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Shape of the Soul

Summary:

What happens when you shred two souls, stick the pieces together, and stuff them into an already occupied body? A lot of stress, that's what. Stress isn't enough to stop Sukuna though, not when there's a plot to shred to bits.

Or, author acquired SI!Kuna brain worms to the point of publishing their first fanfic. Be patient with me please.

Notes:

(See the end of the work for notes.)

Chapter 1: Chapter 1: random bullshit go (SI!kuna has a really bad day)

Notes:

(See the end of the chapter for notes.)

Chapter Text

Cold, slimy, and loud. Those were the first things they registered the moment of their wake- and what an unpleasant way to wake up. An instructive swipe of the fingers, a wave of energy (energy? What energy) and the sensations went away. They blink.

 

A school rooftop- empty, save for one presence and the smell of blood. Pale moonlight pours over the scene. They blink again- the moon shines above, full and clearer than they’ve ever seen it. Or is this how it has always been?

 

They turn to the presence, and see a dark-haired teenager, staring back at them with wide and fearful eyes. Familiar eyes? Fushiguro Megumi, their mind supplies, and something sets into place like a puzzle piece.

 

They lift their hand up, examining the sharp nails and dark tattoos, and with a surreal sort of clarity, they think: I am Ryoumen Sukuna. It's both a dawning, horrifying revelation, and something so obvious it settles in their bones like fact. They know they are Ryoumen Sukuna, somehow.

 

…An unpleasant way to wake up, indeed, they think.

 

They turn to the bleeding Megumi and take a single step (to which the boy reels back like a startled animal). Before they can do anything else, a tug comes from deep within themselves.

 

“Hey! What are you doing with my body!” A voice in their throat says, and it's not their own. The same clawed hand reaches up to grab their throat. Surreal, for more than one reason.

 

“You are the owner of this body.” They respond with the same throat, yet the sound that comes out is much deeper, rumbling within their lungs like a growl. They bite their tongue to suppress the disbelieving laughter that threatens to bubble out of their throat. “Interesting. Would you be willing to lend me your vessel for a moment?”

 

“Huh? Lend you? You took it!” Yuuji shouts, the indignation clear in both his voice and the brush of fiery emotion on the edge of Sukuna’s mind. Unafraid, even as his body is puppeteer by something unknown to him. As brave as they remember him being, they think with something akin to joy.

 

“I did not ‘take’ anything, host, you invited me in. Which is why I am requesting you lend it to me for a moment longer so I can fix the boy.” Sukuna drawls, slow and patient.

 

Megumi blinks owlishly at them, and they swallow down more laughter.

 

“Uh?” There's a tense silence. Yuuji’s confusion and hesitance bleeds through into Sukuna's mind. “ …I guess I can do that? Thanks, creepy guy!”

 

At this, they actually snort, even as they bend down to use Reversed Cursed Technique (which they remember, which they can use?). Megumi, surprisingly, holds still even as he eyes them like a rabbit plotting its escape route. Like summoner, like summoned, Sukuna muses.

 

He doesn't need to escape, though he wouldn't know that. Sukuna has no desire to hurt him, and it takes barely a moment to close his wounds. It comes so easily, as if they have done it a thousand times before. (A memory of stitching together their own muscle fiber flickers by, unwanted.)

 

They stand back up and take a few, slow steps backwards, making distance between them and the little summoner.

 

“Thank you, host.” Sukuna performs a bow before they feel a wash of numbness over them. Their control of the body slips away like a fading dream, and for a moment they feel nothing.

 

“Woah, that felt weird!” They hear Yuuji’s voice, and then they open their eyes within a pool of blood. Their inmate domain, as they remember- somehow.

 

Sukuna turns and wades through the blood to their shrine, letting the sound of the dialogue they’ve already heard fade into the background for a moment. They rise up the steps, one stone step at a time. The blood laps at the edges like seawater, and distantly, Sukuna wonders why it does that when there's no moon in the domain.

 

“...what the fuck.” They mutter (in English, because both modern and Heian era Japanese don't have the same impact). “What the fuck. What the actual fuck.”

 

They collapse onto the stone floor of the steps, looking up into the deep red night of their domain’s sky from their new view on their back. A slightly hysterical chuckle slips out- the only thing that stops them from breaking into full-blown laughter is the adrenaline and the knowledge they will be called upon in a minute or two.

 

Thank God they work well under pressure. Or under severe disorientation from waking up with two sets of memories (not now, don't think about it now, it's not time yet), one of the two.

 

They pinch their cheek, and are unsurprised when it hurts. It would be so much easier if this was a dream, but no dream they’ve ever had had ever been this vivid or detailed. They’ve had some strange dreams before, but they’ve never had a dream where they could feel their own emotions and memories chafe against each other, unfamiliarity and familiarity bleeding together all at once.

 

Breathe in, hold, breathe out. They bite their tongue and ground themselves with the pain. The pressure of their palms on their (four) eyes soothes them a little more. They're confused and definitely scared, but those feelings won't help them right now. Not when there's work to do.

 

“...I don't know myself right now, but I know what I need to do.” They whisper, and it feels right. “I don't know what’s happened, but I can figure it out. Okay. Okay. I can do this.”

 

They force themselves up. “Okay. What do I need to do? I need to…prevent the plot, obviously. But right now, I need too…hm. Get through this interaction, first of all. I’ll have ten seconds minimum, unless I negotiate for increased time. I could act like the canon Sukuna, but would that work in my favor?”

 

Their claws produce a satisfying tap on the stone steps, which is suitable percussion to accompany their thoughts. “To carry out my goal, I need to gain the trust of sorcerers. So, convincing Gojo to not kill us is a good start. And…preserving the plot would be good, but that's not feasible if I don't want to be a dick like canon Sukuna. This is my chance to set a different first impression- not that it would change much, but still. How do I play this?”

 

“Uh, creepy guy? Are you there?” Yuuji’s voice suddenly echoes out, and Sukuna bites down a curse. They are out of time.

 

“I'm here, host. Is there something you require of me?” They say, imperious as the Sukuna of their memories is. The act slips on so naturally it feels more like welcoming an old friend, and they file that thought for later analysis.

 

“There's someone who wants to talk to you? Can we switch out for a second?” They feel a press of intent on their soul, akin to a nudge forward.

 

“Hoh? Someone wishes to speak with me? Very well, host. I’ll humor them for, let's see…one minute.” They feel a flutter of surprise from Yuuji.

 

“Oh, thanks! Uh, Sukuna says they’ll give you one minute.” Yuuji repeats to his audience, and is met with odd looks.

 

“Wow, one whole minute? I'm honored!” Gojo smiles in the obnoxious way Sukuna remembers seeing on screen so many times before. It is an even stranger sight in person. “Can you handle that, Yuuji-kun?”

 

“I think so!”

 

Sukuna experiences the soul version of vertigo as they are yanked back into reality.

 

They click their tongue as they steady themselves on the rooftop, narrowing their eyes at the sight in front of them. White hair that sticks up like a paintbrush, dark clothes and matching blindfold- there stands Gojo Satoru, the strongest of the generation.

 

“Wow, it's nice of you to grace us with your presence, your majesty~” Gojo chirps, and if Sukuna didn't know what they did they would mistake it for being carefree. But they do know better, because they know this man. Or, of him at least.

 

Time to improvise, I guess, Sukuna thinks. “Sorcerer. Don't bother with such titles if you have no intention of respecting them.” They tuck their hands in their pockets, taking care to not tear the yellow fabric with their claws. It's a very comfy hoodie, and Sukuna finds themself incredulous at canon Sukuna's lack of taste.

 

Gojo keeps smiling at them, and their form is too relaxed for a fight. It reads as arrogance to Sukuna's four eyes (which, they realize, is because they know exactly what someone looks like when preparing for a fight. Another thought to shelve for later). Gojo believes Sukuna can't hurt him, and their memories of canon prove him correct.

 

Sukuna maintains eye contact as Gojo’s smile widens. “What, you're not going to do anything? Not even a little bloodshed? Doesn't the King of Curses want to take his new vessel out for a spin~?”

 

Sukuna rolls their eyes. “No. This vessel is too weak, and I possess only a fraction of my power. There are better ways to spend my time.”

 

Gojo tilts his head as he stares down Sukuna- which is far more uncanny when you can't see his eyes, Sukuna notes.

 

“Really? I didn't expect Ryoumen Sukuna to be such a coward! Does it come with old age, old man? Or did you lose your fighting spirit when you incarnated?”

 

Sukuna chokes out a laugh, because while Gojo is clearly trying to rouse him up, he is closer to the truth than he believes. “So what? Would it not be convenient to you if I did?”

 

The statement clearly startles both Gojo and the younger sorcerer, who both twitch like Sukuna had yelled. Belatedly, it occurs to Sukuna that any admission of weakness would be out of character for the infamously arrogant canon version. They swear within their mind.

 

They choose to power forward anyway. “I am aware of your desire to test the boy’s control over me. As you suspect, I cannot ‘enact bloodshed’ when he will seize this body back the moment I try. I would prefer to observe. And observe I will do, for there is so much to learn in this new era.”

 

Sukuna narrows their eyes. “Is this all you desire from me, Sorcerer, or do you wish to waste both your and my time even more?”

 

Gojo holds up his hands, counting down on his fingers- 5 seconds left. “I don't know about you, but I haven't wasted my time at all! See you on the flip side, your majesty- oh, and thanks for healing my student!”

 

Sukuna lets himself groan with annoyance before the numbness returns, and in a blink they are back on the stone steps.

 

They pinch the bridge of their nose as the input from Yuuji’s senses abruptly cuts out- Gojo has knocked him out, judging by the sudden lack of activity from Yuuji’s soul.

 

Sukuna feels a wave of exhaustion hit them. That could have gone better, but it could have gone much worse as well- at least they managed to avoid Yuuji getting hurt. They could still use a nap, though.

Notes:

Sukuna's no-good-very-bad brain scramble transmigration adventure. Wish them luck, they're going to need it.

Anyways, welcome to my first fanfic! I've read way to may SI!kuna fanfics and I need to get the SI!kuna brain worms out before they eat my soul. Tell me what you think, and please be nice, I'm very nervous. Have a good day!