This is my take on the challenge based on the oneshot Kyuubi's Plan by Sage of FanFiction.
I would just like to say I do not own Naruto or any of the other things I pay homage too. If you like one of my ideas please, feel free to use them in your own stories, though I would appreciate a PM so I can read them.
He had been doing so well. He had successfully managed the kagebushin no jutsu in a single hour highly impressing the old man Hokage. It had certainly not been easy with the sudden fluctuations his chakra kept going through at an ever increasing rate. Though one useful side effect to the fluctuations was that no matter how many times he practiced the jutsu his reserves would suddenly flood back to and past full with each surge of power.
Having completed his special genin exam so fast gave him plenty of time to plan out and get supplies for the trap that he would set up for his errant sensei. He had lain a razor wire net as the primary trap hoping that it would be enough but had with the help of his new clones trapped the forest surrounding the clearing with numerous secondary traps that would only become primed with the release of the net. He figured if Mizuki were to manage to dodge the first trap then having backups surrounding the area that he could pass through coming into the clearing but became active on the failure of the prime trap would ensure success by preventing him from leaving.
During the wait for midnight when the clone he had left to 'steal the forbidden scroll' would be coming to act as bait he began to notice that with each surge of power his senses that had already begun growing in strength became even sharper. He also noticed that he seemed to be gaining some new type of sensation that he had never been aware of before. Concentrating on the new stimuli he realized it was much like hearing several different sounds or smelling several different things at once. Focusing on just the one that he felt the strongest he felt his eyes drawn to a certain place and realized upon looking closer that it was one of the concealed Anbu whom, had this new sensation not helped, he would have never seen.
Concentrating again he quickly scanned the area and was quickly able to pick out three others again concealed beyond his skill to pick out normally. Expanding his focus outward he quickly realized what it was he was feeling. At first he had thought he could somehow sense people but then he had noticed that no more than a mile away one of the sensations seemed to cut off and expanding ever outward he was able to feel a curved sphere shape that he soon realized encompassed the entirety of Konoha. You can't make an invisible dome of people but one thing you can make is a barrier of chakra. He could feel chakra and for quite a distance from what he could tell.
Narrowing down the area he was actively focusing on he realized that his clone was coming. It arrived and dropped off the fake scroll the old man had supplied him before dispelling giving him a quick laugh since the clone had knocked out the old Hokage with his orioki no jutsu. Focusing on the village he could feel a sudden large movement of people as their little plan went into effect.
Then the problem came. He felt not just one but two chakra signatures coming into the forest behind the Hokage mountain, though one was a significant distance behind the other. Moments later the first arrived and proceeded to drop into the clearing causing his heart to drop. As usual after one of his pranks Iruka had been the first to catch up to him though he was too angry to look for the traps Naruto usually set up to discourage pursuit.
Dashing forward with a shout of, "No! Iruka Sensei!" he hoped he would be close enough to push him out of the net before it trapped them when suddenly he felt the biggest surge of chakra yet and momentarily blacked out.
With a start he awakened in a darkened tunnel through which a shallow stream flowed. Taking to his feet he observed his surroundings. The only visible light source seemed to be a set of glowing pipes flowing overhead. He could see one glowing red and pulsing strongly like some sort of heartbeat while a second blue one seemed to pulse in counterpoint and if he was not mistaken grow with each pulse.
He quickly decided to follow the tunnel in an attempt to find a way out as there was no obvious entrance at his current location. Rushing down the tunnel he decided to remain on the main path that followed the two pipes to their source whenever he passed darkened offshoot tunnels. Finally he came to the end of the tunnel where the blue pipe passed into a wall while the red pipe continued across the massive chamber he had come into and through a huge gate with a small sealing tag holding it shut.
Moving closer he saw the pipe plunge into a massive glowing red orb on the other side of the gate with a small trail of energy connecting it to the massive form of what had to be the Kyuubi sealed within him.
"So I'm inside the seal somehow?" he thought aloud.
"No you're in your mindscape at the interface between minds," the tired seeming fox grumbled.
"Well then I guess the pertinent question is why am I here?" he asked the fox.
"I have moved on from this life so to speak. What you see before you is something of a clone with my knowledge to share with you much like the clone you just learned. I am leaving my power to you to do with as you want," the gravelly voice responded.
"So how do I get back out? I was in the middle of a problematic situation," Naruto asked.
"Do not worry. I am using my yin chakra to alter our perception of time within your mindscape so that we have plenty of time for our conversation," the fox clone told him.
"I see, then I suppose that the next question is why are you doing this?" he now asked.
"I had an opportunity to escape the seal but to do so necessitated my sacrificing almost all of my power which would have anchored me here. Thus I made some changes to your body so that the power would not destroy you once you claimed it as much of my chakra is toxic to normal living beings," it responded.
"Ah so the seal on my back was probably never real," he said knowingly.
"True, it provides you with a safer answer than that I had been enhancing your DNA," the fox said.
"But still this doesn't tell me why you changed me," the boy stated.
"It is a long story so you might want to form a seat for yourself," said the clone.
'Let's see this is my mindscape so I guess I just think of a chair and it will be there,' Naruto contemplated. Focusing his thoughts he remembered the big chair that the old man Hokage sat in and with a minor exertion of effort it did appear as he had hoped. He took his seat and awaited the explanation.
"Hmm, I suppose I should start from the beginning. A long time ago a great man that your people now days call the Rikudo Sennin fought the first of the biju known as the juubi or ten tails. It's might was greater than anything in this world and corrupt beyond measure but the sage devised a method of containing it by sealing it within his own body making him the first jinchuriki," it began explaining.
"I see but you say it was the first of the biju?" Naruto asked.
"Yes, when the sage's life was nearing its end he called upon nine powerful summoning contracts which he possessed. To each of the nine beasts he had summoned he gave a portion of the great juubi's power. Unfortunately each of us was driven to madness by the corrupting influence of the power. When our summoning ended we were returned to our peoples where we began to slaughter them indiscriminately. I understand that the slugs got lucky though as the sage's second son had signed their contract and had summoned the rokubi before it could destroy its entire clan," it stated sadly.
"So the other eight clans were destroyed?" he questioned.
"I know not if the other seven were completely decimated but am certain that I killed all of the kitsune before destroying our home completely. As far as I know though, I was the last to be summoned back to the elemental nations a mere sixty or so years ago. Due to the corrupt chakra flowing through us that came from the same origin we can somewhat sense each other and all the others were already here though each had been sealed in some way," the fox answered.
"So you were roaming free around the elemental nations for almost fifty years?" he asked.
"No, I was free only perhaps a year when Madara Uchiha came and controlled me with his bloodline. He then used me to fight his bitter rival the first Hokage though that effort was doomed to failure as that man had the mokuton bloodline which could weaken and bind my power while his wife who was also there had the Uzumaki special chakra which could further bind me until she sealed me within herself becoming my first jinchuriki," it told him.
"So you were sealed up until you attacked twelve years ago?" he queried.
"Yes though at that time I had already been transferred to my second jinchuriki, your mother. As she gave birth to you the seal was weakened and someone used that chance to extract me and set me upon your village once again with the Uchiha eye. Sadly among the lives I had taken that day both of your parents who were sealing me away within you were killed when your father sealed my yin essence away in the belly of the shinigami driving me into a yang driven rage which lead me to target you to attempt to prevent the sealing though both of them jumped in the way of my claw," it said with some remorse.
"If he sealed your yin essence away how do you have yin to maintain the change of perception you mentioned earlier?" Naruto wandered.
"You are the son of my previous jinchuriki, as such during her pregnancy you absorbed a portion of my energies making you perhaps one quarter kitsune. Had I not been sealed within you, one day you would have still been able to draw upon my power perhaps up to as much as three tails worth. That portion of my energy acted as a means for me to partially heal though much of my memory is damaged," the kitsune answered.
"So now you have escaped leaving me almost all of your power. What were the changes that you made to me to prevent your chakra from damaging me then?" he asked.
"I have made several enhancements to your natural form so that first of all you will be able to channel up to a full tail of my chakra without causing any harm to yourself. Though I have also strengthened you, enhanced your senses, opened your third eye that you may sense chakra, and awakened your dormant bloodlines," it told him.
"Bloodlines, as in multiple?" he asked with a little wonder.
"Yes you have three. Your kitsune energies have made you a natural shapeshifter. Most who use transformations can not use them in ways that make them stronger than their natural form in any way but you much like the Inuzuka who can take on the strengths of their bonded companions or the Akamichi who can magnify their strength by expanding their size can improve yourself, though your abilities are somewhat more powerful as it is a full bloodline instead of a special clan technique. Enhancing that bloodline I have given you three more powerful forms that you will be able to naturally shift into to allow you to draw upon three, six, and finally all nine tails of my power without harming yourself one day though the seal won't let you go past three until you obtain the key to open the flow," it explained.
"And the other two bloodlines?" Naruto queried.
"Your mother carried the Uzumaki special chakra which allows you unmatched mastery of chakra shape manipulation and several useful abilities as well as an expanded area of awareness with your third eye. All elemental bloodlines allow the masters to become one with their element and in the case of special chakra you can truly become one with chakra. You can refill willing allies chakra stores with your own and while linked with their chakra network can perform jutsu for them using your chakra and either your elements or theirs as long as you know techniques for their elements at least. Thus you can piggyback on a willing allies bloodline abilities. You will find it much easier to master the flow of jutsu to the point that you can do them seallessly and finally you can harden your chakra to such an extent that not even one of the biju can break through on strength alone. This was how your mother held me down while your father sealed me with chains of pure shaped chakra," the fox biju told him.
"I see that sounds awesome. So what is the final bloodline?" He finally asked.
"Your father somehow carried a small trace of the mokuton bloodline of the Senju clan. It allows you to control and sense plants and somehow even allows you to suppress the juubi's negative energies within the biju and now yourself. It is composed of a mix of earth and water element chakra meaning with your natural wind element which I shared and my fire element which will be imparted to you, you shall be able to easily master four of the five prime elements and one sub element. And since your father's natural element was lightning, it will perhaps not be too difficult to become competent in the fifth element," it answered.
"Hmm, I see and by your statements it appears that you know who my parents were," Naruto stated.
"Yes Kushina Uzumaki was my former prison so I was aware of her impending birth and of the father Minoto Namikaze. Jinchuriki are almost always chosen from among the relatives of the village leaders just as my first container was aunt to your mother and wife to the first Hokage you are the son of the previous container and the fourth Hokage," the fox clone told him.
"Ah so while my hero is the reason why you were sealed within me he also was one of the ones to give me the life to be in the situation. I shall have to make the best of the life they have given me in order to make them proud. So how do I use these abilities? I get that the transformations are just natural using my henge and the senses are just active but what about the special chakra and mokuton?" Naruto wandered.
"Well as you are the only one with these bloodlines as far as I know, until you can get ahold of the Uzumaki or Senju clan scrolls to learn techniques the only thing I think you can do is throw lots of chakra at what you want to happen and try to force your will upon that chakra. Much like you do with anything I suppose be stubborn enough and eventually it will work," the clone biju said.
"Okay then I had best get back to it and hope I can figure something out. How do I get out of here?" the boy asked.
"Just will yourself to leave," came the reply and with that Naruto was gone.
Naruto came too still mid lunge toward Iruka and feeling the massive upsurge of chakra decided that it would be put to best use in preventing the trap from triggering. Taking hold of it he thrust it into the surrounding ground and willed for something to prevent the net from releasing.
From the ground burst forth a large mass of grass which quickly bound the net preventing its release. Realizing he had to hurry and hide Iruka as Mizuki would soon arrive and as he was already in motion he thrust himself and the chunin with all his weight at a tree and pushed his chakra out at it opening a hole in its surface and then mostly sealing it back behind them leaving only a small crack to see through.
He then formed a shadow clone having it take his previous position and pulled the grass back from the net so that it would once again be set to trigger and began spreading his chakra out through the plant life in the forest.
"Just be silent and watch. I don't have time to explain my real mission sensei," Naruto quickly whispered placing his hand over the older shinobi's mouth.
Just as he finished they felt a reverberation through the tree as Mizuki arrived. "So you were able to get it well toss it to me and we will head back to the village and report how well you did," they heard him say.
"You know I get the feeling you're lying to me especially since this scroll actually has jutsu on it," the clone replied.
"Hmm you're smarter than you look though actually bringing the scroll suggests that you might be reasoned with. I was planning on taking the scroll and defecting leaving you to take the blame. The whole village is already out looking for you and they won't be lenient when they find you. Come with me and I'm sure Orochimaru-sama would have some use for you," Mizuki stated.
"Ehh it's not like I can ever become a ninja here so I guess," the clone said and held out the scroll it was holding. "Here take it and let's get out of here."
"Oh before we go I should tell you why the village hates you so much," Mizuki said.
At this statement Iruka tried to struggle but Naruto held tight.
"Yeah I already know about the demon fox that used to be sealed inside me," the clone said causing Iruka to stiffen.
"Used to?" Mizuki asked warily.
"Yeah it escaped during Ino's jutsu a month ago but was forced to leave behind most of its chakra so I guess I'm now becoming the new Kyubi while the former spirit has left. It's probably too weak to do any more damage than a regular ninja could now," the clone explained.
"And you didn't report it before now," Mizuki's panicked voice choked out.
"I didn't know until just now when I received its farewell message upon completion of my assimilation of its chakra, though I can only use one tail worth of the chakra in this form and would need to get the key to the seal in order to go beyond three. That is still Kage level chakra," the clone answered.
"Oh and my bloodlines activated as well," he nonchalantly added.
"What bloodlines?" Mizuki asked.
"Well from my mother Kushina Uzumaki I got the Uzumaki special chakra and because she was the previous junchuriki of the fox I gained a new kitsune bloodline. Then her husband had traces of Senju blood from which I got the Mokuton bloodline. Here let me show you," he said. With that chaos seemed to break loose as the clone transformed. He seemed to grow just a bit bigger as his nails became claws his teeth became fangs his whisker marks darkened and his eyes grew to slits. From the base of his spine grew three fox tails and his head grew fox ears. Then, from his back, two massive arms composed purely of chakra burst into motion reaching out for Mizuki while the entire forest seemed to come alive.
"Sorry I got impatient since he wasn't falling into the trap," Naruto murmured quietly to Iruka.
Dodging the arms and flailing grasping branches Mizuki realized that the trees were no longer safe and leaped to the ground racing towards the clone in an attempt to stop him. That was his final mistake as the net activated catching him and wrapping him up tightly.
Naruto then opened the trunk letting himself and Iruka out. "Well mission accomplished. And I even got him to confess that he was going to someone named Orochimaru," he stated.
Three anbu then revealed themselves and moved to take the prisoner. "That's three anbu but what about the fourth over there?" Naruto asked aloud while pointing him out. With that statement the fourth suddenly burst into motion running away. The three anbu then burst into motion chasing him leaving Mizuki for now.
"I guess whoever that was he wasn't supposed to be here," Naruto commented before forming a dozen clones and having them bind, gag, and cut down Mizuki.
"Well sensei we had best get him back to Hokage-sama," Naruto said turning to the dumfounded Iruka before setting off back to the village.