Confusion.
The absolutely foreign, and familiar feeling of incredible power confounded him. Where had this power come from? Obviously it was His mighty chakra, but it was obviously not his own. Why did he think it was his? Because it was His, of course. He was Kurama! The Greatest of the nine Bijuu! But wasn't he Uzumaki Naruto? He gained this rush of power as He was freed from his prison when he saw his best friend, that brat with those disgusting eyes, jump in front of the needles destined for His heart. He saved His life, as he should have. The child was a mere human while He was a Tailed Beast, of course they should worship and sacrifice themselves for... but wasn't that wrong? Wasn't it wrong for him to spit on the memory of his closest friend? the only one who could understand him? Of course not, those pathetic humans should learn their place! HE was the only one that mattered anymore. After this world has withered to dust He would remain. But did he want that? What was the point of His continued existence if he had no reason to live? With a start, He realized that he was still in the midst of battle.
"I wish I did not have to kill him. He was a noble shinobi." said the Ice child. Narut-Kura-NARUTO looked over at the one called Sasuke, his limp and unmoving form stoking His rage at the Cold girl. He looked at her with bright violet eyes. Now was not the time for thinking, now was the time for killing... fighting.
Without warning, deep purple chakra blasted from his body, encasing him in a shroud of energy with three tails floating behind him.
"Hmm, this is too much stress for this body." he stated aloud before two of the tails disappeared into thin air. Then he also vanished.
Haku had mere seconds to contemplate what she was seeing before Naruto vanished. A split second later her body erupted in pain. She tumbled across the ground as she struggled to breathe.
"You are lucky," Naruto said, "I want to kill you, but I don't want to do something like that."
Haku stood shakily and, in her dazed state, struggled to make sense of a situation that would have confused her normally, "What are you? You are obviously not Naruto-kun. You look and sound completely different."
"I will be Naruto for now, until I can be both me and Me." he said, confusing her further. She saw the violet tail waving behind him and gasped. He was a Jinchuuriki! She had to get Zabuza, they needed to retreat.
Just then, the mist cleared to show that Kakashi and Zabuza had stopped fighting each other and were facing towards a small army of bandits, led by a short man in a suit.
Naruto calmly walked next to Kakashi, whose eyes widened he saw the cloak surrounding the boy.
"Naruto?" he asked apprehensively, "Are you okay?"
"This one is very confused, but questions can be answered after the killing." said the boy. Kakashi was extremely worried now, and opened his mouth to say something, but was interrupted by the short man shouting.
"How disappointing, Zabuza. You couldn't even kill a small team of brats. I guess that means you're not getting paid after all." Gato said with a smirk, "Alright boys! Whoever brings me a head keeps the bounty! Show them why-" he was cut off when a massive feeling of oppression weighed down on everyone there. Gato looked at the boy with the orange hair. He saw His eyes, and that was his mistake.
Gato clutched at his heart at it erupted in pain. He barely noticed his little army dispersing and fleeing behind him. He collapsed to the ground weakly, trembling in fear and pain. One pulse made him clench his eyes shut. When he opened them he saw the monster boy standing over his supine form, a translucent tail poised above the short man's chest. Then the world ceased to exist for him as pain was all he knew, then nothing.
Naruto removed His tail from the weakling's chest, and turned back to his teacher and the demon-man. He walked over and stood in front of them, noticing their tense postures and fearful expressions. He was confused, "Kakashi-sensei, why are you looking at me like that? You as well demon-Zabuza? The one giving you money is dead, so you have no reason to fight-kill us?" he phrased the last part like a question even though it seemed to be a statement.
"Naruto, it's over, you can calm down now." said Kakashi calmly.
"Calm? I am calm. You are the not-calm one." Naruto stated with confusion, before his face showed realization, "Oh, you mean My chakra. It makes you fear. Okay."
The chakra cloak surrounding him disappeared and he turned back to them, "Is this bett...er..."
Then his body betrayed him, as he fell into unconsciousness.
Okay, so I know this first chapter is confusing. That is its' purpose.
The main idea for this story is a simple malfunction in the seal that bound Naruto's soul to Kurama's, resulting in a fusion of their personalities and chakra.
This is an idea that most of you have probably read about at some point, but I wanted to do it in my own way. Also an amusing fact, this idea was actually spawned by the Gem Fusions from Steven universe.
Rest assured, there will be nothing from that show actually placed in here, but I liked the idea of the fusion. Let me know what you think, I am writing this as relief because I'm an ADHD kid and I can't focus on one project at a time.
The cover image is what Naruto/Kurama in this story looks like, and is an image from the internet I was unable to source. It was originally just Naruto with Kurama's eyes, but I edited it to suit my own purposes.