Toxicity
By: Hitokiri Musei
Rated: T

Summary: On a simple scouting mission Naruto and Sasuke encounter something extra, and Naruto is forced to care for a poisoned and ailing Sasuke. Deep friendship NaruSasu.

As a warning now, it may end up being yaoi later on, I don't know yet. It depends on where the fic goes. Until it changes, I couldn't tell you. Just know that the two are good friends, like they should have been in the series.

Disclaimer: I do not own Naruto, never have, never will. Sadness.

A/N: Sasuke never went to Sound in this story, so I suppose it is a little AU. I'm going along the lines of Naruto managed to get him back at the battle at the Valley of the End, which I will probably discuss later in the story. All three are roughly 17, and jounin.

A/N 2: All information about poisons obtained from wikipedia. All information about jutsus and various Naruto information obtained from Narutopedia, a wikia.

Chapter 1

"Come on… Come on!"

The blond pushed himself faster, trying to almost fly through the trees as he hurried back to his village, his breath fast and hard. The body against his chest was growing still and he jolted the figure sharply.

"Come on, stay awake, teme!"

Dull black eyes slowly traveled up to look at him, a slow blink covering them after a moment. The pale hand that was entwined in his jacket tightened for a moment, and then began to loosen once more.

Naruto let out a cry. "Damnit Sasuke, stay awake!"

Sasuke's head drooped again, his cheek lying against the orange clothed shoulder. "S'rry…" he murmured, and then his eyelids dropped, his fingers falling from the jacket.

Naruto braked suddenly, stopping on a tree branch. Sasuke's body had fallen limp in his grasp, the dark head falling back on a boneless neck. The blond felt panic flare through him. "Sasuke?"

Nothing.

Naruto shook the other roughly, fearfully. "Don't do this to me Sasuke, open your eyes!"

There was no response. Naruto's heart skipped a few beats, nearly stopping as he looked down at Sasuke's pale, and yet flushed, face. The Uchiha's face was completely relaxed, something that was almost never seen.

"No… No!"

Naruto started moving again, pouring on more and more speed as he leapt through the branches. 'Hold on, Sasuke! Please!'

(1 month earlier)

"I can't believe her… stupid baa-chan… sending me out here with that teme…"

Naruto sent a glare to his left, where Sasuke Uchiha was leaping through the trees after him, onyx eyes focused straight ahead, face calm and composed, mask firmly in place.

Tsunade had seen fit to send the two out on a simple mission together, only to patrol the borders where there had been a little bit of suspicious activity. Sakura was originally supposed to go with them, but an emergency at the hospital had called her away. Naruto had assured her that whatever the problem, he and Sasuke would be able to handle it.

Certainly, with both of them at the level of jounin, there would be no problems. Sasuke himself could probably take on an entire battalion and still come out relatively unscathed. Naruto would probably be able to as well, though he, as a bit more of a berserker fighter, would no doubt be a little scarred up.

Naruto sighed slightly, glancing back in front of him as he leapt through the trees. He and Sasuke were actually on better terms now; it wasn't like it had been in their childhood. A bitter rivalry had turned to toleration, and slowly to friendship. Their bond had not been solidified until sometime after the Valley of the End incident, but now Sasuke was someone that Naruto was proud to call his best friend.

The blond glanced over at his companion, looking him over silently. Sasuke had grown quite a bit, reaching 5'7 not long after the age of 16. While Sasuke had reached his full height faster than his two teammates, he had stayed at that size, and Naruto and Sakura had surpassed him. Sakura was only an inch taller than the Uchiha, but Naruto was the tallest of the group, standing at 5'11.

Sasuke had remained rather petite, even throughout his years as an elite ninja. He was slender and lightly muscled, though he still seemed rather feminine and, in a way, even a little bit delicate. Even so, he was a powerful and formidable ninja, and his Sharingan made him even more of a challenge.

Naruto himself was quite different. In the five years since his fight with Sasuke at the Valley of the End, he had grown and changed in mind and body. He was more mature now, his mind sharpened into that of a quick thinking and talented ninja. His shoulders had broadened, and his natural sun-kissed tan had remained. While he still liked to fool around and have fun, he now knew when to mess around and when to be serious.

"Naruto."

The soft voice startled the blond out of his thoughts and his blue eyes instantly swiveled to the source of the call, his eyes colliding with onyx orbs. Sasuke's eyes narrowed and flickered ahead of them, signaling that the dark-haired ninja had sensed someone's presence.

Naruto nodded slightly, turning his gaze forward and then sniffing the air lightly. Over the years his connection to Kyuubi had almost strengthened, and now he could use the fox's senses at will. His heightened sense of smell was almost as powerful as the Inuzuka clan's, and he found that he could easily track and locate people around him.

Sure enough, the scent came to him and he could tell that there were at least three people just ahead of them. Naruto instantly stopped, his eyes darkening to a light shade of lavender as the Kyuubi's power flowed through him, giving him the sharp senses of the fox. His ears could now pick up any conversation, or movement, if the ninja in front of him did either.

Sasuke moved close to his side, placing a pale hand on Naruto's shoulder. The blond turned to look at his companion; Sasuke's eyes were Sharingan red, the black tomoes spinning slowly, responding to Sasuke's emotions.

Naruto had no time to do much; the ninja in front of them must have realized that they had been found, as they started moving closer at an alarming pace. Naruto's upper lip rose, revealing a sharpened canine as a soft growl escaped his throat. Sasuke's eyes narrowed, his gaze traveling towards where he knew the enemy nin to be.

At that moment a form burst from the trees, flying towards them at a startling pace. Naruto and Sasuke were instantly moving, darting away from the attack and easily dodging the attempt. Naruto's eyes flew towards another ninja as the enemy came at him, his hands coming up to form a familiar sign. "Kage Bunshin no Jutsu!"

Two more Narutos appeared, both taking their tasks of helping to defeat the remaining ninja who had been heading for Sasuke. Even though the dark-haired ninja could have handled him, Naruto didn't want Sasuke to be overwhelmed.

Naruto scanned the ninja as he exchanged basic taijutsu with him, trying to locate some form of identification that would tell him where this ninja came from. There was no visible headband, so he had no idea.

He was brought back to the fight as his opponent performed quick seals. "Kaze no Yaiba!"

Blades of wind moved towards him, knocking him off balance and sending him away from the branch he had been perched on. He quickly righted himself, springing off of a nearby branch and flinging himself back towards his enemy.

"Sensatsu Suishō!"

Naruto yelped as needles of water formed around him and then flew forward. He quickly leapt straight up, managing to escape most harm, even though a few needles embedded themselves in his skin.

A nearby shout pulled him away from his own fight, and he turned to see Sasuke forming quick hand seals. "Katon! Gokaku no Jutsu!"

Fireballs spilled out, burning across the opponent that was quickly dispatching Naruto's clones, leaving him out of the game. Naruto growled softly, not about to be outdone by his friend and rival.

"Kage Bunshin no Jutsu!"

A clone appeared next him, rapidly shaping currents and chakra in his right palm. Naruto grinned, diving for his opponent. "Rasengan!"

The enemy nin had no time to think, Naruto's Rasengan blasted through his midsection and left him falling through the trees, already dead. Naruto turned in time to see the ninja that Sasuke was fighting rear back, getting ready to blow out.

Suspecting a fire type jutsu of some sort, Naruto had no worries. After all, Sasuke was an Uchiha, fire style was his specialty

"Dokugiri!"

Naruto's eyes widened. "No!"

Sasuke was caught right in the face with the deadly cloud of faintly yellowish gas that was nearly colorless. Naruto stared in shock; he remembered it being purple when Shizune had used it. Was this a different type of poison?

Naruto quickly attacked the enemy, trying to disable him without killing him so he could try and find out what type of poison Sasuke had been subjected to. The enemy nin merely smiled wickedly at him, disappearing a moment later using a transportation jutsu.

Naruto felt his heart stop as he looked to Sasuke, who was standing on his branch in a bit of a daze. The blond quickly leapt to his friend's side, landing in front of the Uchiha. "Sasuke?"

The black-haired man blinked slightly, and then frowned. "What Naruto?"

Some sort of relief poured through the taller. "Thank the Fourth… I was worried you'd gotten a big dose of that…"

Sasuke snorted slightly. "Just a little bit, I'm not a dobe like…"

As the Uchiha's voice faded Naruto grew worried. "Sasuke?"

There was no response, and then Sasuke's body crumpled like a rag doll, hitting the branch with a sickening thud.

"SASUKE!"