A/N: Post Fourth-War. AU-ish.

Somehow, I couldn't get rid of the idea of Obito sacrificing himself just like Pein, reviving all the lives lost on the battlefield (- because it would be a heroic, beautiful death befitting of his personality).
Knowing this will never happen - and very much aware of the fact that Minato misses both arms - I wrote some kind of idyllic story of 'what could be': Minato (who has been revived) hanging out with Naruto, visiting Kakashi on a day off.
The story doesn't have much of a plot, but I wanted to try writing something that resembled a character-study, as well as exploring a little part of the development of ninjutsu, which I find thoroughly fascinating.

Please, enjoy!

Disclaimer: Naruto is not mine. I did create the 'Inner Warmth Enhancement Technique' though, but that's not really impressive...

Naruto followed his father onto the unknown grounds that were part of his genin-teacher's property. The blond had never known Kakashi used to be part of some clan, much less had he known that the man actually owned an empty family estate that came with private training grounds and a small shrine for a long-forgotten deity.

Minato had known of Kakashi's heritage, and though Naruto moved with curious wonder, his father moved silently, aware of possible traps, towards the wilderness that was the garden. It was a little better kept than it had been when Kakashi'd been just a boy trying to live on his own. The grass was tall and most of the bushes were overgrown, but it all seemed rather well-managed; it was a place owned by a man with not much time to spare and a garden too large to take care of all alone.

Naruto yelped when he tripped over a wire strung between two old bamboo poles he'd failed to notice. It was a remnant of Kakashi's earlier trap makings; easy to evade yet equally easy to overlook, and Minato smiled as he remembered the small but serious four-years old who had tried his uttermost best to improve his skills, going as far as setting up potentially harmful traps in the garden of his own home.
The boy who had grown into a man ever since, had not bothered to remove the clumsy work of his past self at the edges of the garden, and Minato now knew that Kakashi was sure to have erected powerful wards around the house itself, meaning he'd have to steer clear of the old estate unless they fancied a shocking death or painful injuries.

After dusting himself off, Naruto started chattering; he strongly resembled Kushina at that moment – they even shared the same nervous habits. He had inherited his mother's motor mouth, and though Minato would usually be happy to listen to the blabbering of his son now that he'd started spouting out some kind of nonsense about weird traps and somehow connecting them to ramen, the older blond was more focussed on the third person in the garden.

Hunched over on his knees and grey hair obscuring his face (or rather, the lone part that was not already covered by cloth), Kakashi looked very much out of breath and very unwell. Faster than the eye could see – and Naruto could follow – Minato ran to Kakashi's side, touching his shoulder in concern and comfort, "Are you all right?"

The older blond felt tremors race through Kakashi's body underneath his fingertips.

Naruto appeared next to them, his face serious and his eyes blazing with worry for his teacher. The teen kneeled in front of the kneeling man and asked, "Kakashi-sensei – hey, sensei?"

Kakashi looked up, surprised by the sudden company, and, though he was still breathing heavily, managed a smile and nodded. He politely brushed off Minato's hand and tried to stand, but his legs did not agree with his weight and immediately gave out underneath him. He slumped to the ground and leaned on his hands as he tried to catch his breath.
Naruto let out a surprised shout and tried to help Kakashi sit down in a more comfortable position, his hands fluttering everywhere, Kakashi swatting them away with ease. The teen's eyes were wide and he was quiet, not quite knowing what to say. Before Minato could ask anything, Kakashi said in between breaths, "G-give me a minute…"

There was humour in his voice neither blond male could place.

After what could've been a few minutes, Kakashi managed to calm his breathing. He closed his eye and ran a trembling hand through his hair. Minato waited for an explanation. Kakashi gave none.
After a while, it was Naruto who asked, both curious and a little irked, "What the hell happened, Kakashi-sensei?"

The grey-haired man smiled sheepishly underneath his mask, shrugged, and said, "I kind of managed to electrocute myself a little. Don't worry, I'm fine now."

Naruto's mouth fell open, "You what!?"

Minato let out a sigh, "Goodness, Kakashi, what did you do that caused you to shock yourself?"

For a moment, Minato remembered the stoic twelve-years old who'd been trying to develop a high-classed lightning-technique on his own, the stubborn student who had managed to burn his lower arm because he hadn't been careful enough in his vigour to complete it.
Somehow, the older blond had a feeling that Kakashi'd shocked himself because he'd been messing around with things he shouldn't mess with in general, and judging from the absolutely amused twinkle in Kakashi's eye, he'd been up to no good. Knowing that the Hatake was not a prankster at heart but wasn't without a sadistic streak, Minato just hoped his grown-up student hadn't taken after Obito's love for mischief.

Kakashi positively beamed – startling Naruto as he did so – and chuckled, "Maa, I'm just doing some research, but I miscalculated the amount of chakra needed for my… ah, experiment, thus ending up trying to transmit too much chakra into the dummy, causing it to be more electrically charged than I had intended. And then it shocked me."

"...I'm sorry, you what?" Naruto asked intelligently.
Minato just shook his head with a bemused smile, "Don't tell me you're developing some kind of jutsu…?"

Naruto's head moved frantically to the sides, "Jutsu? New jutsu? What are you trying to do, Kakashi-sensei?"

Kakashi stood up, albeit a little shakily, and answered Minato's question, completely disregarding Naruto.
"No, I've given up on developing my own jutsu after Chidori, Minato-sensei." Minato could almost taste Rin's name on his tongue and the regret that came with it. "But I'm still modifying techniques, if that is what you meant." Kakashi smiled, elevating the sadness that had overcome them with almost practiced ease.

"Sandaime-sama has been so kind to allow me to look into some parts of the forbidden library during my little stint in ANBU." He explained to Minato, who nodded in understanding.
The Sandaime had shared Minato's view on the young Hatake's silent but harmful frustrations back then, and the old man must've sought (and found!) a way to distract Kakashi from Minato's sudden death, which had caused a great deal of grief. Letting the talented boy to study varying types of chakra-theories and jutsu had probably been a good way to occupy his inquisitive mind, and it had tied him to the village irrevocably – Kakashi was loyal to a fault, and the trust Sarutobi-sama had put in him had most likely strengthened the bonds between the village and last Hatake.

The Sandaime had been as good with people as he'd been with jutsu, after all.

(Little did Minato know that Kakashi had more or less broken into the library himself with intentions of finding out more about Hirashirama and Mokuton-jutsu at first. Kakashi decided to keep that particular fact to himself; he wasn't lying about being granted entrance to the library anyways, seeing Sandaime had allowed him to come and go as he pleased afterwards).

Meanwhile, Naruto all but gaped at his former teacher; he was learning more about the man in one afternoon than he'd learnt in the five years he'd known him.
Kakashi continued in his usual offhanded manner, "I've always liked jutsu, and now that I have quite some spare time left these days, I thought I could try modifying some D or C ranked techniques using some of the theories I read about. It's interesting to do."

Minato nodded as he crossed his arms as he entered his so-called Teacher-mode, "I take it you've done the necessary research before experimenting with your own chakra?" He knew that Kakashi could take care of himself, but a voice in the corner of his mind told him that his grown up student still needed looking after at times (especially this shortly after war) and Minato couldn't shake it off.

Kakashi slipped his hands into his pockets and smirked, "Of course. What did you take me for? A Genin?" (Naruto's 'hey!' was purposely ignored).

"Yet your calculations were off." Minato set the bait. He was sure more was going on in that weird mind of Kakashi's than he was currently letting on.

"So they were." Kakashi agreed. There was an awkward pause. Minato resisted the urge to sigh. Kakashi turned his head to look at the clouds, faking professional innocence.

Completely oblivious to the sudden tension, Naruto was trying to get the attention of his father or his former teacher, but when neither man would answer his questions, he started skipping around them, trying to get their attention through physical means if it must.
Then, Naruto being Naruto, he tripped again and fell flat on his face. At his feet, there was a detached arm. Naruto screamed and scrambled away from the severed limb.

Before Minato could react or panic at his son's scream, Kakashi'd turned around and smacked Naruto on his head, "Relax, it's just part of the dummy I just destroyed." After a beat, "And you just tripped over it? My, my, did you ever listen to a word I said about noticing your surroundings?"

Naruto stuck out his tongue as he rubbed his sore head, "Bleh. You were a shitty teacher anyways!" Kakashi huffed undignified.

Shaking his head, Minato kneeled and picked up the arm, which looked as if it was a real human limb indeed. Looking further around him, he could see more charred remains of the destroyed dummy scattered in the grass, but there were no signs of explosion anywhere. Even so, the arm looked battered, and it was burnt at the fringes as if a fire had tried to consume it before it had been snuffed out.

"Just what kind of jutsu were you trying to modify, and how did you get your hands on a dummy from the hospital? I thought these models were meant for medical students who studied chakra-flow and circulation, not ninja who make a hobby out of electrocuting things. If I'm not mistaken the Research Department – or the Torture and Interrogation Department – have more qualified dummies to train with."

Kakashi took the severed limb from Minato and started walking towards the house, "Shizune let me borrow one. She's not getting it back now though... Would you two like something to drink?"

Changing the subject had never been subtler.

The off-handed question seemed to work nonetheless, because Naruto followed his former teacher like a puppy, "Do you have something to eat as well? I'm starving!"

Kakashi chuckled as he dispelled his wards with little more than a mere flick of his fingers as he lightly hopped onto the terrace. Grasses and other weeds grew through cracks in the wood, which had coloured green in some places because of the varying types of mosses that grew there. Ants seemed to have found residue underneath or near the house and the insects crawled in steady lines over the porch.
As the grey-haired man opened the door, Naruto peered inside with an almost childish curiosity. However, before he could enter, Kakashi pushed him aside without using much force. Minato caught his son's arm before he could follow after his former teacher. Kakashi disappeared into the hallway without saying anything.

Minato shook his head when Naruto turned to look at him questioningly, "Don't enter, Naruto. He hasn't invited you in; this is his…ah, 'territory', and I'm not sure if he's willing to share this place – his place – just yet."
Minato had half-expected Naruto to look at him incredulously and then ask something along the lines of, 'Why?'. It surprised him when Naruto didn't ask.

Naruto's face had softened at Minato's words and he looked at his sandals with a slight smile that could mean both sadness and happiness. "Of course."

Two words that conveyed a deep sense of understanding that caused Minato's breath to hitch; his son had a kindness in him that not many possessed, a sense of pain that had not turned into bitterness but rather into sympathy and – dare he'd say it – love. Naruto understood people in ways people did not understand themselves, and that was his greatest asset. Minato smiled at his son and squeezed his shoulder. Naruto looked up and grinned brightly.

Kushina would've been proud of him.

Kakashi emerged from the house with three bottles with water and a plate filled with slices of watermelon. The dummy's severed arm was tucked into his pouch and it looked rather creepy. Neither Minato nor Naruto commented on it, and Kakashi didn't seem to care if there was a frighteningly real arm sticking out of his pocket (and somehow, Minato was pretty sure it wasn't the first time Kakashi'd carried around severed limbs in his pockets. It was a quite disturbing thought).

They sat down at the edge of the terrace. Naruto hungrily consumed two third of the watermelon and Minato laughed sheepishly at his son's ravenous appetite. Kakashi watched the pair with an unreadable look on his face, but the older blond was sure he could detect a glimmer of fondness underneath Kakashi's carefully practiced blank stare.

"Kakashi-sensei, you're being creepy again." Naruto commented with his mouth stuffed with watermelon.
His former teacher sat up a little straighter, "Hey, that's not nice to say. Am I not allowed to watch my favourite student and teacher when they are enjoying their leisure time doing absolutely nothing?"

Minato laughed while Naruto glared at him – though it wasn't all that impressive due to his full mouth - and said: "No. It's creepy."

"You wound me so." Kakashi's drawled as he schooled his features into what could be a hurt look. Naruto steadily ignored him and focussed on his food.

Minato didn't quite know how to react on this easy banter his son and former student had fallen into. The Kakashi who was sitting with him on the terrace was completely different from the confused and humourless teen he'd left behind when he died. A lot had changed, but a lot had stayed the same as well: whereas Kakashi had been rigid and cold, he was now more relaxed and a little more approachable, but he'd retained his standoffish nature, seemed to have the emotional spectrum of a rock, and always was on guard still, even in his own garden.
In the end, Minato just asked, "But seriously, what were you working on with that dummy?" Ninjutsu had always been one of the many things that fascinated Minato. He was genuinely curious.

Kakashi crossed his legs turned his head so he could look at him, "I'll bore you."

Countering Kakashi's reply with a question, Minato grinned, "Have you forgotten that much about me already? I, too, am interested in jutsu – especially in the development of one. Indulge me, Kakashi-kun." To Minato's amusement, the grey-haired man got flustered and muttered something along the lines of 'I'd never forget something like that…'

For a moment, Minato didn't think Kakashi would elaborate, but then the man started talking. His tone was lazy, almost mockingly so, but there was an underlying seriousness in his words that betrayed Kakashi's commitment to this subject.

"Shortly after your death -" Blunt, as always, " -I copied a certain jutsu in the Land of Snow called the 'Internal Warmth Enhancement Technique'; it was some kind of method that was used to keep the body warm in cold situations, potentially saving the user from freezing to death. As you might know, the constant circulation of chakra through the pathways is part of the body's natural way to keep itself warm. Especially around the internal organs its flow is important, for it takes part in managing the core temperature. When facing situations that are most likely going to be very, very cold, like a blizzard or an ice-based jutsu, which are all likely causes for severe hypothermia, the Internal Warmth Enhancement Technique allows its user to quicken the chakra flow, which warms the body from the inside. It's a rather simple technique – D ranked, in fact – but it needs some concentration when used."

Kakashi was listing off facts as if he was reading aloud from a book.

"In Konoha, medics have further developed this technique after I had shown it to them. Its basics are the same – speeding up ones chakra flow to create warmth – but instead of preforming this technique on oneself, one performs it on someone else. Basically, you just let your chakra seep into the pathways of someone else and then force it to move through the pathways, letting it circulate through the body as though it is part of the natural chakra flow. As it moves, the patient's natural chakra will react to it in a mildly violent way. The combination of slight alarm in the pathways as well as a faster circulation heats up a body rather quickly. It is highly useful one someone's been almost frozen to death. I must say this particular technique evokes a pleasant feeling once you've regained consciousness. It's a pleasant warmth." Kakashi smiled.

Minato urged him to continue, "Medical techniques are rather difficult… D-ranked, you said?"

Kakashi nodded, "Once you get the hang of it, it isn't all that hard. It doesn't consume too much chakra as well, seeing only a little is needed to stimulate the flow without disrupting it. It's D-ranked I tell you. Also, it is one of the basics of medical training now. Sakura can probably explain it better than I just did, Naruto." Kakashi said to his former student as he opened his mouth to ask for a clearer – easier – explanation. Naruto frowned, but didn't ask. Minato raised an eyebrow, but Kakashi continued dismissively.

"Anyways, that was not what I was going to say. Though these techniques are the foundations of my experiment, I'm not working on medical jutsu. I'm no healer and I'm not trying to become one either. …Though, I did help developing some kind of blood-clothing technique once, but that was incidentally, really." Kakashi was lost in thought for a moment, a memory surfacing he could not seem to block out. His eye glazed over in thought, and Minato let him have his time to think.

Naruto suddenly disrupted the silence by asking, "Hey, do you guys want the last parts? Otherwise I'm just going to eat these…" He looked at the last two slices on the plate. Minato chuckled, "You can have them."

So far, Naruto hadn't understood a word of what Kakashi'd just spouted out, but the moment he started explaining again, the younger blond was all ears. The grey-haired man had finally started speaking of his own project, and to be honest, Naruto was curious about that, though he didn't quite get what was going on. Usually, Kakashi-sensei would be a little more explanative whenever he talked about some kind of jutsu, but for some reason, he seemed unwilling to say more on the subject than he had to. But that was nothing new, of course.

"Like the techniques mentioned before, the modification I was working on is based on the circulation of chakra. I thought that, if the flow can be sped up for medical purposes, it could also be used to paralyze victims. An irregular chakra flow is often rather destructive, if it's not some kind of genjutsu, but I'm not trying to create a technique to cause bodily (or mental) harm. Rather I wish to develop it to subdue enemies; therefore, on the matter of irregularity, to paralyze using chakra paths, the flow must be kept constant."

He took a breath, "Using the medic's version of the Inner Warmth Enhancement Technique, the flow will not be disrupted but merely sped up. When using a larger amount of chakra, the body it is used on will react. The victim will lose control of his own chakra, meaning he won't be able to create jutsu, and the body will temporary paralyze itself as it tries to undermine the invading chakra. Usually, the invasion of strange chakra causes disruptions, but this technique won't create disruptions of any kind, thus confusing the body. When infused with lightning-based chakra – like my own – paralysation should be immediate. Do you get it?" Kakashi asked.

Minato thought it over for a while, and Naruto just stared.

Kakashi laughed sheepishly, clearly unsettled, "Ah… Sorry, was that too much…? You asked for an explanation and I got a little carried away…" He stared at the ground.

"It's all right." Minato said, "But… I think you've forgotten to take something into account. You may be able to shock your enemies with your chakra, but invading someone's pathways is a little more complicated I think. I mean, you have to force your own chakra into someone else's system, which in itself is quite a feat in the middle of battle, and you've got to keep the flow steady. Without a massive chakra-source like Naruto's or Tsunade-hime's, you won't be able to pull it off."

Minato suggested: "I'm pretty sure it'd be easier if you could limit the technique to affecting the chakra flow near the brain, using the cluster of pathways in the back of the neck. Without cutting off or disturbing the flow near the brain, it should be easier to paralyze the victim. It's more like genjutsu that way, but it's more efficient. Also, if needed, you'd have direct access to the nervous system, and with your lightning-based chakra, manipulating a body into submission through chakra guidance wouldn't be all too hard… Though this technique is better suited to be used a medic rather than a full-time soldier, I guess."

Kakashi shook his head and he looked at Minato from the corner of his eye, "I've thought of that as well. But I thought it'd be interesting to take on something a little different from an assassination technique. I thought that this modified jutsu, if completed, could be used to keep prisoners in check without having to seal them."

Minato asked for more details and Kakashi provided them. They discussed different theories, countered each other's arguments and agreed on some points, developing Kakashi's modification in the process. The longer they talked, the more complicated terminology they used, and the more intricate the theories became; if Naruto hadn't been able to follow their conversation before, he now was completely at loss.

Though he really liked ninjutsu, he didn't really get the theoretical part.

Somewhere around the part the two teachers had started discussing the effects of chakra affinity on circulation, Naruto'd all but completely zoned out. He was getting a little bored, but he did not dare to interrupt.

Looking at the two men, Naruto couldn't help but like the way they discussed. He was only just getting to know his father, but he had known his father was a bit of a genius, and it was nice to see him in act like the genius people said he was. Gifted with words, a sharp mind, and an innate understanding of jutsu, all of Minato's qualities he'd been admired for were visible. Thorough the entire conversation, Minato's smile had steadily grown wider and his eyes were sparkling in a way Naruto could only describe as pure joy and giddiness. It was no wonder Minato'd developed a complex technique such as the Rasengan at young age – the man absolutely adored the workings of jutsu if this single discussion was anything to go by!

Naruto was very surprised by Kakashi's reactions though. Kakashi still looked as unaffected as ever, but he almost seemed eager; there was a spark of intelligence in his lone eye Naruto had never seen before, and the man absorbed information like a sponge absorbed water. For the first time in his life, Naruto saw his teacher come to life in a conversation, and for the first time in his life, he saw his teacher's brilliant mind fully at work.

Suddenly a thought struck Naruto: the grey-haired man was particularly bright, but he never spoke of his talents or interests, and never shared his ideas with anyone unless it was asked of him. Perhaps, aside from Kakashi's obvious disinterest in anything that had to do with being socially involved, Kakashi didn't share his interest in theories, research and development because he had not found an equal to discuss them with.
Sure, he and Naruto'd spoken of jutsu many times, but he'd often had to simplify explanations and never went into the theoretical aspect, Naruto also knew the man often talked to some of the fellow jounin, but so far, there'd been no one who would dare to disprove his theories and truly challenge him. (On an intellectual level. Gai challenged Kakashi in more ways than one, but that had nothing to do with ninjutsu).

Also, Naruto thought with glee, he'd found out one of Kakashi-sensei's supposedly many hobbies: fooling around with jutsu! The teen grinned to himself in some kind of victory while the two adults continued their conversation (which somehow had turned into some kind of debate about the (in)appropriateness of 'Konoha's Special Jutsu: One Thousand Years of Pain').

After a while, both men fell silent. Minato was grinning widely, and Kakashi's lips were quirked up in a sincere smile. The grey-haired man felt elated. Happy, even. Naruto seemed happy, too, as he lazed around on the porch. The teen had absolutely stuffed himself with watermelon and it almost seemed as if he could start purring like a happy, fat cat at any moment. Kakashi laughed to himself at the thought. Naruto shortly looked at him as if he'd lost his mind, but he didn't care.

In the garden, birds sang. The sun was slowly setting as the evening fell. Maybe he'd ask them to go home now. Maybe he'd just stay silent and bask in their blazing presences a little longer. Kakashi decided he liked the latter better. Actually, he wouldn't have minded it if he could stay like this forever, with both Minato and Naruto at his side. A moment of bliss he'd treasure forever, like a dream come true.

When Minato casually asked why he'd used a dummy from the hospital to practice and experiment on, Kakashi didn't really think of his answer and said truthfully, "When medical dummies are infused with chakra, the 'pathways' light up in places the chakra is flowing through. Now that I can no longer use the Sharingan to see chakra flow, I resorted to using one of these." If the air grew tense after his honest comment, he did not notice.

Minato, however, stilled after Kakashi's reply – knowing that honest answers were rare and in between when they concerned personal matters.
The blond mentally chided himself; he should've known the loss of Obito's eye would've affected Kakashi's methods on jutsu. He looked at the other man and searched for clues of possible emotional trouble. He found none, but Kakashi wasn't easy to read, especially when he decided his feelings were none of your business. Even so, the man did not display any of the tell tale signs that indicated emotional stress and actually looked as if he was still feeling the rush of the intellectual high he'd been in. Minato sighed in relief, happy Kakashi was feeling well and not bothered by anything for once.

Then Naruto asked, not because he was curious, but because he was clearly bored and searching a distraction: "But what's this jutsu you've been developing anyway, Kakashi-sensei? I didn't quite get your explanation. I still wanna know what it is though!"

Kakashi mulled over the question for a few seconds and said, "Naruto, could you create a shadow-clone? I'll show you." The teen cheered (Minato actually had to cover his ears from the loudness) and made a clone.

The second Naruto looked as pumped up as the real one. It wasn't often Kakashi shared something of himself with his students, and Naruto was thoroughly enjoying the fact seemed to be willing to do so now, even when the man was only stimulated to act like he did by the presence of the former Yondaime Hokage. And trying out – even if he was little different from a dummy now – a new jutsu was absolutely awesome in itself!

"All right. I want you to lay down, otherwise you might disappear when you fall down or something." Kakashi instructed the clone as he stood up and stretched his back. He lazily walked towards the fake Naruto, which laid down in the tall grass. Kakashi kneeled next to him, "I will not perform the entire jutsu on you, because it'll dispel you. I can give you a gist of what it should be like though."
The grey-haired man turned his head to look at his teacher, "Minato-sensei, will you observe closely?" He almost sounded hopeful; "It would be a great help if I want to finish this later." Minato nodded in confirmation, bemused by Kakashi's formal tone.

The real Naruto pumped his fists, "Show me, sensei~!"

Kakashi turned back to the clone, smiling cheerily, "Also, it might hurt."
The fake Naruto gulped, "If it hurts too much, I'm going to kick your ass!"
"Sure." Kakashi said, and he started forming the necessary handseals. Small sparks of electricity ran over his hands as he placed them just above fake Naruto's stomach.

"It tickles." The clone said. Kakashi continued to discharge energy.

After a few minutes, Kakashi ordered, "Move your arms."

"I can't!" The clone shouted in surprise, "Hey, hey! I can't!"

"Move your legs."

"I can't do that either! This is sooo cool! And it tickles!"

Kakashi removed his hands, "That's it." He wiped his brow and took a few deep breaths. He'd been practicing the entire day, and he was aware that he'd reached his limit. He had almost exhausted his chakra to the point that moving had started hurting, and his mind was drained now that it was no longer functioning at top speed or adjusting itself to the idea he was actually talking to Minato-sensei. Who had been dead for years.
When said Minato-sensei planted a warm hand on his shoulder, he almost lashed out in surprise. He had not noticed his approach and that made him uneasy. He wasn't sure if Minato'd noticed his sudden tension - an unwelcome feeling that was most likely fuelled by his chakra running low – but the blonde man did not remove his hand.

"Tired?" He asked instead, with his kind blue eyes sparkling in amusement. Ah, Minato-sensei probably knew he was a little more than physically fatigued, but he seemed to understand and grinned brightly at him.

For him.

Kakashi looked away and attempted to wrap his mind around the fact that he would be seeing that smile many times from now on. Kakashi sighed, but he couldn't help it when his eye closed into a happy, thankful arc as he smiled.
The fake Naruto disappeared and the real one jogged over to them.
Kakashi flopped onto his rear, the dummy's arm fell out of his pouch, "Perhaps I might be."

"Let's get dinner." Minato said. A light breeze ruffled his blonde hair. Naruto nodded in agreement, even though he'd just finished a huge 'snack'. The older blond held out his hand to help Kakashi up, but the grey-haired man didn't take it, choosing to get up by himself.

Before Kakashi could open his mouth to ask if Minato would be paying, Naruto gave him a knowing look that could give Ebishu a run for his money, "And I won't let you get away without paying this time!" Kakashi just shrugged, "We'll see about that."

Minato watched his grown up student and growing up son as they interacted. Kakashi'd pulled out one of Jiraiya's scandalous romans novels – Minato almost cringed when he thought about the contents of the bright green book– and Naruto shouted at him for being a lousy bastard and a pervert.

They left the Hatake family grounds in high spirits. Minato slung an arm around Naruto's shoulder, leaving Kakashi's personal bubble undisturbed, and he thought that maybe they could hang out with Sakura tomorrow.
They'd harassed Kakashi enough today, and she seemed a nice girl as well as very good friends with Naruto.

(And if she was his son's supposed crush, he might as well check if she'd be good for him. Minato still was a father, after all).