Disclaimer: Naruto does not in any way belong to me, it's the property of Kishimoto, etc. Likewise, KHR! does not in any way belong to me, it's the property of Amano, etc.

Learning Curve

02.

Kakashi ends up staying awake for the rest of the night, despite numerous assurances by Tsuna that he can sleep if he'd like. Even though he tells himself that he wouldn't stand a chance against Reborn and Tsuna if they really wanted to kill him, his instincts simply won't let him fall asleep under these circumstances.

Tsuna provides him with bandages to wrap the wound, which Kakashi does with an ease born of years of self-administered field dressings. Then he does Obito's, despite knowing that his former comrade would probably kick him in the face rather than thank him for any kindness.

Reborn situates himself in a hammock in the corner of Tsuna's room, while the teenager in question climbs into the only bed and immediately drops off to sleep.

What a strange pair. Kakashi's eyes linger on Tsuna's sleeping form, until Reborn, rather pointedly, pulls out one of the black weapons again.

Kakashi decides to study everything but the bed and its occupant after that. No reason to unnecessarily distress the uncanny child...

Reborn can't be more than five or six - Kakashi supposes it isn't that unusual that a child of his age should already seem so hardened. Kakashi himself was already a full-fledged shinobi at that age, after all. But on the other hand, Kakashi is far from the norm.

There's a yellow pacifier hanging around Reborn's neck, though - it seems strange that someone so mature would have such an object on their person. Pacifiers usually get put away after infancy, and while Reborn might be young, he's no infant.

"Questions, Hatake?" the child asks.

On second thought, it sounds more like a dare. "Ah, just thinking, Reborn-san," he replies politely.

Reborn snorts. "I may not be an ordinary child, but you're not what you seem to be, either," he states. It's more than a little unnerving how intense that stare is. "You act far more mature for your age than you should."

"I take it you and Tsuna-san are not the norm, then..?"

"Correct," Reborn says, dry as bone.

Such a succinct reply doesn't really tell Kakashi anything, beyond confirming something that was already fairly obvious. "The circumstances seem a bit different between the two of you, however..." Kakashi fishes.

Reborn snorts again. "To put it mildly. Why don't you acquaint me with your 'circumstances', and then I'll consider telling you something about Tsuna and me?"

Reborn is very obviously not a child. It should have been relatively easy for Kakashi to manipulate a kid into telling him pretty much anything he could think to ask, but Reborn is very much aware of who holds the power in their duo, and it isn't Kakashi. "So generous, Reborn-san," Kakashi says, smiling. "I'm not exactly certain of the circumstances myself - and things seem to work differently, here. I shall endeavour to explain things to the best of my ability, however..."

"By all means, endeavour," Reborn replies, unperturbed.

"In our dimension, Obito and I are-"

"-Obito?" Reborn interrupts, frowning now.

Kakashi glances at Obito's prone form. "He has used the alias of Madara for- for many years. But I first knew him as Obito." Kakashi attempts another smile, but it comes out as a grimace. At least he still has the face mask to hide the majority of his face, even if he is inexplicably missing the Inu mask. "We were comrades, once."

Reborn digests this information, then motions for Kakashi to continue with the tale.

"As I was saying, in our dimension, Obito and I are both adults-"

"-how much older?" Reborn interrupts again.

"Early thirties," Kakashi answers. "I don't know why we seem to be in our late teens now.

"Obito and I are the only people - that I know of - who can use a technique called Kamui. It allows us to transport objects or people to a dimension that is only accessible to the two of us - it's also called Kamui, as far as I know. Maybe Obito has another name for it. I've never been to the dimension myself, but I know that Obito has... and he's confirmed that this is not Kamui, so... Perhaps it's because we used the technique on each other simultaneously that we arrived here in... Namimori?" Kakashi shrugs; it's the only explanation he can think of, but it doesn't make much sense either.

"Hm. Given your reactions earlier, Flames of the Sky - or of the Earth - are not the primary source of energy or power in your dimension, are they?" Reborn questions.

"That's correct. We use an energy known as chakra... Everyone has it in some form, but generally those with chakra stores significant enough to use are shinobi. There are seven general elements that chakra can be molded into-"

"-seven?" Reborn interrupts. Kakashi's sensing a theme, here. "Name them."

"Fire, Water, Earth, Lightning, Wind, Yin and Yang chakra," Kakashi rattles off dutifully. "I honestly don't understand how there can be Flames of Lightning, but in the other dimension my chakra affinity was lightning, so that could explain why..."

"There are seven - well, eight - but originally there were seven Flames of the Sky," Reborn explains. "The Sky, which governs over all. It is the rarest form of Flame, and generally mafia bosses have this attribute, as in Tsuna's case. The other six are Storm, Sun, Lightning, Rain, Mist and Cloud."

"The system is based on weather..?" Kakashi frowns thoughtfully. It doesn't really make any sense to him, but he files the information away anyway. Knowing how this dimension works can only be beneficial in the long run. "And what's the eighth type that you mentioned?"

"Ah, Flames of the Night. I suppose it can be considered an even more rare form of Flame than the Sky, but before this it was limited to a select group of individuals..." Reborn looks from him to Obito's still-unconscious form. "Though as you have yet to use it since bringing yourselves here, perhaps it will remain that way."

Kakashi shrugs. "I don't know if we can. The technique was tied to a genetic trait known as the Sharingan."

"Your eyes," Reborn says. "... I noticed that your former comrade is missing one. Did you take your left eye from him, Kakashi-kun..?" It's a pleasant inquiry, like they are (still) discussing the weather.

Kakashi doesn't quite stop the flinch. He has been regretting a great many things for a very long time. "No. You're not wrong, this eye was originally Obito's... but there was a- an accident. I made a foolish decision, and Obito paid the price. He gave me this eye." And Kakashi made a promise in return.

"This occurred before he assumed the alias of 'Madara', I imagine."

"Yes. I thought he was dead. It turns out he wasn't." The alternative was so much worse.

"In the meantime, events transpired to pit the two of you against each other," Reborn surmises.

To put it mildly. "Yes."

Reborn stares at him, and Kakashi meets his gaze evenly.

"That technique - Kamui, was it? Try it now," Reborn orders abruptly.

"... I'd have to send something away, to the other dimension. That's how it always worked in the other dimension. I mean, the original one." Kakashi sighs, fully aware of how this must sound.

There are two too many dimensions for him to keep track of, now, and he's hardly in a state to try to discuss them. The overload of information is almost too much for him to take in. With Obito being revealed as (one of?) the mastermind(s?) behind the Akatsuki, their arrival in Namimori and everything that Reborn has generously told him about the place foremost in his mind, Kakashi barely has any attention to devote to trying to explain a technique that he doesn't fully understand to someone who has barely any frame of reference for it.

Reborn just looks amused by Kakashi's fumbling. He points at the desk beneath the window. "Send that lamp away, then. To Kamui, that's what you call it, isn't it."

Kakashi nods, glancing at the object in question. Perhaps, like his Flames of Lightning, the technique will just come to him.

It doesn't, though. Nothing happens.

"How disappointing," Reborn says, after a few moments. He doesn't sound disappointed or pleased either way, though. "Well, you'd better get to sleep."

"Likewise, Reborn-san," Kakashi says mildly, uncertain whether or not he should be disappointed that Kamui - or its Flame equivalent - doesn't seem to work here. It means that he and Obito probably can't return to the shinobi dimension, but perhaps that's for the best. As long as Obito's here, he can't complete his plan. "It's important for young children to get a full night's sleep, is it not?"

"I could say the same about annoying teenagers," the child returns, though he's settling himself quite comfortably in hammock as he says it.

Kakashi leans his head against the wall, but now that Reborn seems to have fallen asleep - if the snot bubble is anything to go by, never mind the still-open eyes boring into him - and the conversation has ceased, the ache in his knee has returned.

He closes his eyes anyway, trying to ignore the pain - it certainly isn't the worst he's ever felt, far from it, actually - but he can't fall asleep.

A/N: Apologies for the dryness of this chapter! But I felt like there needed to be an exchange of this kind of information between Kakashi and Reborn, so here it is. I think things will pick up next time. Obito's going to be conscious for it, at any rate, so that'll be a good time.

An anonymous reviewer asked if this fic will be told from Kakashi's POV or if others would be added - the bulk of the narrative will indeed be from Kakashi's POV, but there will probably be a few parts from Obito's. There won't be any from the KHR! characters' POV, though I might do some side stories about them later. Might, there is a very big might in there. Reader interest will, of course, be an influence on that. ;)