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English
Series:
Part 2 of Throwing Chairs is a Love Language™
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Published:
2026-04-13
Updated:
2026-06-04
Words:
10,881
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3/?
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61
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125
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Double Black Double Back

Summary:

“Well…I guess we should start packing?” Chuuya remained very still for a moment, stunned at what had just gone down a few seconds ago. Dazai looked questionably up at him with his large puppy eye, successfully snapping the redhead out of his daze, and was then thrown ungraciously onto the floor.

“What the FUCK just happened.”

 

OR:

Chuuya and Dazai are sent on a mission to Musutafu to take down all the Pro Heroes. Akutagawa and Atushi, for reasons unknown, are tagging along. What the hell is going to become of this?

 

sorry i do terrible summaries pls js trust T~T

Notes:

Hello, and welcome to my latest fic! Some quick things before u read :)

-TWs are always in chapter summary cuz there are A LOT but mostly all should be mentioned in tags so if u arent cool with any of those, this fic probably ain't for u

-Will update inconsistently! I'm trying to do better on that but I tend to switch up on fandoms pretty fast. The more comments tho the faster the chapters will be...👀

-There is a soulmate AU, but its not the whole plot! Basically the premise is just that if one of them writes on themselves, the writing will appear not only one his/her/their body but on the other's as well. In this case, an example would be, say, if Dazai wrote: "Slug!! Where r u???? (; 0_o )" on the palm of his hand, then the writing would not only stay there but also appear on Chuuya's palm until Dazai washed it off his own hand! It works the same vice versa :) also, doesn't go away after soulmates are found for the sake of the fic cuz its established real-deal skk

-POVs will alternate between Chuuya and Dazai, although at some points it may be difficult to tell the POV. It should clearly state the POV in the chapter summary though so if anything seems out of POV or incorrect, please lmk. Also, I might occasionally throw in a different POV if I find it necessary or if I just wanna have some fun experimenting with it but it should also be stated in ch. summary whose POV!

-As much as I would love to make all the characters personality-accurate, I'm not personally the author therefore its impossible. Also, the ship is supposed to be a little more soft than they are in canon so please don't be angry abt that...I'll try to be canonically accurate otherwise, but I also haven't watched BSD since I lost my Prime account a while ago, so events might be inaccurate or completely out of canon (fanon). You might also notice some minor changes in other stuff which will be explained as needed.

-Intelligence is a real thing! Dazai has it, Nedzu has it, hell--even Chuuya has it! That does not imply that I am intelligent enough to supply them with intelligent POVs. I will try my best, but I'm not exactly as genius as a talking mouse or a teen mafioso. If you have any reccs to make the intelligence better, please lmk in comments!

-This was inspired by many amazing fics and authors who you HAVE to check out. Please look at Must_have_been_the_wind- because this fic inspired this writing. MHBTW's writing is, by the way, is TO DIE FOR. Please also check out AnxiouslyShipping because they made the fic that gave me the soulmate au idea! Its here.

I think thats enough for now! Happy reading folks :)

(See the end of the work for more notes.)

Chapter 1: Mori's in Deep Shit for This One

Notes:

First chapter!! Yesss it’s finally out :) this one is a bit less than 4k words, sorry for so little I js wanted to get this first chapter out and had a good stopping point. Please don’t expect high quality bc this isn’t beta read and I wrote it while playing cookie run kingdom 😓

TWs:
-Dazai’s big beautiful glorious eyeball
-Mori petting Elise
-aka nothing really for this chapter but if you think there’s more I should add please lmk!

(See the end of the chapter for more notes.)

Chapter Text

“That was more uneventful than when we killed off half the FDA! And these “heroes” have the gall to assume Yokohama is in need of their protection? I’m laughing my fucking ass off, Chibi.” Dazai sighed, lightly dusting off his trenchcoat and promptly collapsing onto his partner’s back, said partner grumbling and clasping the brunette’s wrists as he began to drag the other out of the room as he would a particularly unwieldy sack. 

 

“Shut up Mackerel, you and The Boss got what you wanted so that's that. Wait–we did have your useless mentee collect the live ones, right?” Chuuya paused then, lifting Dazai—concerningly almost weightless now—off his shoulders and placing the boy gently in front of him. A wide, dark eye stared back at the redhead, and for not the first time (shamefully) the boy was caught in a state of paralysis, victim to a starless sky expanding over his vision. That starless sky, of course, being Dazai’s beautiful eye. Shit, if one of his eyes makes me this dysfunctional, I’d hate to see the other…Chuuya thought distantly before reality came crashing back in a full-force when the aforementioned partner perked up and turned, whistling down the dank underground sewer tunnel. The sound echoed, bouncing away into the darkness, and for a minute Chuuya wondered if Dazai’s new pet had heard anything at all–although, those thoughts were soon interrupted by light footsteps and splashing grey water. I am never letting Osamu pick where we take down our targets again. The redhead shifted in his wet socks, thoroughly discomforted at the reminder of what exactly they were soaked in. Dazai on the other hand, long black trenchcoat dipped in the murky liquid covering the ground, seemed not at all bothered by his soiled shoes or coat. 

 

“Black Wraith-Sensei! Has the mission been completed? Do you require assistance with something?” A scrappy-looking kid, only a year or two younger than Chuuya himself, sped down the tunnel and skidded to a halt in front of Dazai, splashing grey water on both Chuuya and his partner. The younger boy took a knee, head bent slightly to stare intensely at the bandage boy’s scuffed and water-logged shoes, which didn’t very much warrant a laugh but received one anyway.

 

“Damn Mackerel’s got a fanboy! Oh man, a little slave! And I thought you were joking when you said the little motherfucker kowtowed to you more than The Boss to Little Goldilocks Princess!” Chuuya wiped at his eyes as he calmed down, tears of laughter staining small streaks down his face. The “fanboy,” on the other hand, looked mortified—scared half to death as well. “What’re you starin’ at, kid? Never seen a PM Executive laugh before?” Chuuya found himself smirking as the little runt shook his head slowly, still in a state of shock. “Yeah, that tracks I suppose. I mean, just the knowledge that one day shitty Mackerel will be in my presence is enough to have me considering the idea of leaving Yokohama! Can’t imagine how anyone else puts up with him.” Dazai gasps, hand clutching his chest as he looks woundedly at Chuuya. The boy staggers back against the sloped wall of the sewer tunnel but quickly steps forward again with a disgusted expression as the wet cobblestone considerably dampens his already less-than-mint-condition coat. Sighing, he turns back to face his mentee and pats him on the head. Well, “pats” would be an understatement, as it was more akin to simply tugging on the boy’s hair.

 

“Mission’s done, little doggy! What’s being done with the dead bodies?” Dazai sing-songed, though Chuuya could tell it was fake. Darker and more ominous than what he used with Mori or Ane-san. Goddammit Osamu, didn’t I tell you to go easy on the brat? Chuuya sighed internally, hoping the kid’s training wasn’t as rough as he was imagining. 

 

“The dead bodies are being burned just outside, the event scheduled to finish just before daybreak to avoid witnesses. Oh, and I assume you’d like to hear of the living ones?” Said kid reported, a glimmer in his eye as Dazai grinned. Don’t get too used to it. Cynical thinking might have been Chuuya’s ability, if not for the obvious. Reading Dazai like an open book could have been his second. 

 

“You know me too well, little emo boy! More useful than that awkward ability of yours for sure. Maybe I won’t shoot you today…Now, where’s my report?” Just as Chuya had predicted, Dazai’s tone turned sour and he took up a look of disdain and disappointment, as if his trainee had purposefully withheld the information. 

 

“S-sorry Black Wraith-Sensei! Of course, yes, um…” The boy paused to cough feebly into his sleeve before straightening slightly, rising from his kneeling position. “Well, the regular ones, by which I mean the “quirkless,” as they’re called in the rest of Japan, are being taken to holding cells as hostages. The ones with average, err, quirks, are being taken to special cells near The Boss’s lab for…research, and the ones with valuable quirks are apparently in Japan’s national top-ten hero chart. After some minor research done from my portable mobile device, I was able to identify all said heroes and their abilities—...quirks, as well as their specific rankings. They’ve been drugged in case their injuries weren’t severe enough to have them unconscious the entire ride over, and are on their way to Black Wraith-Sensei’s chambers. Not, um, his living quarters, of course. His other chambers. 

 

“Wonderful, I’ll have a great time with them! Isn’t that just amazing, Chibi?” Dazai grinned, collapsing onto Chuuya who barely managed to stabilize the both of them in time to avoid crashing into the soiled water below. He grunted, muttering his complaints of the other but allowed the boy to clamber onto the red-head anyhow as the three children began heading down the tunnel—Dazai piggybacking on his partner, of course, because how else could it be?

 

“God, can we cut the crap with these codenames? ‘Black Wraith’ just makes the damn mackerel sound like Satan!”



Chuuya found it only a little annoying that Mori had called for the mission report three minutes after they had arrived. It was only a little inconvenient that he could not type a fully detailed report of the events and outcomes in three minutes. It was only slightly disadvantageous that the printer could not print said magical report in thirty seconds. It was only very slightly baffling that Dazai had somehow managed to do all of the above with ten seconds to spare, which he spent stealing Chuuya’s hat and forcing him to chase the bandaged boy all the way to Mori’s office with two seconds to spare. Dazai was, though embarrassing to admit, faster than Chuuya by far without the latter using his ability, and Chuuya’s ability was a bit overused at the moment. The guy can work fast as fuck when he feels like it, the lazy prick. Just as Chuuya peeked at his watch, the office door swung open and Elise waltzed inside, a fawning Mori trailing after. Not a second off schedule. The redhead sighed, finally managing to swipe his hat back from Dazai. 

 

“Ah, there they are! My infamous Sokouku in the flesh. How lovely you both look this morning.” Oh yeah, I guess it’s morning now. Chuuya glanced out the small office room window at the slightly lightening skyline through the thick haze of car and factory fumes, nighttime city lights beginning to dim. Mori took a seat in his office chair, a large one made of cushion and black film that spun on well-oiled wheels. Elise, rolling her eyes, plopped down on the man’s lap as Dazai stood hesitantly, inching his report across The Boss’s desk before hurriedly re-taking his seat beside Chuuya. This time, a little too close to Chuuya. He sighed. Mori scanned the papers for a minute or so before smiling contently. “Great work, Dazai! I always had faith in your paperwork skills, you know.” Dazai smiled, though it looked more like a grimace. Doesn’t this dumbass boss know Osamu hates compliments? Being the one that practically raised him, the idiot should know. 

 

“I learned from the best, Mori-Sensei!” The bandaged boy chirped. Mori grinned, taking out a folder and slotting the report in neatly before tucking it away. “Now, what did you really call us in here for?” Goddammit, of course there has to be another reason. How the fuck does Osamu even figure this shit out? As if reading his mind, Dazai turns to Chuuya with a sly grin. “Well why else would he request specifically the both of us to report back, and at such a specific time as well? Usually it’s simply expected that one of us types up a report and brings it in once we’re done, no scheduling or questions asked. Y’know, using your brain a little more might do you some good, Slug!” Jesus, I'm an idiot. Chuuya decided to retaliate anyway.

 

“Shut up, shitty waste of bandages!”

 

“Now, now, boys! Settle down. You’re correct as always Dazai, there is a reason I requested you both in such a hurry. Now I wonder…let's see if you can figure it out!” Oh man, am I seriously gonna have to sit through this? Chuuya had better things to do than listen to Dazai ramble about what the hell Mori wanted to discuss with them. Elise looked equally forsaken, slumping down slightly and closing her eyes, tiny pale arms crossed over her chest. If only I was allowed to do that…man, I'd be out like a light! It wasn’t true, but the idea still made him envious. Next to Chuuya, Dazai sighed and leaned back. 

 

“Ok, fine. Well it’s obvious you want us for a mission, and considering how many Sokouku missions you’ve been sending us on—even ones we could have done solo—I’m guessing you’re trying to prep us for something big that’ll take a lot of time. Considering we’ve been doing these missions mostly alone, I’m thinking this is a Sokouku-thing-only. Ughhh. Now as for the specific mission, most of these missions you’ve been sending us on recently are to take out the Pro Heroes along the border, especially the Musutafu border, so I’m guessing we’re going to Musutafu for a hero wipeout. Although, there’s some sucky politics to this. From what I know, there’s this agreement with the Japan government and the Yokohama government, which I guess they’re separate. Um, well the weirdos outside Yokohama apparently all have watered-down abilities or something that they call “quirks.” I heard they branched off from abilities, but are more intertwined with the person’s DNA. Welp, anyways, Yokohama is about the only place on earth left with ability users and although rare here, most of the world’s population everywhere else have quirks. The thing is, though, that most of these quirks are pretty lame and would never stand a chance against an ability user, no matter how dumb the ability. Hence why all the ability users were squared away to Yokohama, a law preventing any travel to and from the place or interaction with the outside world at all beyond basic trade-“

 

“Remind me why the fuck I’m getting a political history lesson from this Mackerel?” Chuuya crossed his arms, glaring at a bemused Dazai. 

 

“Now now, Slug. It’s not nice to interrupt people! Bad dog. And as to answer your question, I was filling you in on important information for our next mission! I was also just about to get to the part directly related to our work, so if you’d allow me to finish…” He looked expectantly at the redhead and, with a sigh and a “I’m not your damn dog” from said boy, the brunette continued. 

 

“Well as I was saying, this rule also prevents heroes from entering Yokohama.” Oh. Well I guess I know what I’m doing now, huh. “Hah, you get it Chibi! Finally used that brain of yours, eh?” Bastard noticed I figured it out? I swear to god his ability is reading minds. They were only ten minutes into the meeting and it was already giving Chuuya a migraine. All he could do was pray it’d be over soon. “But recently, said heroes have seemed to be ignoring that rule. Although at first it was a disadvantage for Yokohama, it’s become more and more useful for the government to keep things orderly. Without Pro Heroes toppling buildings every time a guy plants a bomb, the place has been accelerating in many areas such as healthcare, education, and entertainment.”

 

“Wait wait wait, hold up. Sorry I’m not a genius like you Mackerel, but why the fuck would Pro Heroes be randomly deciding to break this law their government put in place for their own safety? Sounds to me like you just fumbled, dumbass.” Dazai giggled, stretching slightly and adjusting the bandages on his arm idly. 

 

“Stupid hatrack, of course it makes sense! There was no fumble.” And this bandaged fucker has to nerve to grin at me like that— “You see, Pro Heroes work directly under the government. There’s no betrayal going on here, the government is sending them here.”

 

“But why, Mackerel? Why the fuck would the Japanese government decide to break their own law out of the blue?!”

 

Because, Chibi, Yokohama is still technically part of Japan.”

 

“So?? What the fuck does that have to do with anything?” Dazai sighed and rolled his eyes impatiently, as if trying to explain why there weren’t trees on the highway to a toddler. 

 

“A Pro Hero’s job is to keep criminals contained and the crime rate low—kind of like our job, but more…legal. Well, Japan has a pretty low crime rate. Yokohama, though…although we keep actual criminals in check, the Port Mafia itself is organized crime. The police don’t do shit.”

 

“…So our crime rate is sky-high and Japan is pissed about it because it’s bringing down their reputation?” Dazai nodded, huffing.

 

“And it’s not even a legitimate concern! Actual crime in Yokohama is handled, even though we kill the guys instead of locking them up. Hell, even the ADA pitches in sometimes! Also, we are like—the one outlier in Japan. On a graph with the crime rates of all the cities in Japan, taking the average could be either the median or the mean. Since Yokohama is an isolated city in the higher rates while all the other cities are collectively in the lower ranges, the only sensible way to take the average would be to use the median, because the mean would dramatically change the average just based on that one outlier, but no! The government has to use the worst and most inaccurate way to find the average-“

 

“How is the Japanese government that stupid, though? I mean, you figured that out in like two seconds, how they were taking the data wrong, but like really? Even I could have realized their mistake after a minute.”

 

“It’s simple, Slug. They’re looking for a reason to barge in and claim Yokohama.”

 

“HAH?” This was the most  shocking thing Chuuya had heard all day. It shocked him more than anything else in the last week, actually, and that was always saying a lot when one is partners with the Demon Prodigy. 

 

“Yeah! And telling citizens that Yokohama is a place for criminals and mayhem that needs saving not only brings down our “crime rate,” but it’s basically advertisement for all those Pro Heroes.” By now, both boys were seething. It was much more difficult to tell with Dazai, who always kept a neutral or playful demeanor, but Chuuya could tell with how he fiddled with his long, bony fingers and tapped his small foot on the tan carpeted floor. Chuuya’s rage, on the other hand, was far less concealed. 

 


“THOSE FUCKING SONS OF BITCHES. I’M GONNA MURDER THEM! THEY THINK WE CAN’T TAKE CARE OF OUR OWN CITY AFTER CASTING US OUT BECAUSE WE’RE TOO POWERFUL? WHAT THE FUCK, YOU HYPOCRITES!” Mori sighed, petting Elise’s hair lightly.

 

“Calm down, boys. Dazai still hasn’t finished answering my question, that being what your mission is.” Dazai, rolling his eyes, laid down, long thin limbs sprawled across Chuuya. Just like magic, the redhead was immediately calmed and settled back down. All it took was one touch from Dazai and the other boy relaxed, the tingle of Arahabaki under his skin fading. At first he had tried to convince himself it was simply Dazai’s quirk, but even Chuuya was smart enough to know better now. 

 

“Well, I think by now it’s pretty obvious we’re supposed to stop heroes from entering Yokohama, but since we’re children—and hitmen at that—I doubt you want us participating in any political discussions. Meaning…our mission is to dismantle the hero society. We’re supposed to do what we signed up for when entering the mafia, kill them all. But of course why only send two kids in instead of the whole board? There are tons of heroes after all. Well, the more heroes are killed, the more people will aspire to be heroes and rise to take their place and, hence, revenge. So you’re essentially asking that we dismantle people’s ideologies of heroes. Oh, and judging by the place, Musutafu, home to the greatest hero school internationally, and the fact that you chose two kids for the job, indicates it’s an undercover mission at UA Highschool where we’re somehow meant to convince all the aspiring heroes there not to become heroes as well as convince the public of the same thing, all the while murdering said heroes. And keeping the entire fiasco under wraps, as well—not that it could ever be executed in another way, of course. But Mori-Sensei, isn’t this all a bit excessive? With the force of the Port Mafia, teamed with the ADA and perhaps the GSS since we retain a common goal, we could easily take down every person in Japan with a “quirk,” let alone just the ranked Pro Heroes.” 

 

Chuuya was only partly paying attention to Dazai’s question, his mind still reeling from the egregious amount of information that had just been explained. How in the hell did Osamu figure that out?! He knew he wasn’t stupid, but in that moment he felt just a slight tinge of doubt.

 

“Well, if you want the honest reason…I need a good and long break from the both of you and your shenanigans, and this is the longest possible route to be taken. Also, it’s been a while since something teased your brain, Dazai, or gave Chuuya pause. I figured it’d be a good exercise to sharpen your abilities, minds, and teamwork capabilities!” Elise chuckled, the gesture sounding wrong coming from her—maliciousness crept into her every act, try as she might to hide it. 

 

“Rintarooooooo…” The little girl teased. Oh man, this isn’t gonna be good…Was Chuuya’s last thought before Elise spoke the cursed words he was expecting. “Are you sure  you wanna leave these two alone on a mission for that long? I thought you didn’t like how close they got to fucking on all their shared missions!” Dazai burst into laughter as Chuuya began to cough profusely, face turning red.

 

“Elise! Don’t speak like that, please! These are two of the best assets to the Port Mafia we’re discussing. They can do whatever…they enjoy…” Another cough from Chuuya momentarily interrupted the man, to which he didn’t seem to mind. “As long as it doesn’t interfere with work. Or their health.” Dazai had fallen off of Chuuya’s lap at that point, rolling around on the floor as he wiped tears of laughter from his eye. 

 

“Thats disgusting.” The redhead muttered under his breath. Dazai rolled his eyes and picked himself up, trying to catch his breath as he laid back down on Chuuya, who was now very keenly aware of the boy on his lap. 

 

“Wait, how long is this mission expected to take? Elise said it’ll be a while, but I need an estimate of how many days in hell I'll have to endure with this Mackerel.” Ignoring Dazai’s offended “hey!”, Mori pulled out a file from a drawer in his desk, brisking through it for a moment before shutting it closed and sliding it away, seemingly satisfied.

 

“A minimum of six months, I'd say.” If anyone was making noise before, that sentence had certainly shut up the entire room. Even Elise seemed surprised, and to say Chuuya and Dazai were underwhelmed would be not only a lie, but an absurdly exaggerated one. 

 

“Did you want the Port to collapse, Mori-Sensei?” Dazai asked in an almost completely blank tone, the only tone Chuuya couldn’t get used to. He pinched Dazai’s cheek, causing a little scuffle that Mori eventually ceased by clearing his throat and knocking lightly on his desk.

 

“I understand that it’s a long time to be away, and that the Port won’t be able to function as smoothly without you, but I will remind you that the Port Mafia is one of the strongest organizations in Japan, and that has been established since before either of you were even born. We’ll survive over here arguing with the government over shipping taxes and trying to get Akutagawa to stop riding Weretigers. Oh, and speaking of—Akutagawa is actually going to be accompanying you! And his little friend Atsushi as well, from the ADA. They were especially insistent on helping out, seems no one particularly likes the Pro Heroes. Anyhow, you’re all leaving in three days. Happy packing!” And with that, Elise and Mori hopped up from their seat(s?) and promptly left the room, not bothering to wait for a reaction from the two boys they’d left behind.

 

“Well…I guess we should start packing?” Chuuya remained very still for a moment, stunned at what had just gone down a few seconds ago. Dazai looked questionably up at him with his large puppy eye, successfully snapping the redhead out of his daze, and was then thrown ungraciously onto the floor.

 

“What the FUCK just happened.”





____________________T - T____________________



Later that night, Chuuya would notice pen being scribbled onto his arm. What the hell do you want, Mackerel? Dazai wrote as follows:

 

Chibikoooo!!!!!! b(*^▽^*)b

 

I thought of all the things we need to pack (╹◡╹)sent it to aku alr cuz PHONE but neither of us have atsushis # (; ̄◇ ̄) u have connections in the ADA right??? (Chuuya did not, in fact, have connections in the Agency) welp anyways send the list to weretiger boi ty!!

 

THE LISTTTTT:

 

-7 pairs of ur uniform :))

 

-7 pairs of pjs

 

-7 pairs of other stuff like socks and undershirts/pants 

 

-i think they have soap and stuff but being a toothbrush and a hairbrush for ur beautiful lockes \(//∇//)\

 

-a couple pocketknives. They dont allow much else on the plane and workarounds for that r too much effort when we could js get stuff there (and yes stupid chibi we have to fly on a plane bc we r very far from Musutafu ( ͡° ͜ʖ ͡°) )

 

-basic entertainment ig and uhhhh whtv else u need :) but only if it can all fit in one carry on bag!! Mori sensei said only 1 suitcase and 1 bag, he gave us matching ones!!!(๑˃̵ᴗ˂̵)



Bye mr soulmate gn ly :)))) 

 

Chuuya found himself a little flustered and a little annoyed, but surprisingly, he was grinning ear to ear, and knew there was only one way to respond. He took a nice blue pen from his desk drawer (it had been agreed, so as not to cause confusion, that Dazai would write only in red ink and Chuuya only in blue) and wrote on the back of his hand:

 

Shut up mackerel its late asf

 

Gn lyt ♡〜(ゝ。∂)

Notes:

What didja think?? Is it any good?

Kudos and comments are fuel for the fire I will keep smoking out chapters if y’all gimme praise✨👍

Have a wonderful day/night, this is RumInTheFandom at 11:01pm signing off! See u all on the other side :)