Chapter 1: Specter
"Pay attention to me, aniki," says a wispy voice from above, shortly followed by the sound of a book clattering to the ground.
Seijuro pays it no mind, gracefully turning another page in his textbook. "Tetsuya, it's late. Don't make too much noise."
A pouty huff echoes through the room and a misty blue figure appears in the far corner, clouded in a mysterious fog. The figure is of a boy, not any younger than Seijuro himself, with soft features and a prominent though half-hearted glare. He folds his semi-transparent arms and stares at the back of Seijuro's head.
As far back as Seijuro could remember, he's had this companion by his side. They often played together as children, and treated one another as siblings. Seijuro hadn't seen anything out of the ordinary with his ghostly brother, but his parents had. They'd been worried as they explained that having an imaginary friend for so long was unhealthy, and that was when he realized his parents couldn't see Tetsuya. He'd felt pretty stupid at the time, not once realizing that they'd never set a dinner plate for him, nor had they ever spoken to or about him.
He'd wanted to scream that Tetsuya wasn't imaginary, but even as a child he knew that would only make the situation worse. So, he pretended to not see Tetsuya while his parents were around. The little ghost had been initially affronted at being blatantly ignored, but eventually he grew used to the routine and only made himself known when they were alone.
When Shiori fell ill, she'd been lying in bed half-conscious when she suddenly gripped Seijuro's arm in a tight vice. With wide and frantic eyes, she'd pointed right toward where Tetsuya was quietly hovering and demanded to know who he was. The ghost had been stunned into silence, and Seijuro introduced him to her. She'd nearly fainted upon hearing his name, and years after her death he still didn't understand what the exchange had meant.
However, he accidentally stumbled across the answer while looking through old family files with his father. Seeing the name 'Tetsuya' written on the documents prompted him to pause and not-suspiciously ask who it was. And, for once, Masaomi didn't ridicule him for asking questions.
Shiori had given birth to twins, the first being Seijuro and the second being Tetsuya. While Seijuro had been born healthy, Tetsuya had not been so fortunate. He had inherited his mother's constitution to an almost exaggerated degree, and hadn't been breathing upon birth. The prolonged oxygen loss sent him into a downward spiral that had him dead within 24 hours. Shiori had grieved the loss so intensely she'd simply refused to acknowledge his existence at all, eventually convincing herself the boy really had never been born.
Even Masaomi seemed shaken up while explaining the situation, and Seijuro for the first time felt some semblance of sympathy toward him.
He decided not to tell him about Tetsuya's ghost.
When he confronted Tetsuya himself about the situation, though, he admitted he'd known the story from the beginning. Seijuro tried his hardest to be mad at him for withholding such information, but he just couldn't. Tetsuya had been there when no one else had been; For Shiori's funeral, for when Masaomi pushed him just a bit too far, and he'd even saved him from his own personality shift. He could never be mad at his brother for all that he'd done for him. Instead he sighed, and quietly requested Tetsuya call him 'aniki'. He was met with enthusiastic agreement.
And now, with the knowledge of their relationship as twins out in the open, Tetsuya's become a lot more outspoken.
"Aniki~ Don't you know because I died as a newborn I'm stuck with the needs of one? I'll die without attention."
"Tetsuya, you are already dead."
"Yes, but...I can still go to the ether. You know, second-death and all that."
Seijuro sighs and puts his pencil down. "If you stop knocking my books off the shelves, I'll come cuddle you."
The ghost perks up almost immediately and Seijuro can't help the fond smile that appears on his face. It seems even incorporeal beings enjoy hugs. Tetsuya settles himself down, and one of his wisps reaches out to place the books he'd already pushed over back where he'd gotten them. Seijuro raises an eyebrow as he settles into bed.
"Have you ever considered that you are basically a ghost cat?"
Tetsuya gives him a considering look and molds the mist over his head into two triangular ears. He stares at Seijuro with wide eyes. "How do I look?"
"Adorable as always. Come on, now, before I remember any more tests I need to study for."
"Aniki is very hardworking," Tetsuya declares as he moves into the invited space next to Seijuro. "His peers seem to be under the impression he's naturally perfect at everything he does, but actually he spends all of his free time studying. He is very admirable, but he shouldn't push himself so hard. It's unhealthy."
Seijuro hums as he straightens the sheets around them, reaching over to turn off his bedside light. "An astute observation, but unless I push myself my grades will slip and you know what would happen next."
Tetsuya sighs, exhaling a cold gust of fog that dissipates into the air. "I wish I could help you more."
"I know you do, but it's not necessary. I have been under worse pressure in the past."
The ghost buries his face into Seijuro's chest. "Not fair. I want to be useful to aniki but because I'm dead I can't do anything."
Seijuro frowns and pulls him away. "Is that what you think? That you are of no use to me?" Tetsuya nods hesitantly and his gaze softens a bit. "Do you really not know? You've already done more for me than anyone else in the world has. It might not be studies or the like, but I would not hesitate to say you are the only one I can put absolutely all of my trust into."
Tetsuya still looks unsure, so he continues.
"Back then, in Teiko, I was so sure everything was going to fall apart around me. I...I said and did some awful things during that time, but no matter how badly I treated you, you always came back. You always called me aniki, and you always threw my stuff around to demand my attention." Tetsuya smiles at that. "You were there for me even when I felt completely alone, and that is the only reason I was able to come back to myself. I can never thank you enough for what you've done. So..." Seijuro looks stern, but his expression wavers as though he's having difficulty keeping his face in check. "Please don't ever feel like you can't do anything for me, because you already have."
Tetsuya looks guilty as he nods, looking away just slightly. The corner of Seijuro's mouth quirks upward.
"Besides that, I should probably give you double the credit since you've done more in your afterlife than most people do in their actual life."
The ghost looks up at him with a grin, the sparkle finally returning to his eyes. "You're right. Do you know how difficult it is to get around without a body? Everything falls right through me if I don't concentrate. I'm like a colander, except instead of holding noodles I just let them all fall into the sink."
Seijuro chuckles. "So, just pouring the pot into the sink with nothing to catch them?"
"Exactly like that."
He laughs, and Tetsuya snuggles further into his body. He's cold and sends electric shocks through his body wherever they meet, but that has never bothered him before. He pulls his younger twin closer and pets his hair, sending wisps of mist straight into his pillow. "I know you don't need to, but do try to sleep. It makes me nervous to see you awake all the time."
Tetsuya's laughter is muffled, and his smile widens.
Suddenly, something occurs to him.
"Hey, why do you suppose it is that I can see you and no one else can?"
A pause. Tetsuya unburies his face with a contemplative look.
"I...never thought about it before. I don't do anything special to show myself to you, you've just always seen me."
Seijuro blinks. "Does that mean I'm a medium?"
Tetsuya stares at him for a moment before snorting. "Are you going to get your own show now where you hire people to act like you're spot-on with your readings? Because you have to look the part if you're going to do that. You know, tacky nails, too much hairspray. The works."
Seijuro wrinkles his nose. "No thank you."
His brother snickers. "Seijuro Caputo."
A pillow hits him in the face, and Tetsuya gasps in mock outrage.
Seijuro rolls over with a childish grin, and allows the tension to seep from his body all at once.
He might be a pain sometimes, but he wouldn't trade his twin for the world.
"Or you could be like Whoopi Goldberg in that movie. Seijuro Goldberg?"
Chapter 2: Phantasm
Surprisingly, it was Aomine who first accepted Tetsuya's existence.
Though he will deny it to his deathbed, he'd been afraid of ghosts his entire life. For this reason, Akashi had been reluctant to introduce them. But Tetsuya had other plans, scaring Aomine after hours in the gym, and after the ghost successfully hit him in the head with a basketball, Aomine declared they were best friends and that was that.
Once again, Akashi was impressed with how simple the brute was.
After that, Aomine made it a point to bring a Ouija board or the like with him in order to communicate with his new ghost friend. Before using it he always warned Tetsuya not to bring along any of his own ghost friends, to which he retorted his friends didn't want to meet him. This always resulted in a childish argument between Aomine and a seemingly invisible being that cemented the idea of him being certifiably insane in the minds of his peers.
Then came the fateful question.
"Sooo, Tetsu..." Aomine drawled. "Can you like, possess people and stuff?"
Tetsuya guided the planchette to spell out 'never tried it'. Aomine raised an eyebrow.
"Really? Why not?"
'Didn't have a test subject.'
"Test subject, huh...I guess it would be weird to use your brother as a guinea pig, huh. Plus I bet there's lots of weird stuff going on in that freaky brain of his." Aomine tapped on the planchette with a considering look. "Ya know, I'm well-known for my stupid decision-making abilities. Wanna use me as your test subject?"
Tetsuya stared at him with wide and somewhat apprehensive eyes. He only wished Aomine could see it so he could maybe understand how ridiculous he sounded.
'Are you crazy?'
Aomine snorted. "You're asking me that when you live with Akashi Seijuro? You've got some weird standards, Tetsu."
The ghost rolled his eyes and sent a chilling mist in Aomine's direction. He shivered with an indignant glare.
"Alright, alright, yeesh! Calm down with the ice!" He huffed. "Look, I'm sure it can't be that bad. Plus it would be pretty cool, yeah? Why not try it just this once while someone is willing?"
Tetsuya sighed. 'One time, that's all.'
"Yes! This is gonna be awesome."
'Aomine-kun, I'm not sure what to do here.'
"Huh. Makes sense if you've never done it before. Maybe you just kinda need to...sink in or something?"
Tetsuya shrugged without a response. He stared at his companion, concentrating to visualize his life force. It was a fierce, blazing blue, and he squinted at its brightness. Aomine's aura was jagged and angry around the edges, but smooth and gentle in the middle. Tetsuya grinned in amusement-auras never lie. Aomine's rough on the inside and sweet on the inside, there's no longer any doubt in his mind.
Tendrils of mist reached out to him, and he quietly reached forward into the angular blue waves until-
He lets out a ghostly shriek and recoils. He turns toward the door, prepared for a reprimand at the hands of his brother.
"What are you doing?" Seijuro sounds and looks genuinely confused. "And moreover, where is Tetsuya?"
Tetsuya blinks and his face morphs into one of annoyance. How dare his brother feign ignorance in his presence! He raises a hand to lecture him when he notices something peculiar.
His arm is much, much heavier than it had been before. He slowly looks down to his outstretched hand...
...and immediately launches himself to his feet with a scream.
Seijuro looks positively scandalized as 'Aomine' rubs his hands all over his body, making assertive noises every few seconds. He frowns and crosses his arms.
"Aomine, I know you have a thing for yourself, but please refrain from self pleasure in my presence."
'Aomine' pauses and turns toward Seijuro with comically wide eyes. He points at him with his mouth wide open.
If Seijuro looked scandalized before, he looks absolutely mortified now. An extremely uncharacteristic look of horror crosses his face and Tetsuya has to stop himself from laughing. Despite his best efforts a couple snickers escape as he tries desperately to compose himself.
"Um...ahem," 'Aomine' coughs. "Sorry about that. Uhh...would you believe me if I told you I was possessed?"
Seijuro's eyebrow twitches. "No."
Somewhere in the back of their mind, Aomine screams at him not to make the situation even worse than it is. He blocks him out and continues digging his metaphorical and possibly physical grave. "Well, that's the truth. I've been possessed by the devil and he's telling me to call you aniki."
Seijuro's face goes blank and Tetsuya breaks into thought-based hysterics. Aomine lets out a dull screech deep inside their shared mind and his laughing grows even louder. He wheezes and makes Aomine pose dramatically.
"So, big brother Akashi, will you accept this devil's form of mine?"
Before Seijuro can reply properly, 'Aomine' crumples to the floor in a dull and painful-looking heap. The elder Akashi stares at it with half confusion, half satisfaction, and the younger suddenly manifests directly above Aomine's fallen body, still in the dramatic pose from before. He blinks awkwardly and slowly moves his limbs into a neutral position while Seijuro stares at him in disbelief.
"Tetsu...ya?" He blinks. "That...what..."
Tetsuya stares back at him in wonder. He's never seen his brother wearing such a face, so he commits every last feature to memory while Aomine stirs beside him.
"You...stupid ghost...bastard..." Aomine wheezes. Tetsuya looks down at him with an innocent face. "Gonna...kill your dead ass again..."
"You volunteered, Aomine-kun. You cannot fault me for this."
"Bull...shit! I didn't think you'd...fuckin'...do this shit to me! What the hell!"
"You should have known better, really."
"Oh, would you just-!"
"Wait, wait, wait a moment," Seijuro interrupts, hands up. "You guys are talking to each other."
Aomine pulls himself up into a seated position and grumbles. "Yeah, of course we are, we're..."
Realization hits him, and he sharply turns to where Tetsuya hovers next to him. The ghost waves at him, and he hesitantly waves back. He looks to Seijuro, who appears just as confused as he is. He's not sure if this makes him feel better or worse, but he's definitely feeling something.
"It would seem," Tetsuya begins. "That possession has made it possible for Aomine-kun to see and hear me."
"So, you..." Seijuro's eye twitches rapidly and Tetsuya vaguely wonders if it's unhealthy. "He volunteered to be possessed by you...and now that you are separated, he can see you." Tetsuya nods and he brings his hands up to bury his face in them. "I was not even aware you were capable of possession."
His younger twin shrugs. "Neither was I. But I guess I am. Pretty neat, huh?"
"Neat, my ass..." Aomine huffs through clenched teeth. "If you were alive I would throttle you for that."
"No, you wouldn't."
He sighs. "Yeah, you're right."
Seijuro takes a deep breath and suddenly it's as if his composure was never broken at all. Tetsuya feels a little jealous. "Alright. I cannot fault Aomine personally because he was not in charge of his body, but I will be delivering a letter to his coach to give him extra laps for disturbing me."
"Hey! Damn it Tetsu way to ruin my life!"
"Don't blame him, you volunteered." Aomine slumps down and he continues. "As for you, Tetsuya...no more possession without my permission."
Tetsuya huffs out a puff of transparent smoke and crosses his arms. Aomine mutters something about unfair favoritism.
Seijuro continues to lecture them about the dangers of unknown territory, and Tetsuya allows his mind to wander. If he could do that to Aomine so easily, who's to say he couldn't do it to someone else? A plan starts to take shape. If he could possess every single one of his brother's old teammates, certain chaos would ensue, and since his twin has such a soft spot for him he'd never be truly punished, he wouldn't have to deal with anything more than a lecture afterward.
Granted, the amount of time he'd been able to hold Aomine's form was not very long, but with some good practice he's sure he could cause some serious trouble.
A grin spreads across his face. It's only a matter of who to take over next...
"Tetsuya, are you listening?"
"Ah? Oh! Yes, sorry, I just spaced out...you know, ghost attention span..."
"That isn't a thing and you know it."
"Don't be phantasm-ist."
"That...that's not a word..."
"It ought to be."
Aomine suddenly wishes he lived in another plane of existence.