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Saving the World with the Power of Physics

Summary:

How does one travel back to a world where travel through space, time and dimension was barely concept? Kakashi has a feeling it's due to his Mangekyou, but this world he's in has yet to awaken Kamui.

Perhaps physics was the only explanation available in this time.

Originally titled The Physics Behind How Kakashi Saved the World

Notes:

(See the end of the work for notes.)

Chapter 1: Displacement

Summary:

displacement

/dɪsˈpleɪsm(ə)nt/

noun
1. the action of moving something from its place or position.

Chapter Text

Waking up in a body smaller than your own is an experience Kakashi doesn’t want to experience again. His small soft hands pat around this foreign body, adjusting to the way his skin remains unblemished from future scars. He traces over the scar that haunts his eye, and opens it, revealing a world he left behind a few decades ago.

He gets comfortable in this body and lifts himself off the bed, and is very underwhelmed by the world at such a short height. He muses at the thought of his cute little genin, and wonders how much taller he would be compared to them at the same age. He rids himself of his musings and strides through the Hatake compound in search of a calendar he knows to be lying around.

 

He almost arrives late by habit and inwardly curses his best friend for being such a bad influence. Either way he arrives on time to the training grounds and hopes that it doesn’t warrant Minato-sensei’s suspicions yet.

He greets Rin with enough enthusiasm as appropriate for his supposed angst, and nods to the blond man who smiles a gentle smile, but not unlike his son to come.

He looks away before he imagines the whiskers on his face, and instead focuses his attention on his other teammate.

He spends the afternoon trying not to call them by the names of Team 7 of the future- the new Legendary Sannins. He averts his gaze from the past future and dwells his attention on the current past.

It’s a difficult feat to manage when he knows the potential this team had; if he hadn’t screwed them over.

 

Minato notices that his lonely student engages with his teammates with a familiarity from experiences he hasn’t witnessed. He smiles at this exchange before catching onto the wistful gaze he held with the boy, before he turned away.

(He worries, but he knows the boy will not react well to his concern, and instead files this for a later conversation.)

 

Kakashi thinks that his mission in the past is going well so far. He stares at the summoning scroll in his hand, hoping against all odds that the seal his student developed for him would work regardless of all space and time. He’s spent a month or so in this new world training his chakra reserves, expanding it in order to support this quest.

(And he knows it works. He’s here after all.)

He signs the contract and reunites with his beloved ninken, all so small but full of the future’s wisdom. They greet him warmly promptly before dogpiling onto him. He laughs such a bright laugh that no one would believe it to be the Kakashi Hatake, and falls on his back, exhausted from the big chakra withdrawn from summoning his pack.

He misses this. He missed them.

(He thinks that maybe going to the past is a mistake, and that he’s going fuck up this future too. Pakkun would like him to think otherwise, after all, he’s not alone in this anymore.)

That night, he sleeps surrounded by his beloved ninken, who at this point in time are just dogs- puppies. It’s quite an endearing sight, one that Kakashi wouldn’t mind staying in forever.

(‘But his students,’ he thinks, and he remembers his mission, and all the hardships he’s accepted for this mission.

He remembers himself.)

 

They meet again under the trees of the same training ground. The shade helps him cool off from Minato’s spar, and he inwardly curses himself for having such a massive growth spurt.

Whatever, he still has another month to get his rhythm back.

Minato-sensei calls everyone over and pairs Obito off with Kakashi while he takes Rin to the side to observe. Obito stands on the other side of the field, and Kakashi remains rooted in this present, trying to separate the image of a taller, much harsher Obito in his Madara garb.

They take off at the signal, and with Kakashi’s smaller form, he quickly vanishes to the trees almost unseen to even Minato himself. He decides on a battle strategy easily befitting the Kakashi of the past, and quickly makes a shadow clone standing near the edge of where the trees meet the field.

“Coward Bakashi!” Obito shouts. “How dare you run from me!”

The shadow clone leaps from its confines in the shadows.

 

Minato-sensei takes them out to eat later that week. Kakashi suspects that it’s something to do with his change in behaviour and morals, but he plays his detached role quite well. It’s not like there’s much to do to sell his act- just brood about the future and ignore whatever Obito’s saying, even though it weighs heavy on his heart every time he has to acknowledge the ghosts of his pack, both past and present.

Minato raises a brow, but doesn’t comment, and instead lifts up the flap and ushers them into Ichiraku’s. He takes a seat inside the booth and inhales the scent of fresh ramen and general peace.

It’s the little things that make him realise what he’s missing out on.

They order modestly (or whatever Obito calls modest, the boy holds no bounds) and spark up idle chatter about their missions and training in general. It’s Obito who stirs the conversation to Kakashi’s behaviour, and honestly he saw this coming.

(He thinks of a knucklehead ninja, his successor and the world’s saviour. They’re too alike.)

He merely smiles, an action so unlike the Kakashi they know so well, yet it was the only thing he could do.

“I got lost on the road of life.” He says. “But now I’m back.”