A/N: Plot bunny. No longer a one-shot!

Summary: Can you really be so sure that an abused child holding an ancient power is sane? Maybe they should have looked deeper before unleashing him into the world. With his berserker mentality active, the ever-smiling blond jinchuriki known as Uzumaki Naruto turns into a bloodthirsty beast at the sight of danger.


Sanguine

Kakashi sighed to himself as he made himself comfortable on the downstairs chair of Tazuna's house. Team 7 had reached the place relatively quickly, but only after running through three ninja, all of which had had the capability of killing his students.

Well, two of his students. The other one... disturbed him. Could it have possibly been the fox's influence?

No. There had been no foul chakra in the air. It was all on his own. How could the Hokage have misjudged him? The blond was always smiling, always happy. Every insult, sneer, and cold look seemed to bounce off of him. His exterior seemed impervious to the isolation.

Maybe they had overlooked his mental instability. It was as if he was bipolar. Two personalities, one that only appeared when he actively fought. Iruka had mentioned something about it, but the masked jounin had brushed it off as adrenaline and stress during the fight with Mizuki.

Only now did he realize what Iruka was talking about. It made Kakashi sick to his stomach.

How could the happy-go-lucky blond be so... bloodthirsty? So merciless? So... destructive?

A shudder went down Kakashi's spine. The sight of the blond bathed in glistening blood was sure to remain in his memories until he died. Sakura and Tazuna had emptied the contents of their stomach, while Sasuke froze and had to force his muscles to properly move again.

Those two missing-nin from Kirigakure had sprang from their hiding spot and attacked as soon as the escort party had passed their puddle. Kakashi well-aware about their presence the entire time and wanted to see how his students would react. Sakura reacted much like he thought she would.

Sasuke would have reacted... but Naruto's actions made him stop. The blond had rushed forward, hands and fingers outstretched. Using raw strength, the blond tackled and snapped the arm of one of the ninja before violently ripping it off.

The other ninja, stunned at the ferocity of the blood-covered blond, was caught unawares when Naruto tackled him and tore him apart. Tearing a person apart with raw strength was impressive, if not unsettling. Very unsettling. The sight of of freely falling entrails only exacerbated the horrendous scene.

But Naruto had done so and Kakashi had seen enough. The two missing-nin were headed towards Tazuna before Naruto killed them in his brutal fashion.

Tazuna was afraid when they walked back. So was Sakura. Even Kakashi was slightly afraid, although he would never admit it. What kind of a jounin was he if he was afraid of a fresh genin?

But that genin had torn apart two chunin-level ninja without a second thought. Sure, it was part of a mission, but most genin had some sort of conscience. They would usually break down after killing someone for the first time.

Perhaps that was why Naruto's actions had been so disturbing. Rather than enter shock after what he had done, the blond merely washed off the blood at the nearest water source and returned back to his cheerful, optimistic self.

He treated the previous event as if it hadn't happened. Or, perhaps, as if it was a completely normal thing.

Kakashi rubbed the bridge of his nose. The next part could have been much more gruesome. The famed Demon of the Mist, Momochi Zabuza, had appeared. Gato had, predictably enough, hired another missing-nin to take out Tazuna.

That had been messy. Again, the merciless, bloodthirsty personality manifested itself. Zabuza had been amused. Kakashi hadn't been. He had been worried. A jounin-level opponent should never be taken lightly.

And then the clones came. Naruto was seemingly inexhaustible in that manic state, as the clones kept coming to attack Zabuza. The man was much more powerful, but the advantage of numbers eventually began to overwhelm him.

The Demon of the Mist hadn't expected a "baby genin" to attempt to rip his face off. Nonetheless, with so many blond copies attacking him without restraint, Zabuza found himself outgunned when Kakashi joined the fray.

However, before Naruto could kill the missing-nin, another ninja appeared. Naruto tried to attack this one as well before the masked ninja vanished with Zabuza in tow. Then his cheerful persona returned once more.

It should have been different.

A rustle caught Kakashi's attention. Looking up to where the stairs were, he saw Naruto walk down, all vestiges of sleep vanishing from the blond as he sighted Kakashi. The blond flashed his sensei a grin before raiding the fridge.

"Naruto... what are you doing?"

"Getting something to eat. There's no food here and I'm hungry!"

Given what was happening to Wave at the moment, of course there wouldn't be food. "Naruto... are you all right?" For some reason, Kakashi didn't want to directly ask Naruto why he had done what he had done.

Naruto closed the fridge and turned to his sensei. He walked to an adjacent chair and sat down onto it, giving Kakashi a curious look. "What do you mean, sensei?"

Kakashi frowned, eying the blond warily. The previous events did not apply. It was like they weren't even registered in the blond's mind.

Or maybe he just didn't see them as morally wrong.

The creeping, strangled feeling that had settled itself in Kakashi's stomach began to intensify. "Why did you attack the ninja like that?"

Naruto squinted his eyes at Kakashi in the darkness. For a split second, Kakashi could swear they gleamed red. "What are you talking about, sensei? I just wanted to see."

Kakashi blinked, not understanding what his student was talking about. See? See what? The sight of their broken bodies? The expression of horror on everyone's faces? The palpable fear emanating from his teammates?

"See what?"

Naruto giggled childishly. "The colors. They look pretty cool. I saw them when Mizuki-teme tried to attack me a month ago."

The color of blood.

That was what he had wanted to see. But where was this desire when he was cheerful and optimistic, or normal? Maybe the Hokage should have checked twice...

Kakashi took a deep breath before speaking again. "What do you mean by "pretty cool", Naruto?"

This time, Kakashi caught the gleam of red. It lingered a bit longer, but vanished when Kakashi focused on it. Still, no foul chakra began to permeate the air. There was no interference.

"I don't know."

"What?"

"I don't know," Naruto repeated. This time, the eyes did not gleam. Or maybe it was so subtle that Kakashi didn't catch it.

He didn't particularly like the latter thought.

"Well... be careful, Naruto. Killing is much more traumatic then you think." Perhaps for the people that witnessed Naruto tearing his enemies apart...

Naruto nodded, gave his sensei an unnerving grin, and then left. Before he completely faded from view, he turned to Kakashi and smiled maniacally. This time, Kakashi caught the slit, red pupils shining in the darkness.

"What can I say? The color of blood describes me perfectly..."


Well, that's it. It was a plot bunny that I needed to get rid of. Fun-fact: Sanguine is a blood-red color, but it has an alternate definition: cheerfully optimistic. Simply make Naruto's berserker button more bloodthirsty and the term describes him perfectly.