Disclaimer: Don't own Naruto or any related works, characters included.

Rating: T

As the title and summary have 'hinted', this is a fic exploring the what-if of Hinata developing the Tenseigan. Not every single moment of development or training for it, yet the overall gist will be covered - some romance and other characters will be involved as well.

Hope you all enjoy.

Home

"You ready, Hinata?"

Standing beside him, smiling, she nodded as she looked up at the sky - the moon hung above them, a small orb glowing with the sun's reflected light, which was the only source that lit up their backyard. Holding Naruto's hand, she held the other to her chest and closed her eyes... carefully, she focused Hamura's chakra inside and ran it through her pathway, excepting that of her head/eyes...

"Toneri" she spoke, looking up. "Please, if you're watching us now, I want to talk to you. I have some questions that need answering."

For a few seconds nothing happened - the wind picked up, and Naruto kept careful focus all around them, but shook his head.

"Please; it's important to us, before I try out the Tenseigan-" she tried again.

"Well that certainly demands my attention."

Mere milliseconds before that statement was made, Naruto turned in it's direction- she wasn't as fast, but Hinata quickly saw the figure above them. Lit from behind by the moon, standing on some levitating platform, it looked like Toneri in every detail... except one.

"You have eyes" Naruto noted faintly, his grip on her hand a little tighter. "You must be a puppet then."

"Indeed" Toneri spoke, looking/sounding the part otherwise - even as he spoke, the device lowered him to just above their level, slowly glancing at her. "So Hinata... you plan to pursue the powers of the Tenseigan."

Hinata made a sound. "Do you disapprove?"

After a moment, his eyes closed, a small ghost of a smile on his face. "Before, I absolutely would have" he stated, touches of regret audible. "Now though, I know that you are both honorable people; you do not pursue power merely to have it, but for the sake of loved ones. I believe that is your reason for this meeting, Hinata."

"Yes" she whispered, stepping forward a little, keeping Naruto's hand in hers. "As I understand it, I can develop the Tenseigan because of Hamura's chakra. And if I have the capability, I should experience it and use it's power when needed... we just have some concerns."

Beside her, Naruto added his other hand to theirs, smiling a little- she returned it.

Toneri opened his eyes. "Go on."

"Guess I'll go first" Naruto whispered, she nodding to show it's okay, then he looked over. "Toneri, if Hinata gets the Tenseigan, what will happen to her Byakugan? I mean, will she still be able to use those abilities?"

A moment passed, Toneri glancing up at the moon behind him. "Much like the Sharingan, in addition to it's advanced form and the Rinnegan, the Byakugan and Tenseigan all have great power" he started. "Those who naturally possess them will have full access, but those with implanted eyes do not, among other various drawbacks. Because I had already given my eyes, the ones I took..."

"...didn't allow you to use both variants" Hinata finished, fainter and hearing his regret. "So that means if I develop the Tenseigan, I could, Toneri?"

"Yes" he answered, looking back at her. "Regardless of whether you switch between them at will, or wield a combined version unique to you, you would indeed have full access, Hinata."

So she wouldn't lose her Byakugan abilities... at worst, maybe the appearance of her eyes would be forever changed, but that's something that could be adjusted to. She smiled with relief, a feeling enhanced by Naruto's small grin - she was about to say 'thank you' too, until they noticed Toneri reaching inside a fold of his clothes.

"Here" Toneri stated, pulling two scrolls from there. "One covers data regarding the Tenseigan; it should answer many of your questions. I have had it deciphered in your language."

"And the second one?" Naruto asked for her.

"Some scarce information about the Otsutsuki clan. I believe Sasuke Uchiha is searching for such, regarding the plans of my ancestor."

His ancestor... he must be talking about Kaguya; Hinata had never seen her, but from all reports she'd been a powerful opponent. A quick look at Naruto's expression showed some inward remembering of that battle, and she squeezed his hand in support- he appreciated it.

"Thanks, Toneri" Naruto breathed, sincere. "I know he'll appreciate this, as do we."

Toneri's only answer was to toss the scrolls at them, both of them catching one. "Thank you" Hinata whispered, equally sincere - the puppet's ghost-of-a-smile returned for a little, before it's eyes closed and the device began to rise back into the sky.

"One piece of advice, Hinata" he said, still climbing. "When the Tenseigan is maturing, try to avoid using any Visual Jutsu abilities; they can slow it down, increase the level of pain, or even destabilize the process. But besides that, I entrust you both to help keep this planet at peace."

And with that, his puppet's form was just gone.

Wind blew across them again, moving at her hair, but Hinata smiled again- "We will, Toneri" she breathed gently. "Count on it."

Naruto was smiling too, holding that other scroll... with barely a sound, he motioned for them to go back inside, and she gladly followed after a bit.

...

Inside, seated side-by-side, she looked over the scroll along with Naruto.

"So the Tenseigan appears immediately, after the chakra works it's way into the eyes" Hinata thought, her finger tracing each line. "For Toneri, he merely had to do a quick-and-easy burst, since his chakra is that of the Otsutsuki clan... for me, I haven't used Hamura's chakra much, and never into the chakra points around my eyes."

And according to this, once she started the process it'd truly be continuous; awake or asleep, it didn't matter.

"Mmh" Naruto breathed beside her, discontent. "I don't like it."

"What?"

"This painful pulse thing in the eyes" he whispered, looking at her, fingers moving over her hand. "Why does it have to be that way?"

Gently, Hinata held his hand back, rubbing a little and even kissing it. "I think, because that's the way it is" she whispered, understanding where he came from. "After all, our Visual Jutsus are descended from Toneri's clan, one way or another - and like the Mangekyo Sharingan, it requires some form of pain. I don't like it either, Naruto, but how can we change it overnight?"

A few moments passed. "Haven't a clue, Hinata" Naruto breathed, leaning over to kiss her cheek, which she liked. "But still."

She just smiled, leaning for her own kiss on the lips- Naruto didn't mind. "I know."

A little after, they returned to reading the scroll - they didn't like pain, but they were trained to face it. Naruto wouldn't like watching this be unable to do anything, and she wouldn't like it either but they could handle it... especially since this pain wouldn't physically harm her in any way.

"When the Tenseigan first manifests, it's fragile" Naruto breathed, reading out loud to himself. "If the user's chakra is severely weakened during this state, there is a high chance the Tenseigan will fade away."

Hinata remembered: immediately after Naruto clobbered Toneri, leaving him too weak to move at first, his eyes had faded almost immediately. She looked at that section herself, further reading that this state started upon the Tenseigan's initial transformation, and full maturation would only be the halfway point. Apparently this could be determined by the white floral patterns upon the eyes, which moved at different speeds depending on how far... early on, Toneri's eye patterns hadn't moved at all, but that seemed consistent with the writings. It also noted that for those who developed the Tenseigan with eyes other than their natural ones, they'd be unable to move past the full maturation stage- in other words, they'd constantly be at risk of losing their powers should they be defeated.

"But for me, because my Byakugan are my own, the Tenseigan could fully mature" Hinata thought, head tilted. "And after that, 'synchronize' with my body to become a part of me. Still limited by chakra, but it wouldn't ever fade away were I to lose too much."

Only question was, how much was 'too much' regarding the Tenseigan's conditions? Mmh- mmh- there: "Regarding the Tenseigan fading, the loss of chakra needed varies among each user. The highest recorded amount for this was fifty percent, whereas the lowest was one percent."

Alright, so she can definitely set above-half as her safe zone - though then again, it's not like she's gonna go full-out before it's matured. She may have the powers of the Tenseigan, both observed from Toneri and possibly others, but that doesn't mean she's gonna get them right away - for one thing, gravitational manipulation is the first needing a handle on. Then once the Tenseigan has synchronized with her body, only then would she test that 'chakra mode' she'd seen Toneri use, and what she can really do with it... which if it's able to provide a challenge to Naruto's Six Paths Sage Mode, was quite a bunch. Though practicing that much power was gonna be dangerous, and she didn't want to risk the village or anyone else...

Mmh.

Hinata slowly smiled, thinking it's so interesting. "I think that... that I want to try this" she whispered, taking Naruto's hand-

-who squeezed it back. "You sure, Hinata?" he asked, worried (about the pain angle). "Really sure?"

"Yes. I won't be able to avoid the pain, but I think the sooner it's over with, the better."

...

Hinata- mmh.

Sure, he knew she'd be really okay and everything, but watching her have to suffer and being unable to help- what's he supposed to do, just watch? Like hell... and yet there's literally nothing he can think of doing that'd help her... after all, this is a Visual Jutsu that's maturing over her normal Byakugan, adapting to her body.

The pain's temporary; just gotta keep telling himself that.

"Naruto?" Hinata whispered, turned toward him.

Naruto smiled a little; here he is worried about her, but it's him she's most worried about. "As ready as I'll ever be, I guess" he breathed, slowly nodding. "I don't like it, Hinata, but I'll get by somehow, ya know."

She smiled, gently taking his hand, playing with his fingers a little. "We both will" Hinata gently assured, to which he nodded. "Okay?"

"Yeah."

Still holding his hand, Hinata closed her eyes and took a deep breath... internally, Naruto felt Kurama interested in this, sensing the flow of her chakra and having him share this 'vision'. He saw Hinata's Chakra Pathway System as a result, or at least sensed what's going on inside: Hamura's chakra started to flow throughout her body, going through until it'd enveloped every point save a single path, ie the one into her head.

It hesitated slightly then went in, flowing into the chakra points around her brain and eyes; there was a reaction in the latter almost immediately, enough that Hinata made a sound, hands going over her eyes.

"Hinata!"

"I'm fine, Naruto" she breathed, making a sound. "It's just- it's just throbbing, that's all."

He knew that but still didn't like it... vaguely, he remembered Toneri almost bent to the ground, before he and Hinata went to destroy the Tenseigan device. That must've been the final one, painful enough to make him curl up, but otherwise didn't physically hurt him.

Thankfully for Hinata, this burst didn't last more than about thirty seconds- she let out a breath, raising her head with eyes still closed.

"It's stopped" she whispered, a little reassuring. "I'm fine."

"I hope so" Naruto whispered back, taking her hands. "But Hinata, did it work?"

Taking in another breath, she opened her eyes in stages, eyelashes making it difficult to see at first- still partway closed, she tilted her head. "I still see the same as I do normally" she whispered, more gentle. "That's good."

A little smile. "Yeah."

Hinata then fully opened her eyes, blinking once - no doubt about it: they're the Tenseigan, floral irises utterly still at first glance. Just like the scroll said; they'd continuously be Tenseigan while maturing, with the irises' speed determining what stage they're at... when he leaned closer for a more intent look though, they were moving very slowly, but it's almost impossible to make out in the first place.

She moved a little at his closeness, but didn't mind. "I take it that it worked, Naruto?" Hinata whispered softly. "It's the Tenseigan?"

"Yup" Naruto assured, squeezing her hands. "Though it's kinda silly that we're gonna sleep soon, considering you just made it..."

She leaned closer, kissing him on the lips, which he didn't mind- Hinata traced his whisker markings. "As Toneri said, it's best that I don't try anything with my new eyes, not until it's matured at least. Plus it's nighttime and everything."

"Hehe."

Hinata giggled as well, before she moved away- she looked at her nearby reflection, making a sound in curiosity. "That's definitely it" she breathed, even as he slid closer.

"Well either way" he breathed in her ear, to her small jolt. "I still think they're quite lovely, your eyes. They always will be."

She turned toward him, cheeks a little pink but happy. "You would say that, Naruto" Hinata whispered. "Come here."

Heart beating a little faster, he easily leaned closer.

Konoha

The next day

Okay, okay, got most of the groceries on this list, and just one other place to visit... mmh but it's so far away, being on the other side of the village. Hehe, not that he couldn't get there in fifteen minutes or nothing if he jumped from building to building, but still.

So best get started-

-hmm? Isn't that...?

It was Sasuke, walking through a nearby street with a few bags slung over one shoulder. "Sasuke!" he called over, running.

"Well, if it isn't you" Sasuke stated, back to him yet having stopped; he sounded amused. "If this isn't important, you've only got a minute."

Naruto just chuckled. "Yeah, whatever" he brushed off, grinning a little. "I'm glad I caught up to you, Sasuke, because you've gotta come over."

What sounded like a 'Hmph', but not dismissive. "Is that another thinly-disguised offer, Naruto?" Sasuke asked, turning his head slightly.

"No, it's serious" he said, before grinning. "Though it wouldn't hurt you to join us every once in awhile; a little double-date action and stuff."

A small exasperated sigh, before Sasuke turned toward him. "You just can't resist" he stated wearily, yet with a little lip curve. "But besides that poor taste in teasing, if this is serious, I should see what's got you worked up. But if I find one hint that you're baiting me-"

"-you'll be out the door faster than we can blink" Naruto finished, still grinning. "I got that drill memorized, ya know."

"Well that's a first."

He made a face then; Sasuke's always doing that, but it's his way of being playful... kinda, he thinks, but not like Sasuke would ever admit that.

/

A little later

Home

Humming to herself, Hinata worked the dishes as was her turn - she was a little distracted though, as her eyes had another painful pulse not long ago; could feel them getting stronger. This initially made her pause, remembering Toneri's most painful pulse had him literally clutching his face, sprawled on his knees.

Well, she knew that's coming; just gotta bear with it as they come - the front door opened just then- must be Naruto.

"Hinata!" her husband called. "I got us the stuff! Oh, and brought along Sasuke too!"

Really surprised, she quickly worked to dry her hands. "Coming, Naruto" she called back, before she moved into the living room, knowing the reason Sasuke's here - she saw them for a bit, Naruto smiling at her (she returned it), while Sasuke stood nearby glancing around the place. "You got everything?"

"Yeah, yeah" Naruto said easily, waving a hand. "Everything except the- gah, oh man I forgot! I ran into Sasuke just before getting the last items!"

Unnoticed by Naruto, Sasuke seemed to smirk, as if this wasn't a surprise.

"Then get back out there" Hinata encouraged. "While you're still thinking about it."

"You're right; later!"

"Wait, what about-?" Sasuke started to ask, but by the time he'd turned around Naruto was gone; he grunted. "And he's gone already... always in a rush" he grumbled, if just exasperated.

Hinata giggled, before turning to search for that scroll. "Well, that's Naruto for you" she said, quite gentle. "Still, regarding his reason for bringing you here, I can answer that just as easily."

"Mmh. And what exactly is this 'serious' thing he mentioned?"

One moment- here.

"Last night after hearing my request, one of Toneri's puppets briefly came down to Earth" she explained, standing up, delicately unlacing the string.

"Toneri- the guy who tried to send the Moon at Earth?"

"Yes" Hinata breathed, turning toward Sasuke. "We talked for a bit and he gave us a scroll, containing information about the Otsutsuki clan."

That definitely got his attention. "Well, how considerate" he mused, turning toward her - yet in that moment, Sasuke not only registered the scroll in her hands, but also- "What's with your eyes, Hinata?"

It's sooner than she'd expected, but they had to explained at some point. "Well, my Byakugan are changing into a new form, the Tenseigan" she breathed, stepping over with the scroll- Sasuke took it when she offered, gaze remaining on her. "It's the same as when you got your Rinnegan, only I'm using Hamura's chakra, since I've inherited it from saving Hanabi."

A few moments as he digested her words. "They any good?" he asked, eyebrow raised. "I'm assuming that since Toneri stole Hanbei's eyes, he had this 'Tenseigan' for a time."

She shifted, but nodded. "He went toe-to-toe with Naruto's Six Paths Sage Mode, with the strength to cut through the Moon's crust, while also powering the Moon's movement and a giant golem creature" Hinata chose to reply. "For right now though, my Tenseigan's still maturing so I can't do anything with it whatsoever. Plus if I were weakened enough before it fully settled, I'd lose it entirely."

"Well we can't have that" Sasuke noted, seeming interested; to her surprise, he actually had a tiny smile, however briefly it lasted. "After all, once this thing matures you're gonna need sparring partners and proper environments to cut loose upon, whether you keep up your training or not over the years. Naruto could easily do the former, but only I can take you somewhere where you wouldn't harm anyone with such powers."

Curious, she tilted her head.

"You remember our reports about Kaguya?"

After a few moments, she realized where this was going. "You mean, the other dimensions?" Hinata asked, surprised. "That's where you propose these sparring sessions should be?"

Sasuke shrugged. "Well, why not?" he asked, rhetorical. "They're empty, abandoned, with not a soul or civilization for miles. It's certainly better than leveling forests, mountains, or cities here during clashes."

Hinata wanted to say those wouldn't happen, but she couldn't; due to the power involved, even holding back could cause a bunch of explosions, shock-waves, and the like the closer she got to the Tenseigan's full power. Combined with her earlier thoughts, they're certainly more valid than anywhere else- she didn't think they'd be easily accessible though, knowing Sasuke's the only one who could freely traverse the dimensions.

"Well knowing how busy you can be, any chance you could reconfigure your space-time ninjutsu?" she asked - she didn't know it's specifics, but it couldn't hurt to ask. "Leave a dormant one for example, only to open if someone with Six Paths chakra touches it?"

He glanced up for a time. "That'd take some doing" Sasuke stated, before looking back at her. "At least a few days."

"That's fine" Hinata assured. "After all, the first thing I have to master is the Tenseigan's gravitational abilities- it and a few other things should take some time."

"Mmh."

/

At the same time

Finally got the stuff- honestly though, the walk/run home should've been normal.

"If Sasuke becomes interested in the Tenseigan's powers, he might join us in testing them out."

Naruto had to admit, that'd be cool... but Sasuke would need a reason first; if he had one without any prodding on their part, then great, but so far he wasn't sure if Sasuke would help. "Maybe, and I'll certainly ask if Hinata hasn't already, but you're just saying that because you sense a good fight."

"Well can you blame me? I'm stuck inside you most of the time."

"Yeah, keep sulking Kurama; you like it, ya know."

"Hmph!"

Naruto couldn't help but grin, shaking a little at his annoyance- but soon images were going through his head, not called by him. Battles- some from the War, but also their dual battle against Toneri and that giant Golem... after a moment, he felt Kurama was truly interested at the thought of Hinata's Tenseigan powers.

Well-

"Naruto!"

A bit surprised, he turned, seeing Sakura coming toward him. "Hey, what's up?"

"Not much right now" she breathed, but with a little smile. "Have you seen Sasuke? We were supposed to meet up-"

"Oh, sorry about that" Naruto answered, sheepish. "I found him earlier, and we had something important to talk about, so I invited him to our house; he's probably still there with Hinata."

Sakura looked a little exasperated, but nodded. "Well, hope you don't mind if I go with you" she said, starting to walk already. "After all, he's still flaking on our join-up plan."

"Nah that's fine, really."

/

"So that's what you're gonna have to do."

Hinata slowly nodded - based on what she's seen, Toneri's Tenseigan Chakra Mode had made use of those Truth-Seeking Balls, which were composed of the five basic elemental natures, as well as could be infused with Yin-Yang Style by all indications. If nothing else, she'll have access to all that once her Tenseigan's matured, but what jutsu she uses will be up to her... she'd definitely have to think about that later.

"If what you say is true, I could use Yin-Yang Style on them to neutralize any ninjutsu thrown at me" she ventured. "If I heard right."

A small smirk, even as Sasuke sipped his drink. "You could, but it's not exclusive; I can neutralize any ninjutsu you throw at me using the Rinnegan's chakra absorption path" he stated. "On the other hand, Naruto can quite easily counter the orbs with senjutsu chakra, and if he decides to bust out his own... you could fight them with your own, but otherwise lack the ability to counter them."

"Yes" Hinata acknowledged. "But I'm not sure that I'd win against Naruto in a fully-serious battle anyway. Maybe overpower him for a time, match him move-for-move, but he has Kurama's chakra in addition to his own. Mine can't match their combined reserves, even with the power of the Tenseigan, not from what I've seen from Toneri anyway. And you have similar levels of power, if not as much chakra on your own."

"It'd make a hell of a fight though" Sasuke mused, half-crossing his arms - much like Naruto's right arm, his left one remained covered in bandages. "You vs. either of us alone for certain, particularly since you have all of Hamura's chakra, whereas I and Naruto only have 'half' of Hagoromo's. Hmm, but if either one of us is too much to handle... what about teaming up?"

Really surprised, she looked at him-

-he shrugged. "It's just a thought" he said, sounding impassive. "You're the one calling the shots, since this is your new-found Visual Jutsu, Hinata."

Hinata was about to answer when the door opened, and she looked over to see Naruto and Sakura enter. Sasuke barely glanced over, but raised an eyebrow when he saw Sakura, though that's all the outward reaction he gave - Naruto saw her, giving a little sheepish grin as he raised the small bag, showing he'd gotten the last few things, to which she nodded with a smile.

Meanwhile: "What are you doing here, Sasuke?" Sakura asked, walking over to him. "I thought we agreed to meet up."

"We did" he said with a shrug, before gesturing at Naruto. "I was then set upon by this idiot (Hinata made a sound), and had something slightly more important forced upon me."

"Yeah yeah, 'forced'" Naruto grumbled, shaking his head as he quickly put things away nearby.

"Well, what's 'slightly' more important?" Sakura continued, more curious - Sasuke's only answer was to give her the scroll, which she unrolled. A quick scan changed her expression, and she re-rolled it before giving it back, which Sasuke did without looking: "Well, that should help a lot" she continued, a bit gentler before tilting her head. "But it doesn't explain why you stuck around, particularly since Naruto didn't make you."

Hinata stood up then. "That's my doing, Sakura" she said, preparing herself for explanation again.

"Hmm?" Sakura breathed, looking at her- much like Sasuke, she instantly noticed the change in her eyes. "What the-?" she breathed, stepping very close, critically looking them over (complete with hands holding her head). "Hinata, is that-?"

"The Tenseigan" she answered, sincere. "The same Visual Jutsu Toneri had for a time, Sakura; I chose to try this out, because I'm able to."

A little as her friend digested that. "But your report said Toneri suffered from painful pulses" Sakura said, worried. "Are you in any pain right now?"

"Not right now. More pulses will be unavoidable, but they won't physically damage my eyes; Toneri's other scroll explained so in detail."

Even so, Sakura had quite a few questions; she insisted upon looking at the scroll in detail, her medical training kicking in no doubt. Sasuke even deigned to look it over briefly, while Hinata did her best to answer the questions posed to her; the entire time though, once Naruto finished putting things away, he never left her side or let go of her hand.

Pure set-up for this first chapter, which had to be done since the Tenseigan takes time to form, and all that. But every other part of this eight-chapter fic will otherwise involve physical training, learning, etc ;)

Meanwhile, my planned update schedule for this fic will be every-other-day.