An Irreversible Reaction [FIC]

[notturnito]

Title: An Irreversible Reaction
Fandom: Bungou Stray Dogs
Rating: G
Pairing(s):Mutually pining Atsushi/Tanizaki (Junichirou). Warnings: Mentions of past child abuse, mild hurt/comfort, but this is very fluffy!! Tanizaki is going through lengths to make Atsushi feel accepted in ADA!! Pre-slash.
Notes: They are very awkward around each other, fumbling and blushing. Tanizaki and Atsushi bond over their sisters.

---

For as long as Tanizaki can remember, he has taken care of Naomi since they were at a very young age.

The concept of loneliness has never been an issue to him; only a mere impermanence, floating in and out as if the clouds on a sunlit sky. He has Naomi. She is a constant presence in his life that alleviates the swelling of emptiness when it does happen. Even after Light Snow had manifested, even after his parents had kicked him to the curb and shut the door to his face in fear of having a child-monster; Naomi didn't do any of that.

She had followed, despite the danger. She had stayed. She still does.

Sometimes Tanizaki thinks about what he would've done if Naomi hadn't been there. It is unthinkable. Something out of the frame of his mind. It is broken when Naomi returns to his side, cheerfully asking after his day. Whenever that happens, Tanizaki doesn’t return to that train of thought, letting it trail behind him as does the afterimage of Light Snow.

Until Atsushi, that is.

Dazai had debriefed all the members of the Armed Detectives Agency of his newest candidate before the day of Atsushi’s entrance examination. All Tanizaki caught from Dazai’s words were Atsushi’s name, orphan, and Ability-user.

“A dangerous Ability-user, in fact, and goddamnit, Dazai—what are you thinking?” Kunikida had bellowed from his side of the table. “We can’t just accept any strays you picked up on the streets!”

“But it’s only right, isn’t it, Kunikida-kun?” Dazai’s eyes had glinted with the usual amusement he always reserved for Kunikida. Then something shifted, his grin fading out to give way for a smile that Tanizaki couldn’t quite pinpoint on, soft and gentle. Kind of aching.

“He’s an Ability-user, after all. There’s no better place for him to be.”

Kunikida must had noticed something in that phrase, something Tanizaki wasn’t privy to. His lips thinned into a fine line, but no other protests came after. They had reached an agreement between them.

All that’s left was Tanizaki’s part of the job.

He approached Dazai after the meeting had ended, Yosano getting up first to close up the infirmary, then Kunikida was the last to leave, reminding Dazai to shut off the lights. Tanizaki had stayed, because no matter the fondness Dazai had latched onto for Nakajima, he remembered ‘Dangerous Ability-user’ and opted to stay back for… guidance. Anything.

Dazai ended up inquiring him first.

“Not leaving, Tanizaki-kun?” He had smiled, humor-edged and fine. He seemed to have noticed Tanizaki’s purpose on staying behind and took amusement in it, patiently waiting for him. It only served as embarrassment on Tanizaki’s part, because there’s nothing so scary about this, really.

“No,” he admits. “I was wondering if I could ask you about the newest candidate, Dazai-san.”

“Of course.” He looked like he had even expected the question. It made Tanizaki wonder if he were transparent to Dazai, easy to read and dissect. Tanizaki spent a moment to wonder how it would be if he used Light Snow on Dazai; if the man would notice the other layer on his eyes. The thought dispelled easily.

He spent another moment to gather his wits and tried.

“This person…” Tanizaki hesitated. “What is he like?”

Dazai’s eyes shone, bright with mischief. “Curious much, Tanizaki-kun?”

Tanizaki couldn’t help the small, wry smile forming on his lips. “Only when it comes to dangerous Ability-users.”

“Oh, you don’t have to worry about that,” Dazai answered that easily, waving his hand without a second thought. “He’s harmless when he’s not using his Ability.”

The exhale Tanizaki gave out was flat out relieved.

“I see…”

“But that’s not quite answering the question, is it?” Dazai gave a small hum, playful. He looked up, letting the light of the room trace the slope of his beautiful profile. “Kind, if I may say so. At least, kind enough to pull someone of a river even by the end of his ropes.”

For a while, he didn't say anything. Only the quality of his gaze changed into something pained. It disappeared when he looked straight into Tanizaki. “I think you both will get along.”

“Is that so…”

Dazai smiled, brushing away past him. He hovered by the doorframe, just one moment of stepping out. “Get some rest, Tanizaki-kun. You have a big part to play, after all.”

And with that, Dazai left too.

***

Atsushi was eye-catching. From the first moment he had set foot into the Agency, his appearance had been striking, lasting quite an impression. Tanizaki had watched him stumble over his steps to approach him, had seen his white hair and choppy strands, had gotten a glimpse into Atsushi’s eyes and had thought, oh.

Then, he had watched Atsushi dive in to secure himself over the fake bomb, ready to sacrifice his life over a bunch of people he hadn’t known before.

It’s hard not to like him, after.

The realization that Atsushi is an orphan who came from an orphanage only pricks within Tanizaki’s consciousness during a dinner together between three: him, Naomi, and Atsushi as additional guest. He is invited due to Tanizaki’s guilt over the entrance examination incident and Naomi’s insistence on knowing further their newest member. Atsushi doesn’t speak too much about his past and to his credit as well, he doesn’t ask about Tanizaki and Naomi’s.

Tanizaki is in the middle of saying something to Naomi, when Atsushi speaks up, voice sounding slightly off.

“Tanizaki-san and Naomi-san have a very close relationship, huh?”

Tanizaki pauses. Beside him, Naomi does the same, her laughter receding into a smile. When Atsushi notices that both of them are looking at him, he recoils, startled.

“Sorry,” he grimaces, hands pulling at each other. “That’s a bit weird, isn’t it.”

It’s Naomi who laughs. “Not at all,” she waves it off. “You took us a bit by surprise, that’s all.”

The lines of Atsushi’s shoulders reflect relief. This is not the first time Tanizaki has wondered what had happened to him, long ago, before his recruitment into ADA. He takes his time sharing a glance with Naomi, noting from her slightly-raised eyebrow that she must’ve noticed the same as well.

“Yes,” Tanizaki answers, returning his gaze to Atsushi. “Naomi and I—we’re close.”

Naomi grins. “After all, Brother has taken care of me from a very young age.” She gives him a light punch on his shoulder. Her smile when she meets his eyes is soft. “I’m grateful for that.”

No matter how many times Tanizaki has heard it all before, he still swells from the warmth it brings to his chest. Often has Naomi remarked that she’s grateful of him, especially when Tanizaki was submerged under the weight of failed cases, under sub-zero state, but Tanizaki thinks that he’s the one who should be grateful instead. He meets Naomi’s smile with another of his own, hand raising up to carefully pat her head.

Naomi indulges him for a moment only, before swatting his palm away with a cheeky grin.

“That must’ve been nice,” Atsushi remarks. Tanizaki turns to see Atsushi staring at them, gaze remote. He hasn’t known him well enough to recognize the odd expression in Atsushi’s eyes, only that it makes something ache within him, like an echo.

That’s when he remembers where Atsushi came from.

“It is.” Tanizaki hears Naomi agree, knowing that if he were to turn right now, he’d find Naomi giving him yet another questioning glance. But he thinks to Atsushi, and his mind itches with the questions he wants to ask. There’s something about Atsushi that makes Tanizaki unable to ignore the urge to prod around on his own.

“What about you, Atsushi-san?” He asks, watching the turn of expression Atsushi takes. “Were you close with anyone, before?”

It takes a while for the question to truly sink in. Then, Atsushi turns rigid, the expression in his face darkening. From the way he nearly curls into himself, eyebrows furrowing, Tanizaki finds his answer.

Before Tanizaki can do anything to alleviate the situation, Atsushi bitterly smiles.

“No one exactly wants to be friends with-” his breathing pauses, and with that, Tanizaki’s heart hitches. “With a beast of calamity.”

Tanizaki knows.

Being an Ability-user isn’t something amazing, contrary to what other might believe. It gifts you the unimaginable power outside of human comprehension, operating within boundaries undefined to human logic. No Abilities are quite the same, or at least, that’s what Tanizaki has known from the experience in his life. It can be useful, handy at certain times. It can also be awful, awful in the old sense, bringing misfortune to those who wield it.

From the looks of his past, Atsushi falls into the latter category.

It’s everything Tanizaki can identify with.

But he imagines being thrown out of his home, alone, without the assuring weight of Naomi’s presence beside him. He imagines wandering the streets purposeless, without a reason to live; only with the company of his own mind to fashion Light Snow as his defense. He sees Atsushi, commits the sight into memory. To the rigid lines of Atsushi’s shoulder, his bitter smile, to the foreign look in Atsushi’s gaze when he looks to the sight he made with Naomi, like a pang to the heart.

It occurs to him just then that it might be longing.

All at once, Tanizaki’s chest constricts. He has only known this teen in front of him for a short time but when Tanizaki sees the hunched display of Atsushi’s posture, he wants nothing else but to take some of the burden of his back. He wants to extend a hand for this lonely boy, whose despairing longing for a friend—moreover a family—must’ve been guarded tightly by his fear, crushing him inside.

“You have us now,” Tanizaki manages to breathe out, his sentence snapping Atsushi’s head towards him. He flushes as he feels Naomi’s gaze on the side of his face.

“I mean,” he stammers aloud, hands flying. He notices that Atsushi is staring wide-eyed, surprised. It grounds Tanizaki, it lets him strengthen his resolve. “At least, you’re not alone now. You’re a part of the Agency. You’re one of us.”

With trembling heart, Tanizaki offers Atsushi a smile. He waits for the answer.

Atsushi’s eyes are wide, looking at him before sliding to Naomi asking for confirmation. It’s almost a surprise to Tanizaki that he manages to think, fleetingly, like a slip of the thought; that Atsushi has beautiful eyes. Assuaging the thought into the back of his mind, he turns to Naomi.

It’s Naomi’s smile that ends every question. “Yes,” she says. “You’re one of us now, Atsushi-san.”

Atsushi is still staring at them.

“But-” he begins, halting. “I’ve hurt you both. You’ve been hurt because of me.”

It takes a moment for Tanizaki to realize he’s referring to Akutagawa. He shares a glance with Naomi, reads the obvious fondness on the line of her expression, knowing that Naomi would be able to read the same thing on him.

“Really, Atsushi-san?”

Naomi giggles at the surprise on Atsushi’s face, just barely before Tanizaki says, “Well, it’s Akutagawa who got us all injured…”

“But—”

“And we’re all better now thanks to Yosano-sensei’s treatment,” Tanizaki can’t help the shudder from what the words bring to mind; the glint of Yosano’s machete, looming over his head.

Naomi waves it off. “It’s really nothing at all, Atsushi-san. We’re made of tougher stuff than you might realize.”

“So,” Tanizaki says. “We’re fine, between us, really,” belatedly, he adds, “Atsushi-san.”

By the end of the silence in their wait, a smile finally quirks up on Atsushi’s lips. It is hesitant, just as the smile Tanizaki offers him. But anyone can see the obvious longing, the hopeful quality marring it; a child too afraid to take the hand offered to him. Sincere, in every words can convey.

“You don't have to be so formal with me,” he says.

There’s no reason to say no.

***

Kyouka comes to them just two weeks after Atsushi’s arrival.

The Agency is a place where people wouldn’t ask about your past if you don’t open up about it. President Fukuzawa is a benevolent man; kind. He’s made a safe haven for people like Tanizaki, people who don’t have anywhere else to belong, as long as they’re willing to show a spirit befitting of the Agency’s motto to protect the weak and fight for justice.

That includes people who are willing to shed their past misdeeds, deciding to forgo a better life instead.

She had looked very small, her head propped on Atsushi’s shoulder from being carried on the back, as Atsushi and Yosano came through the Agency’s doors. Both of them had went straight to the infirmary, trailing wet from Atsushi’s steps, leaving Tanizaki to wonder just how a shopping trip could take turn into that big of a mess. He didn’t miss how both of Atsushi and Yosano’s clothes were charred and tattered, as if they had gotten into a fight before. Knowing the members’ penchant of attracting trouble, Tanizaki wouldn’t be surprised if that had been the case.

He’s still surprised, however, to learn that the little girl Atsushi had carried in was a member of Port Mafia.

Tanizaki doesn’t have any experience dealing with assassin’s before, especially ones that had turned coat. He thinks about how young she is, how small she had looked, and thinks back to Naomi. If he doesn’t know anything to do with former members of Port Mafia, at least he can deal with younger children.

After all, he has a sister.

He has that in common with Atsushi now, Tanizaki thinks as he waits the water to boil in the electric kettle. It’s late, near-midnight, but Naomi is still studying subjects she should’ve learned in school, were it not for her work as the Agency’s clerk. She gets rather strung-up after trying to solve accounting problems, and the only way soothe her is through a cup of tea. It’s the least he can do for her.

“Tanizaki-san?”

Tanizaki blinks as he turns, meeting Atsushi, all the simplicity of sleepwear, the white of his hair shining under the dorm kitchen’s light. He is squinting at the teabags Tanizaki is holding, before looking up to meet his eyes. There’s no trace of sleepiness found on his face, though his eyes are tired, his shoulders are slumped. Perhaps the tiger’s power extends to curing eyebags and giving Atsushi fresh and youthful face.

“Is that tea?”

Tanizaki can’t help but let a chuckle slip through. “Yes. I’m making it for Naomi, though the water’s not boiled yet.” He smiles at Atsushi, then. “Would you like tea as well, Atsushi-kun?”

There’s a certain tenseness Atsushi adopts to his countenance as he stares—not with apprehension—towards the electric kettle, the teabags. A certain wariness. He is silent when he finally takes out a cup from the cupboard. The electric kettle stops boiling with the sound of a click. Tanizaki hands a teabag over to Atsushi, noting how his hands—not covered by the usual black gloves—shake, just a little. As Atsushi places his teabag in the cup, Tanizaki starts pouring hot water from the kettle.

“How is Kyouka-chan settling?”

It takes a while before Atsushi sighs, then answers. “She’s... fine. We’re getting along... though I was surprised at first, knowing she’s placed with me.”

Tanizaki thinks to Atsushi and Kyouka, how they’ve settled around each other. It’s heart-aching to note that Kyouka’s ease can only return wholly when she’s back at Atsushi’s side. Heart-breaking, to see the sort of fragile gentleness Atsushi first reserves for Kyouka, when his hand settles on her head for a pat. Like he is afraid to hurt her. Or, like he is unused with comforting others, despite how Tanizaki’s noticed that Atsushi longs for it. Both of them are very protective of the other, Atsushi carefully guiding Kyouka under the light, and Kyouka watching Atsushi so no harm would come to him. It reminds Tanizaki, of the bond he has with Naomi.

So, Tanizaki is not surprised, not at all.

“It’s good to hear that, Atsushi-kun.” He pours hot water too into Atsushi’s cup, getting a silent thanks as gratitude. The word warms his chest as he rummages around the cupboard for honey. “You can always go to me or Naomi if you have questions, okay?”

“Um...” once Tanizaki finds the small jar, he dips a spoonful into the tea. When he extends it towards Atsushi—do you want some?—he finds Atsushi, staring at him with uncertainty. “Okay...?”

Tanizaki can feel his smile turn hesitant. Atsushi still takes the honey, though, so now Tanizaki knows he has a sweet tooth. “Since you have a sister now,” he explains.

The jar nearly slips from Atsushi’s grip and Tanizaki’s heart nearly drops out of his chest at the unexpected shock. It’s a good thing Atsushi manages to catch it before it can slip thoroughly. He gives the jar an eye for good measure, before placing it again on the counter to prevent more accidents. Tanizaki agrees.

They both are in a silence where no one knows anything to say.

Eventually, Atsushi registers Tanizaki’s words. His face turns a bit panicked, his eyes wide. “Kyouka is not—“ he stops himself mid-sentence, faltering in the hesitation of his thoughts. Tanizaki smiles as he watches Atsushi, as it finally dawns to him that Kyouka is someone he could call family.

Eventually, Atsushi sighs, amending himself. “I’ve never had one before. Someone to call family.” He looks wide-eyed at the prospect, terrified. But something must've taken over because in a split-second his eyes flash, resolve froming beneath the surface.

Tanizaki leans on the counter, a smile tugging on his lips. He knows what exactly it feels like, to discover having someone to go home for.

“Now you do,” he says. I’m happy for you, he thinks.

In that moment, Atsushi colors red, still holding Tanizaki's gaze. Tanizaki feels his cheeks growing warm as well at the sight, helplessly thinking that it’s a good look on him, on Atsushi, all the light in his beautiful eyes, the white of his bangs falling slightly. Something invisible flutters up Tanizaki’s chest, crawling from his spine. He thinks he can look at Atsushi forever, in this exact same moment.

The moment ends, of course.

Atsushi moves then, a hand raising to his nape, eyes averted away. Tanizaki does the same, sliding his gaze away from Atsushi despite how little he likes it, letting out an exhale through his teeth. He only gets a moment to think what was that, earlier? before Atsushi says, “Um, I should be going back, now.”

Tanizaki lets his whole weight slump against the counter. “Yeah, uh- right.”

He hears Atsushi grabbing his cup from the counter as his eyes fall shut. Tanizaki doesn’t think he can handle seeing Atsushi right now, heartbeat pounding erratically beneath his ribcages. In the middle of his contemplation in using Light Snow as means of cowardly escape, Atsushi suddenly pipes up, “Um, Tanizaki-san?”

“Yes?”

Atsushi is smiling tentatively when Tanizaki turns to him. He still looks tired, but the smile brightening his face says otherwise. “Thanks—for this,” he lifts up his cup. “And for the rest, too.”

Tanizaki feels a grin forming on his face. It matches the warmth forming in his chest.

“You’re welcome.”

Atsushi makes his exit with a small smile that lights up a smoldering fire within Tanizaki, as well as a mumbled out good night. Tanizaki mumbles back to him, lifting up a hand, until Atsushi’s back fades out in the darkness of the hallway, shimmery, like Light Snow. Until he can hear the sound of door knob turning to open, then again to click shut.

Then Tanizaki returns his attention to the tea.

It is oversteeped, he finds, so he drinks it instead of giving it to Naomi. In the middle of its bitterness, the thought of Atsushi crosses his mind once again. He knows that something between them has changed—either for the good or the bad. Tanizaki hopes it's something good, though. He thinks back to Atsushi, smiling tentatively at him, the soft flush on his cheeks. He thinks it can't be bad at all.

Tanizaki smiles.