I don't own Naruto or his world and don't own quite a few of the core ideas presented. That proactively (as opposed to retroactively) applies to all future chapters of this story.
This story had a mix of influences. The basic premise is an idea I got from "The Empty Cage" by Rathanel, he uses it as an erroneous explanation by side characters for his protagonist's actions, while I am playing it straight. Basically, what if Naruto had his mind forcibly matured at an early age, and directly after the sealing he was placed in ANBU HQ for six months to a year? He would view the ANBU as his home, and try to get back to them.
ANBU Since Birth
Minato Namikaze had just finished sealing half of the Kyuubi into his newborn son Naruto. He was actually rather proud of himself; he had, on the fly, come up with a way to survive the sealing by feeding half of the Kyuubi directly to the Shinigami in exchange for his own soul.
Just coming off his high Minato started to feel weak.
"What's happening? I thought you said I'd live."
The Shinigami just chuckled "Just because you survive doesn't mean you get away unharmed. You and your wife have suffered major chakra poisoning, your coils will never fully heal."
While true, being in close proximity to both the Kyuubi's and Shinigami's chakra had made it so that Minato and Kushina were injured, the Shinigami was the one that had made it debilitating.
Nodding in acceptance, Minato crawled over to Kushina and held Naruto towards her.
Picking him up Kushina saying "Naruto, this is your mother, I probably won't get a chance to see you grow up, so I have few things to say." Then she started coughing
"Don't be a picky eater…eat heartily…so you grow big and strong! Take a bath everyday…and keep warm. And don't stay up late, get enough sleep. And make friends, you don't need a lot. Respect your sensei and senpai at the Academy. Oh, and more one important thing. About the 3 ninja vices, be especially careful when lending and borrowing money… and save the money you earn from missions and don't drink until you're 20 and drinking so much it's bad for you… take it easy! And… as for women… I'm a woman and I don't understand, but anyway… there are only men and women… so you will feel yourself interested in women… but just don't fall for a strange one! Find a woman like your mom. And speaking of vices… one more thing… watch out… for Jiraya-sensei…!"
Then Minato turned Naruto to face him
"Naruto, listen to your motor-mouth mother." Everything else of importance having already been said.
Unfortunately for them, it was all meaningless since Naruto would never remember any of it.
As Minato started to collapse he saw his student Kakashi and Hiruzen Sarutobi rush up to him.
"This is Naruto, I want the village to know that he is the hero that keeps them all safe. I want them to know that he holds back the Kyuubi."
"It will be done as you say Minato" replied Hiruzen, already formulating the ramifications of such a move. The boy would have to be kept absolutely safe, right now he couldn't rely on the normal channels to find someone, the village had just been under attack not ten minutes ago. But where could he find a place to keep Naruto and raise him till he could find a good home? The hospital was out, with how flooded they were, they were more likely to lose Naruto in the system than anything else, same thing with the orphanage. The retirees were out, they had just fought the Kyuubi, most of those that had survived the Second Shinobi World War were now dead, and those that were left were in no condition to take care of a child. No, anonymity wasn't possible right now, now he needed overkill.
"Medics! Get the Fourth and his wife to a secure spot and begin administering treatment. ANBU! Spread the word, the Fourth is down, I am assuming command!"
"Hokage-Sama, what is going to happen to little Naruto-kun?" Said Kakashi.
"Come on, let's talk in, what recurringly seems to be, my office."
As they both appeared in the office with a burst of smoke and swirl of leaves, Sarutobi started by saying
"Unfortunately it will not be possible for you to adopt him, no wait hear me out" Hiruzen said, thinking that was Kakashi's intention "first you are very young, not even fifteen yet, but also people would ask why you had adopted this child specifically, and then they would figure out who he is, and then they would never stop hunting him. So no I'm afraid I can't allow you to adopt Naruto-kun." Hiruzen sighed.
"So what will happen to him?"
"He will be taken to ANBU HQ till we can get this whole mess settled."
"Hokage-Sama…"
"Let me guess, you want to be inducted into ANBU to watch over him? Kakashi, you know that there is a sixth month probationary period to test for loyalty and mental stability, by that time Naruto may not even be living at HQ. Besides we have the village to clean up, and we need well known faces out on missions, showing that were are still strong enough to repel any opportunists."
"Hokage-Sama, I'd still like to do it, I don't think I can be a regular shinobi right now. Forming yet another team, making bonds with them and then being unable to do anything while they get hurt, and spending most of my time here in the village where there are nothing but bad memories for me here. I don't think I can do it right now, I'd much better be out in the field protecting the village that way, if I can." Kakashi, really never had any intention of adopting Naruto, he wasn't his godfather, and there was a bit of resentment lingering between his being the son of Kakashi's father figure and being physically associated with his sensei being incapacitated.
"Very well, you can start the probationary period in six months, if you still feel that way by then. That will give us a chance to stave off disaster, and with any luck, you will be in ANBU within a year."
"Thank you Hokage-Sama" and with that Kakashi shunshined out of the room.
"Now I just have to break the news to the council and make a public announcement about what happened. I'll have to do the council immediately, but the announcement will have to wait a few days."
With the Kyuubi
It had never been sealed in an infant before. The first girl had been an adult, the second almost an adolescent.
"What a novel experience. I can see the way that the chakra coils are developing, it's all so different from the times I was sealed before. It was so sad to see the last two driven insane. After all, if they hadn't tried to take me in after their coils had developed, I wouldn't have been tortured for the last hundred years." Thought the Kyuubi.
"Hmmm. What's this?"
Kyuubi watched as his youki, flowing through the young boy's chakra coils, started to react with Naruto's brain.
"So, maybe he will turn insane at that." Sighed the Kyuubi, resigned to another lifetime of senseless torture.
"At least this time there won't be anybody to corrupt him with the 'love' nonsense."
As Kyuubi continued to examine his jailor for the next couple of hours before he saw something that didn't make sense.
"What is going on there? It looks like the youki is actually permeating the grey matter."
"Ah ha! Now I get it, my youki is driving his brain to achieve peak development. THAT'S why the last two were driven insane; their brains were already mostly developed, so they process started developing their brains around what was already the highest priority. And since Uzumaki women, famously, lack emotional control, it boosted their focus on emotional satisfaction until they didn't it didn't even occur to them that their actions didn't make sense.
"Looking at the rate it's going, there might be some negative side effects, I'm going to have to try and regulate this process, the development of memory, the visual cortex, the eyes, and the basics for analysis can keep going at the current accelerated rate, but some of the other areas relating to language, personality and social interaction will have to wait until there is a good set of role models or they'd be permanently stunted by developing in a social vacuum. Have to get the right neural patterns going before prioritizing them."
Kyuubi thought for a moment.
"I guess I should start hardwiring a path from his senses to my cage, otherwise it'll not only be boring, but I won't be able to tell how to alter the current development program if I can't see what's going on out there."
With Sarutobi
It had been a long day, he had worked for the last 24 hours in the missions office, keeping work flowing through at a steady pace, regulating the village's recovery and helping moral by being seen to lead.
He remembered how the meeting with the council had gone
Flashback
"The Fourth managed to seal the Kyuubi-no-Kitsune at the cost of his life. Because of this I have re-assumed the position of Hokage."
There was an outcry at the first part, but it died down when he mentioned that he was once again in charge.
"What was the Kyuubi sealed into?" asked one of his councilors.
"A new born, Naruto Uzumaki, humans are the only thing capable of containing a tailed beast of that magnitude."
"Forgive me Hokage-Sama, but does that mean child lives?"
"Yes, and he must continue to live, if he dies then the Kyuubi will reform where he is buried after nine years." Sarutobi said before continuing
"Additionally, it was the last request of the Fourth that Uzumaki Naruto be seen as a hero for holding back the Kyuubi."
"One more thing Hokage-Sama, the clan name Uzumaki, are we to understand that he is the son of Kushina Uzumaki or another clan member?"
"No, that was something that was done in honor of the historical Uzumaki clan because of all they did to help contain the tailed beasts in the past." For those in the know the implication was clear, the container of the Kyuubi had been an Uzumaki for two generations, so the third generation would be an Uzumaki in name if not by birth.
Flashback End
"What next? Could this day possible get any worse? Oh wait there comes another stack of papers." He thought sarcastically.
Out of the corner of his eye Sarutobi saw the head of the medic squad that had taken the Fourth and his wife away. Sarutobi beckoned him over.
"ANBU clear the room!"
The medic bowed "Hokage-Sama, I came to give you a status update of the two patients" carefully not saying who those patients were.
"Go on"
"The chakra poisoning is severe; both patients are currently in a coma. We could try to use invasive medical procedures to help speed it up the recovery, but with the amount of damage their coils have sustained their bodies might think that any sign of foreign chakra was yet another attack upon it and fight back; which would almost certainly kill them."
"So what is the long term plan?"
"While the patients are in a coma at the moment, there is no way of telling how long that will last. If they wake up and start trying to be active in any way before their bodies are ready, it will kill them. I recommend a medically induced coma till their chakra coils can bleed off the corruption. Which, if my calculations are correct, will by about seven years."
"Damn, another seven years with this position, I had hoped to be retired for good" said Sarutobi.
"Oh no sir. That is seven years to get to the point that they can wake up and sustain basic medical procedures, there will have to be several years of rehabilitation on top of that, and even then it is highly doubtful that either of them will ever be at the same level they were at before."
"I don't have to tell you how sensitive this information it, so your team will be the only ones to deal with them until they are back on their feet. I want you put but a genjutsu seal on them, that wouldn't interact with their chakra just conceal their appearances, and give them a private room in the long term ward of the hospital."
"Why in the general hospital sir?"
"Hiding them in plain sight. Spies always try to ferret out unusual guard patterns that are used to protect hidden locations and sensitive items, but by placing them in an area that has standard guards and making your team responsible for that whole area we can make it legitimately seem like nothing interesting is going on there. And because of all the bloodlines in the village and the fact that so much can be determined by examining a shinobi's body, the hospital is already one of the most secure buildings in the village."
General Perspective
Naruto had been living in ANBU HQ for several months now. His memory had long since started being reliable; his first memory was of an ANBU team coming back from a mission, one man short.
"You just lost a team mate; in the past you've been told that this is worse than failing a mission, that the order of priority goes team then mission then self. In ANBU it's different, we're the janitors of the village, and the mission comes first. Just remember 'The mission is everything', and we got the mission done, so while yes it is sad, there is nothing to be ashamed of. "
With that the team all went off to mourn their fallen comrade.
Another memory that really stood out was when the ANBU commander gave a welcoming speech to a new batch of recruits, right after a chunin exam.
"…ANBU is like your family, not only your team mates, but the whole division is there for you because different teams often work together and if anybody on an operation is distracted or not working at peak proficiency the whole mission could end in failure."
Unknown to Naruto, the reason he could understand some of these things is that the Kyuubi was using what people said around him as a means of downloading language, social cues, and acceptable behavior into his mind. The Kyuubi couldn't download anything as complex as skills, he couldn't teach Naruto how to speak, walk or write and likewise he couldn't impart the meaning of a written character unless Naruto already know the spoken variant, but he could associate concepts and emotions with the things he perceived.
So it was that Naruto's first memory, was also where he got his first phrase, and at that age concepts that were reiterated like 'the mission comes first' 'the mission is everything' 'your pride is to always complete your mission' 'the mission is paramount' and 'ANBU is your family' became the founding concepts of his psyche.
Naruto's mind started to develop around values he saw at HQ like striving for perfection, because it will save the mission save your life and save those of your teammates. Or values like always being driven to succeed, being pragmatic (if it isn't useful don't do it), maintaining anonymity, and forming emotional attachments; form strong ones with your team, good ones with the division and a few strong connections outside of ANBU to keep your grounded, beyond that be prepared to have to kill anybody and always be aware that the life expectancy of those you care about and yourself is short.
Naruto also had trouble differentiating people by their faces. Humans usually learn from birth to look at faces and meet people's eyes in conversation in order to gain empathy, show respect, any number of things; Naruto had never learned these things. He had grown used to seeing everyone in ANBU masks that have obvious markings, when they walked around without the masks he had to try and figure out who they were based on height (difficult when you're a baby and everyone's a giant), gait, and coloration.
General consensus among his watchers was that Naruto was just an assignment, that isn't to say he didn't bond with them though. It probably didn't help that they encouraged his attempts at imitating them, ANBU are after all made up, primarily, out of no nonsense high achievers. When given a long term assignment to protect an infant who no one doubted would become a village shinobi, there's no reason not to push the kid from day one. During war time they kicked kids out on to the battlefield as young as five or six. Besides, the way the village was right now, war just might be on the horizon again, and if that happened they'd need their Jinchuriki out there fighting with them.
Naruto was routinely placed so he could watch the new recruits being broken in, since they were often the ones who got tasked to take care of his basic needs. It was because of this that he heard…
"If you fall short in your basic training you will be dropped from ANBU, if you fail to control your emotions you will be dropped from ANBU, if you fail to meet everyone with the proper level of respect and politeness you will be dropped from ANBU, if you are mentally unstable you will be dropped from ANBU."
The concept of being forced to leave his home and his family was terrifying, but his body still wasn't developed enough to do much more than babble and crawl.
He also got to observe a few basic instructions, he couldn't actually perform any justu since he couldn't mold or even manipulate chakra and hadn't done the mediation to find it, but he could remember the lectures about the basic techniques that they were supposed to know.
"This is the shadow clone jutsu, shadow clones are a solid construct that can be performed at risk by chunin level shinobi and safely by jounin, if you are going by the average chakra capacity per rank. They are used to get information in the field, they can do this because they are an alternative projection of your soul, in other words their knowledge and experience will feed back to you, it will do this automatically when they dispel, but due to the nature of these clones you can also gain that same information by choice. In ANBU we also use these to train certain things; even the weakest of you should be able to maintain one shadow clone for several hours, that is enough time to train taijutsu, kenjutsu, or shuriken-jutsu kata. Those with more chakra could use them to train chakra control or low level jutsu. This is a small part of the reason that ANBU are the best, we multiply our training resources. Now here is the hand sign."
Or
"This is the 'Hiding in shadow technique' this is a mainstay of ANBU since it allows, with chakra suppression, for us to hide in shadows. This is used during bodyguard work extensively, for instance Hokage-Sama's personal guard use this technique their entire shift. It is also used during infiltration and assassination missions to get through enemy territory, and for recon missions to hide and observe. Here are the hand signs."
Naruto tried to copy the hand signs, but with his tiny chubby hands he couldn't do more than make a fist! He could almost do monkey (hands laying on each other), dog (one hand resting on a fist) and he was getting closer to snake (fingers on both hands interlocked), but those were the simplest hand signs he'd seen.
Something that was repeated endlessly to the new recruits was that 'ANBU are thieves and assassins, they don't do combat' 'If you have to defend, you aren't fighting like ANBU' 'ANBU are subtle, so supplementary jutsu are good, but attack jutsu, i.e. most elemental jutsu, are too flashy for us'.
In all of this training the one thing that actually helped Naruto understand what chakra was, were the chakra suppression and sensing lesions. Which incidentally were the longest set of lesions the recruits had. It wasn't because the lecture meant all that much to him that Naruto was able to grasp what they mean, no it was because for several months half group would try to sense the area around them, and the other half would try to vanish from those senses. It allowed Naruto to feel what chakra was like in an environment, as well as what the absence of it was like.
An unforeseen side effect of being able to understand those around him was that there was never a time when he hadn't known about the Kyuubi being inside of him, or the fact that everyone said his surname had been assigned to him.
With Kyuubi
Kyuubi was feeling a bit smug.
He had spent the last ten months working tirelessly to mold his container into the foundations of someone actually worthwhile, a true shinobi, not one of the tactless imitators that filled the villages today.
The brain development rate didn't really translate perfectly into normal child years, a bit like dog years in that respect. The development was much faster for the first several months, then started to slow down and would finally finish at a state of basic maturation, but with room still to grow. Kyuubi projected project completion on the brain would be when Naruto was three.
The process of helping Naruto out by forcibly associating concepts to help him learn was a bit tricky, but he was aided by the fact that Naruto didn't know it wasn't normal to have ideas and knowledge just pop up, so thus far he hadn't questioned it.
The social development was also impressive. Naruto not only imitated actions and behaviors but understood many of the ideas behind them and accepted those ideas implicitly.
Sure there were probably going to be some odd ramifications from this, but Kyuubi didn't care so long as Naruto was decently sane, or at least controlled, and didn't embarrass him by being one of these flashy 'neo-ninja'.
General Perspective
After ten months Konoha had managed to stave off total disaster and wind down from the constant rush to repair the village and their reputation. So the Hokage figured it was finally safe enough to move Naruto to the orphanage.
With Sarutobi
He walked into ANBU HQ, finally it was time to take him to the orphanage, sure he wished there were a better alternative, a loving family he could give Naruto to, unfortunately there wasn't, but any childhood would surely be better than staying here.
He was met by the commander
"Here to collect our young charge are you?"
"Yes, anything to tell me about him before I take him?"
"Hmmm, it's hard to tell at that age, but possibly a bit brighter than most I'd say."
"That's good, we need more bright shinobi. What about his behavior here? Is he well-mannered, does he get to have any fun?"
"He's quiet, quick on the uptake. As for fun, this isn't a place for games, you know that."
"Yes, yes I do, but it doesn't hurt to ask how things are going."
"Here we are, he's just though there." The commander said as they came to the door.
Sarutobi walked up to Naruto
"Come here Naruto-kun, my name is Sarutobi Hiruzen, can you walk to me?"
Naruto thought for a moment while giving him a flat look, then toddled over.
Sarutobi picked him
"Well then, it's time to go now, I'm sure that you'll like it where we're going, there are lots of other children and people to play with you, and you can go outside."
Meanwhile, Naruto was wracking his brains trying to figure this out, go? Go where? To start with it couldn't be the medic or the barber, those were both done in house, then there was this guy holding him Sarutobi-san, he had never heard of him and he wasn't familiar, but the commander was deferential to him and that meant a high ranking outsider.
Sarutobi walked and walked, chattering to Naruto all the way about this and that, pointing out various landmarks and just generally showing enthusiasm. Till they came to the orphanage, where he met the matron at the gate.
Bowing low "Hokage-sama, I am at your service, anything I can do to help you."
"This is Naruto Uzumaki, he will me living here from now on." He replied while setting Naruto down.
"Yes of course Hokage-sama"
During their conversation though, Naruto was catatonic,
"Living here from now on! This wasn't possible, the only way that could happen is if I got dropped from ANBU, that man is the Hokage, he has direct authority over all the regular forces but usually goes through the commander to deal with ANBU. So I got dropped and they called for him to come and pick me up to dump me with civilians as punishment for how unworthy I am.
"What did I do wrong? Did I not try hard enough, did I lose control? Why did they drop me from the division? Maybe I'm on probation. Yes that must be it! That's why they had Hokage-Sama lead me to this place so they can watch my every move, they have me on probation until I show them that I have what it takes and can overcome whatever it was that got me kicked out in the first place."
While Naruto was trying to work it all out in his head as he was led away to a dark basement room that had clearly been used for storage not long ago.
The matron said "We have to take you in and we have to feed you, but we don't have to do a single thing more for you, so get used to it."
After which she shut the door
Naruto's last thought before collapsing from emotional exhaustion was
"I will earn my way back in, I must!"
AN: Having an insert character start training as an infant can be excused, and beginning training as an infant can work through flashbacks, but it takes a lot more work to explain it linearly and have it make sense. I mean, infants have bunched up muscles, low endurance, bad balance and poor flexibility. So without an adult helping him or an adult mind being able to understand how to force the body to do what it wants, it takes a lot of time and plot devices to make it all not seem ridiculous.
People have asked about clarifying what I mean by 'crazy' when it comes to Kushina. First, it's the Kyuubi's opinion that she's crazy. Second, she has zero impulse control added to rampant emotional outbursts, that is a massive personality disorder, many major personality disorders are labelled forms of insanity. Third, if she associates 'torture Kyuubi' and 'love' then she should be classified as yandere, and yandere are crazy. Fourth, I DO think that Minato would go for that, because I hate him.