Disclaimer: I wish I owned Naruto but I do not. It is the property of Masashi Kishimoto. So don't sue me.
Cost of Life Fusion
I wont and never would be willing to become human. They are far too weak. Don't take offense to that kit, you weren't completely human to begin with. Because of me you were at least part demon, even if you were a hundred times more human. All the fusion will do is complete the process. You will become all demon, though I don't know what rank you will be. The real cost of the fusion will be your past. No one would know who you were; even if they did they would not recognize you. But you could always use a henge if you don't like what you look like.
"That's fine. I wasn't accepted in Konoha anyway. I don't really care if they never recognize me again. They all saw me as you, a demon. Only Iruka-sensei, Tsunade-baa-chan, and Ero-sennin really liked me. The Old Man Hokage did to, but he died." He frowned at that memory. "No one else cared. It would be nice to start over without anyone recognizing me or knowing what I am."
Kyuubi grins evilly; So you accept.
It wasn't a question but Naruto answered anyway. "Of course."
Very well… to do this I will have to teach you a long forgotten and forbidden jutsu. Naruto's ears perked up at the word jutsu. It was forbidden because it turned the human who performed it into a low level demon. Or it would merge two entities together. Because I am in you, you are considered a Hanyou, a half-demon.
"So the villagers weren't completely wrong about me." He said angrily.
Brat! Didn't you hear me earlier? You were far more human than you were demon. Stupid ningen. I should have killed more. If you want, you can get revenge later, but for now DON'T INTERUPT ME! Naruto cringed at the volume of the last bit and decided to keep quiet. As I was saying, because you are already a half-demon you will not turn into a normal demon. I am one of the Four Demon Lords, as well as the strongest of the Tailed Lords. Most likely you will take on my titles and powers. We will probably be stronger than I was before I was sealed. Any way, it will be up to you to decide what you want to do with the power. You could pretend to be human and help the little rats. Kyuubi still had no love for most humans. This was only reinforced by what she had seen them do to Naruto. Or… she continued, you could continue what I started and destroy them all. Kyuubi smiled at the memory of all the villagers fleeing from her, screaming in fear.
In our case, this jutsu will do the second stage fusion. It will take our two essences and turn them into one, instead of just giving one of us the others power and control, leaving one weak, useless, and angry. If a normal human did this it would permanently open the Eight Celestial Gates, which would most likely destroy the human's mind and body, one reason why it was forbidden. For us it will just fuse us without any further damage, we will them have sixteen Gates that we can open. That is one thing that this jutsu wont merge, but you will be able to open them easier and get more power from each one.
Your Inner Coils will be completely different as well, meaning that you will have to re-learn how to use your chakra. You will still know all of your jutsu as well as mine; you will just have to re-work how to use them.
"That's fine." Naruto scrunches his eyes up in thought. "How come people didn't use this jutsu if it made them really powerful? Most people that I know wouldn't care that it was forbidden or that it might kill them."
So you CAN think. That is actually a good question. The jutsu is extremely long. It takes three hours to perform, and is very noticeable during the last thirty minuets. It can't be felt but it is easily seen, and everyone knew what it looked like. If anyone was seen doing it they were killed on the spot. No one wanted anyone else to have that much power. Another thing that they could do was stop the sequence. Once you start it you can't stop or you will die.
"I don't know the jutsu. How can you teach it to me if that means that you'd die?"
Kit, you really are an idiot. I'm not going to teach it to you. I'm going to give you the memory/knowledge of how to do it. Demons are born with this knowledge, just in case something like this happens. Kyuubi touches Naruto's forehead with one of her tails.
Naruto's eyes widen; "We BOTH have to do it?"
Yes brat. We both have to do it. That way we fuse. If one of us didn't, one of us would cease to exist, and the fusion would be incomplete, weakened. I wouldn't care if it were you, but I won't take the chance that it could be me. She was still acting like she didn't like the kit. She really knew which would disappear. The one who didn't do the seals would disappear, and she didn't want that to happen to her kit, not again. ((We will get to that later)) I'm doing this so that I can continue to exist, as well as you. We may become one but then both us would still be alive, in a way, even if it is as one being.
"Can we do it here or do I have to do it with my real body?" ((Yes, he knew where he was))
Because you can enter your own mind to talk to me you can do it here.
Both of them; "Let's go!"
Naruto begins with the hand seals while Kyuubi starts the Demon Seals ((Demon version of Hand Seals))
Two hours and thirty minuets later Naruto's body began to glow with an unearthly light. Blue and red chakra poured out from him as all eight of his Celestial Gates and Kyuubi's Demonic Gates are thrown wide open. Most people can't stand more than a minuet with all eight gates open before dying, but because of Kyuubi's healing factor it did relatively little damage. The chakra begins to take the shape of two bodies, one of blue light and the other of red. They were the souls of the demon and the soon to be. The red was the image of the nine-tailed fox, tails swishing behind her as if they had minds of their own, and the other was Naruto, chakra dancing in the air like fire. Both spirits were still doing seals. The body below the spirits flashed once before turning into dust and sinking into the earth.
After another twenty minuets an intricate circle of pure energy formed below the souls. Are you ready kit?
"Of course!" Naruto said giving his famous fox grin.
As the last seals were being formed the circle grew brighter, blotting out the chakra bodies with its brilliance. The last seals: ningen, kitsune, and fusion were formed. ((That means human fox fusion)) From deep within the earth shot the pure energy of the earth's soul as it recognized what was about to happen. It burst through the circle on the ground and shot hundreds of meters into the air. The blue and red chakras were caught up in it as the earth wove them together as one. The kanji for all or the elements were formed on the wall of the pillar of light as well as on the ground around it as they recognized the fusion and lent their help to it. Three helped out more than the others. ((Why will be explained later))
After two minuets of energy pouring out from the very fabric of reality ((Think about it, every element and the earth was helping with this)) the pillar began to shrink in both height and width until it took the form of a body. A small amount of chakra still lingered around for a moment before wrapping around the body and forming nine tails. The moment the tails were formed, the light that had been covering the body exploded, releasing a shockwave that destroyed everything within twenty meters and continued out across the continent. Every living thing felt it, even if it were just as a ripple at the very edges of the land, before it dissipated into nothingness.
The wave reached the center of the continent where He rested. The chakra in it triggered something. The crystal began to pulse, as if it were the heart of a giant. A faint light came from within. He was waking up. The son of the shinigami, lord of death, had been awakened.
A.N: still not as long as I'd like, but it's better than the one page thing that it was before. The shiningami's son won't be a major role. It's pretty much a bonus, but he will be used later in the story, just a little.