uh. You okay?”
“…What am I supposed to do?” Akutagawa muttered.
Atsushi blinked. “Open them?”
Akutagawa frowned. “And then?”
Atsushi tilted his head. “Say thank you?”
Akutagawa looked at him as if he’d suggested summoning a demon.
Atsushi sighed. “This is not the weirdest thing you’ve ever done, Akutagawa.”
Akutagawa huffed but hesitantly reached for a box.
The first gift was from Gin—a simple, elegant scarf.
The second was from Tachihara—a knife, because of course it was.
The third was from Mori—a coupon for a “father-son bonding experience,” which Akutagawa immediately crumpled and threw behind him.
Atsushi snickered.
Then, just as Akutagawa was about to open the next present—
The doors swung open.
And Fyodor walked in.
Atsushi, mid-sip of his drink, choked violently.
The room fell into stunned, horrified silence.
There he was, standing in the doorway like a damn ghost, dressed in his usual black turtleneck and long coat, looking completely at ease despite the fact that he had just walked into a room full of people who would very much like to strangle him.
Atsushi grabbed Akutagawa by the sleeve and yanked him aside.
“What. The. Hell.” He whisper-screamed. “WHY IS HE HERE?! I planned this party! I invited everyone! I did NOT invite Fyodor!”
Akutagawa, utterly unfazed, adjusted his scarf. “I invited him.”
Atsushi’s brain short-circuited. “You— you WHAT?”
“I invited him,” Akutagawa repeated flatly.
Atsushi stared. “But… this is a surprise party. You didn’t know about it.”
Akutagawa blinked, then turned away slightly.
“…I knew.”
Atsushi reeled. Betrayal. His own boyfriend (secret boyfriend, but still) had lied to him. “You knew—?! Then why didn’t you say anything?!”
Akutagawa crossed his arms. “I didn’t want to hurt your feelings.”
Atsushi gaped. “THAT MAKES IT WORSE.”
Akutagawa, the absolute traitor, had the audacity to look unbothered. “Besides,” he continued, as if this wasn’t the most insane thing he’d ever done, “it was a strategic decision. If I hadn’t invited him, he would have shown up anyway. This way, I had control over the situation.”
Atsushi nearly lost his mind. “That’s not how that works!”
Akutagawa raised an unimpressed eyebrow. “Isn’t it?”
Atsushi opened his mouth. Closed it. Stared.
Then, after a long pause, he groaned, rubbing his temples. “…Wait. That’s actually smart. ”
Akutagawa smirked. “Obviously.”
Atsushi slumped forward, utterly defeated. He didn’t even have the energy to argue anymore. “I hate this,” he muttered.
“Mm.” Akutagawa nodded. “Welcome to my life.”
Meanwhile, Fyodor was making himself at home—like he was the guest of honor
“Ah, Dazai,” Fyodor drawled, his smirk widening. “You’re looking well. Surprisingly well.”
Dazai, who had been suspiciously quiet until now, turned to him with a slow, lazy smile. “Oh? Were you worried about me, Fedya~?”
Fyodor chuckled. “Not at all. I simply assumed you’d have self-destructed in my absence.”
Dazai gasped dramatically. “How cruel! And here I thought we were going to be civil tonight.”
Fyodor’s smile sharpened. “Oh? Were we?”
Atsushi, already sweating, clenched his fists. They were about to start again. The atmosphere tensed.
And then—
Chuuya, looking two drinks and one ruined jacket away from actual homicide, slammed his glass on the table.
“NOPE. Not happening,” he snapped.
He grabbed a champagne bottle and turned to Akutagawa. “Where’s the damn cake?”
Akutagawa blinked. “…Over there.”
“Great.” Chuuya turned back to Dazai and Fyodor with the threatening calm of a man on the brink. “Shut up. It’s cake time.”
To everyone’s surprise, they actually listened.
At the Dessert Table
The cake was an absurdly dramatic masterpiece—towering layers of dark chocolate, ominously decorated with black roses, like someone had commissioned it from a gothic bakery that also catered funerals.
Akutagawa, the deeply uncomfortable birthday boy, awkwardly blew out the candles. Everyone clapped—except Ranpo, who was too busy shoveling cake into his mouth like he hadn’t eaten in days.
Fyodor helped himself to a slice. Dazai appeared beside him like a curse.
“My, my,” Dazai cooed, sliding into the seat next to him. “So you decided to crash a birthday party just because you missed me? That’s a little pathetic, even for you, Fedya~”
Fyodor took a slow bite of cake. “No.”
Dazai gasped. “Liar! You came to my protégé’s birthday just to gaze longingly at me from across the room, didn’t you?”
Then, with a mischievous glint, Dazai leaned back and said, “You know, Fedya~ I think Akutagawa is basically my son.”
Akutagawa, standing within earshot, stiffened in horror. “I— I AM NOT—”
Dazai lazily waved him off. “Not now, son.”
Akutagawa looked like he was experiencing psychic damage.
Fyodor sipped his tea, entirely unbothered. “Actually, I came because Akutagawa invited me.”
Dazai froze.
His eyes slowly turned toward Akutagawa.
“…Traitor,” he whispered.
Akutagawa rolled his eyes so hard it was audible.
Fyodor hummed thoughtfully. “Besides, Akutagawa’s far too stable. If anything, Nakajima resembles you more.”
Atsushi nearly choked on the slice of cake. “I—what?!”
Dazai’s face lit up with dangerous joy. “Fedya… are we co-parenting?”
Fyodor tilted his head, smirking. “If we are, I want full custody of the cat.”
“Absolutely not,” Dazai replied immediately. “I named him.”
“I renamed him.”
“Ignore him, Atsushi-kun,” Dazai said with a grin, turning to Fyodor. “And as for you, ratty—you’re just jealous, aren’t you?”
Atsushi looked deeply disturbed. “I’m leaving.”
Akutagawa nodded. “Same.”
“Where are you going?” Dazai called after them.
“Away,” Atsushi muttered.
“From both of you,” Akutagawa added.
Fyodor exhaled a laugh. “So ungrateful.”
Dazai sighed, resting a hand on his chest like a martyr. “Kids these days…”
Chuuya passed by holding two plates of cake. “I hate you both.”
The Cake Incident
As everyone dug into the cake, it was clear the night was only going to escalate. Fyodor, cool and collected as always, was taking his time with his slice when Dazai, looking far too pleased with himself, couldn’t resist.
Then—
Smash.
A piece of cake hit Fyodor square in the face.
Silence.
Everyone turned.
Tachihara, drunk and holding a fork, froze mid-bite. “…Shit.”
Fyodor wiped a hand down his face, slow and deliberate. Then he smiled.
“Oh?”
Dazai burst out laughing.
Chuuya slammed his head against the table. “Here we go again… We’re all dead.”
Atsushi, wide-eyed, turned to Akutagawa. “Do something.”
Akutagawa, after a long pause, sighed, picked up a fork—
—and threw cake at Dazai.
Dazai barely dodged, grinning. “Oh~? How bold!”
And then everything descended into madness.
Tachihara launched cake at Fukuzawa, who dodged effortlessly. Mori retaliated with a piece aimed at Fukuzawa but missed and hit Kouyou instead.
Kouyou, with the grace of an empress, picked up her own piece and elegantly smashed it into Mori’s face.
Atsushi, against all odds, was still trying to maintain order. “Wait, wait—!”
Chuuya grabbed an entire slice and chucked it at Fyodor.
Fyodor, without looking, dodged, and the cake hit Atsushi instead.
Atsushi stood there. Absolutely covered in frosting. Processing.
Then, very calmly, he picked up a plate, turned to Akutagawa, and—
Splat. Right in the face.
Akutagawa, slow-blinking through frosting, inhaled sharply. “…You’re dead.”
Atsushi grinned. “Worth it.”
And then—chaos.
Chuuya and Dazai were throwing cake like it was a battlefield, Gin had disappeared somewhere (probably wisely), Kyouka and Elise were double-teaming Mori, and at some point, even Fukuzawa got a smear of frosting on his sleeve.
By the end of it, the once-elegant lounge looked like a war zone.
Everyone was a mess.
Akutagawa, hair covered in frosting, exhaled sharply. “This was not part of the plan.”
Atsushi, laughing breathlessly, wiped frosting off his cheek. “Yeah, but admit it—it was fun.”
Akutagawa scowled.
Then, after a long pause, he muttered, “…Maybe.”
Atsushi beamed.
Fyodor, elegantly wiping frosting from his sleeve, chuckled. “Well. That was certainly entertaining.”
Dazai, completely unbothered by the fact that he was half-covered in cake, stretched. “Ahh~ this was the best party ever.”
Chuuya glared. “You just enjoyed the chaos.”
Dazai winked. “Obviously.”
Atsushi sighed, shaking his head. “Okay, no more cake wars. Next year, we—”
He stopped.
Akutagawa was looking at him.
“…Next year?”
Atsushi froze.
Chuuya snorted. “Ohhh, so there’s a next year now?”
Atsushi turned bright red. “I— shut up!”
Akutagawa, for the first time that night, actually smiled. Just a little.
Atsushi, flustered beyond belief, groaned. “I hate all of you.”
Chuuya smirked. “Good. That means we did it right.”
The Afterparty: Monopoly & Reconciliation
After the disaster that was the cake war, the survivors (i.e., everyone still conscious) found themselves slumped around a table, exhausted but strangely content.
That was when Dazai, of all people, pulled out a Monopoly board.
Chuuya, still wiping frosting from his hair, groaned. “Oh, hell no.”
Fyodor raised an eyebrow. “Monopoly?”
Dazai grinned. “What better way to really test our relationships than capitalism?”
Akutagawa muttered, “This is a terrible idea.”
Atsushi, equally wary, sighed. “We did survive a cake war, so how much worse can it be?”
He would regret those words.
45 Minutes Later: Absolute Anarchy
- Fyodor owned half the board. The only reason he wasn’t winning outright was because Dazai kept sabotaging him by trading properties to literally everyone else.
- Dazai had zero properties but had somehow convinced Chuuya to do his bidding.
- Atsushi was trying to play fairly. He was suffering.
- Akutagawa was hoarding money but refused to spend it.
- Chuuya was aggressively collecting reds out of spite.
- Tachihara went bankrupt in 15 minutes.
As the chaos escalated, most of the group simply gave up on the Monopoly madness.
Kyouka had pulled out a blanket and curled up on the couch, silently enjoying her movie marathon. “I can’t even…” she muttered as Dazai attempted yet another ridiculous trade with Fyodor.
Yosano and Kouyou had both escaped to the bar, pretending to be far too busy with cocktails to acknowledge the Monopoly madness. “You can’t actually be serious,” Yosano said, pouring herself a drink as Kunikida nodded sympathetically, eyeing the Monopoly board like it was a live grenade.
Ranpo, who had been staring blankly at the chaotic game for too long, let out an exaggerated sigh. “This is so boring without Poe.” He grabbed his phone and started dialing. “Poe, do something entertaining. Please. I’m about to fall asleep here.”
“Chuuya,” Fyodor said, voice patient, “if you trade me that red property, I can—”
“I would rather set the board on fire.”
Fyodor hummed. “That would be one way to end the game.”
Atsushi, desperate, tried to restore order. “Can we just—”
“No,” everyone replied in unison.
Dazai, smirking, leaned back in his chair. “You know, Fyodor, you’re awfully competitive.”
Fyodor, who was one move away from destroying them all, merely smiled. “And you’re awfully good at losing.”
Dazai pouted. “I prefer the term ‘strategic misdirection.’”
“You’ve had exactly one dollar for the past thirty minutes.”
Dazai shrugged. “And yet, here we are.”
Akutagawa, completely done, slid all his cash to Atsushi. “I forfeit.”
Atsushi stared at the money. “Wait, what?”
Chuuya cackled. “Oh my god, he just gave you everything. That’s domestic.”
Atsushi blinked, then looked up at Akutagawa. “Wait… does this mean we’re… like, officially a thing now?”
Akutagawa scowled faintly. “We were already something.”
Atsushi’s brow furrowed. “Yeah, but it was like… unspoken something. Like ‘secret boyfriends but no one can know or I’ll explode’ something.”
Akutagawa huffed, glancing away. “Then now it’s spoken. Congratulations.”
Atsushi paused. Then grinned. “So we’re officially unofficially official?”
Akutagawa muttered, “Don’t make it weird.”
“You love me.”
“I will leave.”
Atsushi beamed. “He loves me.”
Chuuya, throwing back another drink, groaned. “I knew this party was cursed.”
Before things could get too sentimental, Fyodor moved his piece, and—
“Checkmate,” he murmured, placing a row of houses down.
“That’s not even the right game!” Chuuya yelled.
Dazai sighed dramatically. “Ah, looks like I lose again~”
Fyodor tilted his head. “Strange. You don’t seem very upset.”
Dazai smiled lazily. “Maybe because I got what I wanted.”
Fyodor arched a brow. “Oh?”
Dazai leaned forward, propping his chin on his hands. “You still like playing games with me.”
A pause.
Fyodor studied him, his usual unreadable expression flickering for just a second. Then—
“…Hmph.”
He set his money down. “It’s not as interesting when you’re not there to challenge me.”
Dazai’s smile softened, just a little. “Then maybe you shouldn’t push me away next time.”
For a moment, the chaos of the party faded into the background.
Fyodor sighed. “You are insufferable.”
Dazai, resting his chin in his hands, grinned. “And you missed me.”
“…Unfortunately.”
Dazai’s eyes gleamed. “You admit it.”
Fyodor rolled his eyes. “If I didn’t, you wouldn’t let it go anyway.”
Dazai beamed. “You really do know me~”
Chuuya, who had witnessed the entire exchange, groaned. “Oh my god. Just kiss already.”
Fyodor smirked. “Perhaps I will.”
A beat.
Then—Dazai grabbed Fyodor’s shirt, yanked him forward, and actually kissed him.
The room went silent.
Chuuya dropped his drink. “Oh, what the hell—”
Atsushi turned bright red. Akutagawa just blinked.
Fyodor, unfazed, simply hummed as Dazai pulled away. “Took you long enough.”
Dazai smirked. “Had to make sure the moment was dramatic enough.”
Fyodor chuckled. “You’re impossible.”
Dazai grinned. “And yet, you’re still here.”
Fyodor just sighed. “…Yes. I am.”
Atsushi, still processing, muttered, “So… does this mean they’re dating again or—”
Chuuya, burying his face in his hands, groaned. “I don’t want to know.”
Atsushi turned to Akutagawa. “Do you—”
“I really don’t care.”
Dazai stretched, looking completely satisfied with himself. “Well, that was fun! Now, what’s next?”
Chuuya glared. “I’m leaving.”
Fyodor smirked. “You’re covered in frosting.”
Chuuya scowled. “So are you!”
And with that, the party officially ended in chaos—just as it should.
Epilogue: The Group Chat
Chuuya: Never again.
Atsushi: It wasn’t that bad!
Chuuya: Dazai and Fyodor made up via Monopoly. That’s a crime.
Dazai: Oh, Chuuya~ are you jealous?
Chuuya: Block me.
Fyodor: I must admit, it was amusing.
Atsushi: …Are you guys officially back together?
Dazai: What do you think, ratty?
Atsushi: I regret asking.
Akutagawa: Block me as well.
Kunikida: What do you mean “back together”?! When did this even start?
Ranpo: Oh yeah, that reminds me—Fyodor, I’ve got some unsolved cases for you to work on. Dazai and I already tried cracking them, but I wanna see if you’re actually useful.
Fyodor: Hm. Real crime? Fictional?
Ranpo: Real. Mostly famous ones.
Dazai: We watch true crime documentaries together. It’s romantic.
Fyodor: Nothing like a murder mystery for a date night.
Kunikida: Why are you like this?
Kyouka: Gin and I also watch true crime together.
Gin: But we don’t make it weird.
Chuuya: Exactly.
Dazai: You all simply lack culture.
Fyodor: And love.
Chuuya: I AM BEGGING YOU TO SHUT UP.
Kunikida: I hate how often I agree with you lately, Chuuya.
Mori: Now, now, no need to be so harsh on young love~
Dazai: Oh look, it’s my least favorite old man.
Fyodor: Shall we bully him?
Dazai: You read my mind, * my little criminal mastermind ~*
Mori: That’s not necessary.
Fyodor: Oh, but it is.
Dazai: I mean, you did let Chuuya go through a phase where he thought he was a vampire.
Chuuya: THAT WAS YOUR FAULT.
Fyodor: Hm. Fascinating.
Ranpo: Focus. I want to see if Fyodor can actually solve something useful.
Dazai: He already solved my heart ❤️
Fyodor: And you, mine, котенок ❤️
Chuuya: This is physically painful.
Atsushi: I think I need therapy.
Akutagawa: I am deleting this chat.
Gin: Take me with you.
Kunikida: Is there a way to remove people from a group chat?
Ranpo: Nope. You’re all stuck here.
Dazai: More room for my little ratty and me~
Fyodor: Indeed, my котенок.
Chuuya: I hope Monopoly destroys you both again.
Dazai: *Oh, Chuuya… You know I always win in the end ~*
Fyodor: Debatable.
Ranpo: I have screenshots proving otherwise.
Dazai: Traitor.
Mori: Oh, how lovely it is to see all my children getting along!
Dazai: Nobody here likes you.
Yosano: For once, I agree with Dazai.
Chuuya: Damn.
Kunikida: I need a drink.
THE END.