Written for the Kakairu Mini Bingo 2019, for the “Sensory Depression” prompt. A Stranger Things fusion.
Many thanks to @LadySmaell 
Kakashi was adrift.
He knew where he was, what he was in: a tube made of cold metal, with a hatch that could only be opened from outside. Yet his body would not recognise his upright figure held buoyant within, the perfluorocarbon fluid filling his lungs where air should have been; the boundaries of the tube from the darkness surrounding him.
For all of his calmness, his rationality, his memories of being forced feet first into the tank and plunging into a liquid heavier than air but breathable all the same, Kakashi’s body was convinced it was adrift in a boundless, empty darkness where no one could be found.
But there was someone and some things that could be found. Why else would they put him and the rest of the lot into the tubes, if not to reach out and to visualise? It was not an exercise foreign to Kakashi, having done so, so many times over: a locked office as good as unlocked, a document confidential and otherwise inaccessible spread open for his perusal.
The location of a man fleeing for his life, despite his otherwise meticulously planned escape route. As he was dragged back to this very facility, to ensure his mouth remained shut.
Kakashi could do it again, here and now. It was what they wanted him to do, after all. He could reach out - he could think of, could want, could yearn - and surely, surely, he’d be there. A flash of hair, brown in the brilliant sunlight, a wide smile -
The slightest of pressure across his throat. A reminder.
“Hound.” The voice echoed, reverberating into the darkness and unto itself. “Your mission."
Slowly, reluctantly, Kakashi nodded. The pressure lifted, but the collar remained - a heavy presence that he had once been free of.
He reached out into the darkness, not for that person, but for something else. The tower, they wanted the tower: white against the brilliant azure sky. The tower, with its offices both public and private; the tower, where Iruka also -
The band tightened yet again, more harshly. Kakashi coughed, the foreign heaviness of liquid squeezed out of his lungs - and seeping back into it with a sharp intake of breath.
Message received. He pulled himself away from thoughts of Iruka’s desk, that desk cluttered with documents and knickknacks. A mug declaring him the best father, a clay figure made by clumsy hands that attempted valiantly to look like a dolphin. A desk indistinguishable from the sea of a hundred other desks, a multitude of other workers who might have been more important than Iruka.
(But not to Kakashi.)
Instead, he thought of hallways and corridors, walls shimmering into watery existence before him like reflections upon the surface of a lake. Thought his way up towards the fifth floor of the tower, and meandered his way past empty rooms and blurry windows.
Up into the mayor’s office, past locked doors and alert guards, and into a meeting Shimura Danzo would have never been privy to, if not for Kakashi.
Within the room, Sarutobi Hiruzen sat. His image wavered like ripples cast by a stone across a pond; his voice crackled like static as he spoke. His voice would be repeated outside, emanating from a speaker, for the benefit of the men who pushed him into this very tube.
“Thank you for bringing this issue to my attention,” Sarutobi was saying to the other person within the room. The figure remained blurry, despite Kakashi’s best attempts - interspersed with static and distortion, stripes of shifting colours splashing and stretching thin across the figure. Sarutobi, the paranoid bastard, had probably built the walls of the tower with something that could keep psionic intent out.
Even so, he couldn’t keep Kakashi out entirely. Something Danzo was surely grudgingly pleased about. It had likely rankled, that the various agents that were loyal to him were unable to penetrate through Sarutobi’s defences - that he has to depend on Kakashi to pierce through.
Still, Kakashi was here now. Despite his escape, despite his powers - Kakashi was here doing Danzo’s bidding.
He dragged his attention back to the scene before him.
“It seems as though more has been going on under my nose than I had known,” Sarutobi sighed. World-weary and old; Iruka had talked about him as though he were a father figure, a mentor and Kakashi could see why Iruka considered him so. He wondered if he had allowed Iruka to bring him here, to this very room like he wanted to from the first day - would things have been different? “I had thought… no matter. There is only looking forward.”
That much was true. Kakashi breathed out, the rush of liquid cool against his teeth. He had all the time to regret when they shot him full of tranquilizers and brought him in.
Then the other figure said, “Hiruzen-sama.”
Their voice sliced past the static and feedback of the void, clear as a clarion’s call. Kakashi jerked and turned to look at them - turned to look at Iruka, seated on the chaise.
Irony that Root wouldn’t let him reach out for Iruka, in the hopes of making Kakashi languish in worry over whether Iruka was in their grasps - a hostage for Kakashi to surrender all his concessions. Kakashi had known that Iruka was safe, yet there was always the thought that perhaps he had failed. Perhaps Iruka had been smarter than he should have been. Perhaps.
Yet here Iruka sat before him now, in the safest place he could be. Kakashi took in all the details he could: Iruka’s ponytail tied more messily than usual, the clothes he must have slept in, the hoarse cadence of his voice.
There was a flurry of activity outside of the tube, but Kakashi could not find it in himself to care, not with Iruka formed in crystal clear clarity before him, as though he was in the tube with Kakashi himself. Not with his eyes: bright and piercing and still so very alive.
“About Kakashi,” he was saying. There was the distant sound of a lightbulb whining and shattering as it shorted out - as Kakashi processed his own ineffable joy, his uplifting relief. Iruka got out, Iruka was safe; Iruka remembered him even though Kakashi locked him in a basement to spare him from Root’s agents. “Please, Hiruzen-sama - “
“Iruka,” the old man said, but Iruka barrelled on, much like how he did when Kakashi threatened to use his powers against him, how he pushed him away the first few days of their acquaintance.
“He wants to leave,” Iruka said, earnest and sincere. His voice echoed within the tube, outside of the tube, words overlapping in close canon. “He needs to leave, he didn’t - doesn’t want to be there anymore -“
Yes, yes - that was all Kakashi could think - I want to leave this darkness and hold you in the sunlight, I want to walk you to that desk and walk you home, I want -
There was a building cacophony in the background, of shouts to drain the tube, to stop, to disconnect - but Kakashi was damned if he’d let go so easily now that Iruka was in front of him by sheer happenstance.
He raised his hands towards the gentle line of where Iruka’s jaw should be, desperate for a single touch. The bar slammed heavy against his throat - he choked - but his hand remained outstretched, raised. Forward, forward - until his palm came to rest gently against Iruka’s cheek.
Kakashi would never know if the warmth beneath his skin was of his own imagining - or if his yearning was so strong as to connect to Iruka through the void.
It would have been enough - it was enough - but Iruka’s own hand raised, touching the spot where Kakashi’s hand was, involuntary; it brushed against Kakashi’s own.
Against all odds, he raised his head. Turned away from Sarutobi to where Kakashi hovered, in that room he was not in. And he asked, breathlessly vulnerable and hopeful, “Kakashi?”
The heart seized with hope is like a rope pulled taut. Kakashi could only press his hand more firmly against Iruka’s face, cupping it so. The shouts were louder, the bar about to asphyxiate him - but there was only the two of them in that void. Only that mattered.
Iruka’s eyes widened, then set in determination - the same determination he faced Mizuki down with before he even knew Kakashi was there to protect him.
“We’re coming,” he said fiercely. “We’re coming, we’ll find you - wait for me - “
Gladly, Kakashi said, because he would wait for Iruka even if the corruption from the other side spread slick across the portal and into their own realm, and after that. If he couldn’t go to him, he would wait - he would -
He kept his eyes on Iruka even as the hatch opened and bathed the other in a ray of fluorescent light, drowning his image out from Kakashi’s sight. As he was dragged, wet and gasping, out of the tube, and thrown in front of Danzo, vomiting clear fluid as his body desperately took in air.
Danzo looked impassively down at him. Kakashi bared his teeth in a mirthless grin in reply. Iruka knew - that meant Sarutobi knew, and Sarutobi would act.
There was little time left for Root to act. The twist of Danzo’s lips told Kakashi that he knew so.
“I think that you might just be expendable after all, Hound,” he said softly. “Prep him for crossing.”
The thought of being sent over to the corrupted universe would have been a threat, once - but Iruka was coming. Kakashi would wait.
They would make it out fine.
Is there more?
I think you did a really great job with this prompt!