A/N: This is an idea I've been toying with for a while now and finally decided to actually write it up after being encouraged by the positive reception my other story 'The Wild Fox of Beacon' had, since the main reason it never got written was because I didn't think my writing would be any good. This story is also part of the reason Chapter 3 of that story took so long to get written up. As per the summary, it will feature a Naruto that uses the Chimera Technique that is featured in the third Naruto Shippuden movie 'Inheritors of the Will of Fire' where Hiruko is the antagonist.

However, unlike the handful of other stories I've come across where he uses the technique, he's not going to instantly master it as soon as he finds it and is instead going to have to put in a good deal of effort to get the results he wants. Also, the reason he's listed as 'Grey' in the summary is that, whilst he's definitely not a good person (he's willing to experiment on animals and people just to make himself stronger), I don't really consider him to be outright evil either since he doesn't have any desire to see Konoha burn (or anything else similar) but instead simply wants to become strong enough to protect himself, even if the way he's going about it can be seen as very immoral. If that's not the correct usage of the term 'grey' then feel free to let me know since I'm not too sure on the exact differences between 'Grey', 'Dark' etc. when talking about characters.

IMPORTANT: I'm going to warn everybody now that this story will contain scenes of biological experimentation (both with animals and humans) in the form of practising the Chimera Technique, as well as violence (it's a series about ninja), some minor non-sexual nudity and probably some strong language as well at some point. If you don't like reading that sort of stuff, then this story is probably not going to be for you. It's rated M for a reason.

Disclaimer: I don't own Naruto, it belongs to Masashi Kishimoto.

Chapter 1: The Discovery

Running down the street as fast as his legs could carry him, eight-year-old Naruto Uzumaki risked a glance over his shoulder and saw that his pursuers were still going strong despite a few of them being more than a little intoxicated. The boy wasn't even sure how he had ended up in his current situation, even though it was something that happened far too often for his liking. He had been walking around Konoha trying to kill time for a bit longer until he went home since it was a Saturday afternoon and thus he had no lessons at the academy and, due to his lack of attention to his surroundings, had bumped into someone hard enough to knock the bottle they were holding out of their hand. Unfortunately, the tipsy man had not appreciated having his bottle of alcohol smashed and, once he got a good look at the one responsible, he had started shouting all sorts of obscenities before giving chase. For some reason, the child's chaser's racket had led to several other people joining in as soon as they had seen him, resulting in the dozen or so strong crowd that was trying, and somehow failing, to catch him.

Sadly, the ANBU operatives that were in charge of monitoring that area of the village were unable to assist the young blond as they had all been called in to quell a riot that had broken out after the group had passed by a small club where a party was being held and had knocked over several of the guests, a couple of whom had been injured enough to require a trip to the hospital. This meant that Naruto had to keep running in the hope that he could lose his assailants or that they would eventually give up. Unfortunately for him, the group's inability to catch an eight-year-old child was frustrating them and it soon became a matter of pride that kept them going, meaning that they had absolutely no plans to give up.

Seeing that his followers were in no hurry to quit, Naruto decided to do something that he, along with the rest of his class, had been warned not to do by his teacher at the academy; that something being channelling chakra through his body to try and increase his speed. The reason that the students had been told not to try it was that they had only covered the basics of chakra usage the previous week after the teachers had made sure that each and every student was capable of accessing their chakra. The rest of the time at the academy had been spent covering things that Naruto considered to be completely useless for a shinobi, not to mention immensely boring, such as the history of the village and the basics of how chakra was formed in the body. The teachers were not planning on teaching anything specific about actual chakra use for at least another month or two and every student was explicitly told not to try using their chakra for anything since they didn't know enough to do it safely and could easily hurt themselves if they did something wrong.

As the scared child tried to focus on the energy inside his body, something that was extremely difficult for him to do whilst moving given how little practice he had, a small rock sailed past his head, indicating that at least one of his pursuers was getting fed up of simply chasing him. After a few false starts, one of which had almost made him trip, Naruto felt the strange warmth of his chakra as it started to spread through his body. He quickly sent it down into his legs and was soon rewarded with a significant increase in his running speed that was accompanied by a slight feeling of discomfort in his calf and thigh muscles. After a good ten minutes of running, during which time the crowd chasing him had more than doubled in size and the discomfort in his legs had turned into full-blown pain, another larger, and sharper, rock struck the blond in the back of the head, disorientating him and causing his vision to blur slightly as he felt a thin trail of blood flow down the back of his neck.

Due to the pain in his head destroying his concentration, the chakra that was being channelled through Naruto's legs was stopped and he soon slowed down due to a combination of the lack of enhancement, the pain said enhancement had been causing whilst active and the pulsing anguish caused by his recent injury. The blond knew that unless he did something, the people chasing him would soon catch up and so he ducked down into a side alley, idly noticing that he had absolutely no idea where in the village he actually was.

Even after turning into the alley, the Uzumaki did not stop as he was sure that the crowd had to have seen him and wouldn't simply carry on past. However, the alley itself was quite bare, only containing a few trash cans and a couple of random cardboard boxes. Fortunately, the blond also noticed a single manhole cover partially hidden by some rubbish near the far end of the alley and was soon trying to lift it enough for him to squeeze under. The circle of metal was too heavy for the child to lift, even with chakra being sent into his arms, and based on what he could hear the crowd had almost reached the alley's entrance.

Luckily, through sheer dumb chance, a sliver of chakra brushed against a small engraving at the edge of the grate and the whole thing swung up like a trap door. This unexpected action caused the unbalanced child to fall into the recently opened hole in the ground with a yelp just as the manhole cover lowered itself back into place, the motion causing a bag of rubbish to fall from the heap and covering the metal disc from view. It was just in time, as the group of villagers who had been chasing him had just ran into the alley after hearing his voice and were now looking around in confusion at the absence of their target.

Dazed from his fall, Naruto groggily climbed to his feet and looked around. It did not do him much good, though, since wherever he was, it was pitch-black due to a complete lack of light sources. After a few minutes of fumbling along the wall, which was further away than he thought it would be, he eventually found a light switch and clicked it on. The bulbs overhead flickered for almost a minute, showing that it had been a very long time since they were last used, before they finally lit up, illuminating the room.

The area was bigger than the blond expected it to be, especially since it was under the village. A brief glance upwards confirmed that the room was taller than what would be found in most houses and it made him wonder exactly how he had endured the fall with only a few bruises and a headache; the rock that had struck his head had done more damage as he remembered the feeling of blood sliding down his neck. At that, Naruto wiped his hand against his neck and felt that the trickle of blood was already drying and the injury to his head had already disappeared. However, all thoughts about his body's apparent durability disappeared as the child took a proper look around. There were numerous cobwebbed shelves lining most of the walls, some filled with books and scrolls whilst others held glass tanks of all sizes. There were also a couple of doors, suggesting that the place was even bigger and making the blond wonder how nobody seemed to know about it. The tanks were full of a pale green liquid and, upon closer inspection of one, Naruto recoiled back in shock.

The tank, which looked large enough to hold something the size of a small child, contained the freakiest skeleton he had ever seen, which admittedly wasn't too difficult since it was the first one he had seen outside a book. It vaguely resembled a dog of some sort but instead of back legs and a short tail, there was a long skeletal tail trailing out that made him think of a snake. The weirdest thing was that it didn't look like someone had just taken two incomplete skeletons and tied them together or something but rather the two parts were joined together in exactly the same way as any other two bones, suggesting that it had once been an actual living creature. That train of thought was confirmed when he looked at the tank next to it which held a dead creature that bore the upper half of a dog and the long coiled tail of a snake and the flesh where the two animals met was a smooth join, though the sight of fur suddenly giving way to scales was more than a little unusual.

All of the other containers had similar contents, either a fusion of two or occasionally more different animals or the skeleton of such a creature. As he studied the bizarre beings out of morbid fascination, Naruto could not help but admit that, whilst the creatures were most definitely bizarre and in a few cases disgusting, they were also kind of cool. After looking at the last tank, which held a featherless four-winged bird, the blond turned his attention to the nearby metal desk to see if there was anything else interesting to look at.

The table didn't have much on it, just a couple of books and a few pictures that showed a few more strange animal hybrids, but it did not matter to him once he started reading an open handwritten book. The item seemed to be some kind of journal that had, along with the underground lair he was in and apparently a few others as well, belonged to someone called Hiruko, though he had been unable to make out the surname, and it detailed how said person had tried to create a ninjutsu that would allow for the merging of multiple living beings into a single entity bearing the characteristics of all of the constituent creatures, which explained the animal hybrids filling the tanks. Apparently, Hiruko's overall aim was to be able to merge with one or more Kekkei Genkai-bearing shinobi to gain access to their abilities.

Upon reading that, Naruto couldn't help but picture himself using some of the abilities he had heard of during classes, like the First Hokage's ability to grow huge trees in an instant or the Uchiha clan's Sharingan, though he didn't know much about the latter. If he possessed that sort of power then the villagers wouldn't dare try and hurt him like they had earlier and they would respect him as well; he had heard how revered the First Hokage was and everybody seemed to admire the Uchiha and Hyuga clans. Admittedly, he wasn't all that bothered about the respect thing since he was much more interested in getting strong enough to protect himself from the villagers that kept trying to hurt him but he guessed it couldn't hurt.

The eight-year-old was about to dismiss the fantasy and carry on exploring when he realised that he might actually be able to do it. The journal contained all of Hiruko's notes, although the technique had apparently not been completed as the last entry mentioned something about Hiruko having to leave in a hurry, so it couldn't be that difficult for him to figure it out. His childish naivety and general lack of understanding of how complicated ninja techniques could be assured him that he would have it sorted within a month or two at most.

Yawning to himself, Naruto flipped a page in the book he was reading as he tried to commit its contents to memory. Despite his initial belief that Hiruko's technique would be easy to get working, it had turned out to be far more complicated that he had first thought. However, the nine-year-old was refusing to give up even though almost ten months had passed since he had first discovered everything; his intense desire to become strong enough to not have to worry about people trying to hurt him proved to be more than enough to keep him going.

Currently, the young Uzumaki was sat on a chair in Hiruko's underground base with his feet resting on the desk and an anatomy book open on his legs. One of the problems that Hiruko had found with his idea was that, to achieve a viable fusion of living beings, all of the body parts would have to be linked together properly. The shinobi had theorised that with a broad enough understanding of the biology of each creature involved it would be possible to ensure that the fusion would occur properly as it was being performed. The downside to this was that, for an absolutely flawless merger, the amount of information that needed to be learnt would take quite a while to memorise. This was the reason that the shinobi had instead tried to come up with a way to bestow some kind of limited intelligence to the technique itself so that it would be able to properly ensure that everything was done correctly.

Unfortunately, based on what was written in the journal, achieving that was incredibly difficult if not outright impossible since such a thing was apparently unheard of. This was why Naruto, instead of spending his time trying to do something like that and probably failing, had instead decided to try and develop the understanding to do everything himself; he also felt that the technique doing everything for him seemed kind of like cheating. To avoid having to learn too much, however, he had limited himself purely to mammalian anatomy since that was what humans were; he would just learn about non-mammal biology if he ever wanted to use the technique on something else.

In addition to his reading, he was also going through Hiruko's notes to see what else needed to be done to actually complete the technique. This was easier than he would have expected since the older shinobi had a habit of writing down numerous theories long before he was at the point to actually test them and had come up with several ways that the technique could be finished. To simplify it as much as possible, the Chimera Technique broke down any being it was used on into individual cells or groups of cells and then rearranged them to get the desired result; in theory, with enough chakra and concentration any number of creatures could be merged at a time. The technique could also, theoretically, be used on any creature, ranging from birds and dogs to worms and fish, without any kind of limitation as long as the creatures were alive since using dead animals would apparently result in something called necrosis, which wasn't a particularly good thing and the images he had seen when looking up the term still made him a little uncomfortable. The problem Hiruko had come across was the rearranging of the separated cells since it was this part that required an immense level of knowledge to get everything right otherwise muscle tissue could end up inside bone or nerves could be connected to each other in endless loops, hence why Hiruko had tried to make the technique sentient enough to be able to do that itself.

A glance at the clock on the wall that he had acquired showed Naruto that he would have to be at the academy in a little over six and a half hours for his lessons so the blond placed the book on the desk, after marking his place, and passed through one of the doors behind him. Shortly after he had discovered the base, he had explored it in its entirety to see what else was there. There were four other rooms present in the underground complex aside from the first as well as a pair of long hidden tunnels, one of which led outside and the other connected to a second bigger hideout, though that one had around a dozen rooms, some of which were quite large, and more exits both inside and outside the village.

He had soon converted one room in the first base into a makeshift bedroom so that he would not have to keep going back to his apartment, which was over on the other side of the village, every night to sleep though he did still go there every now and then to keep up appearances since people were bound to get suspicious if he seemed to disappear whenever he wasn't in the academy and couldn't be found anywhere in the village. The second room already had a pair of large metal tables set up as well as a few other things that made Naruto think that it was where Hiruko carried out all of his experiments whilst trying to complete his Chimera Technique. The third room was set up as a basic bathroom, containing nothing more than a bathtub that had been sloppily converted into a makeshift shower due to his preferences, a toilet, a sink and a wall-mounted mirror and the fourth was being used as a storeroom but currently only held a small fridge and a couple of shelves of food.

After double-checking the timer system for the lights to ensure that they would come on at the right time, the child soon collapsed onto the simple bed he had managed to get down there, not even bothering to change into more appropriate sleepwear. Once again, he was happy that, for some reason he simply didn't know, he didn't seem to require the standard amount of sleep a night that others did and could function without any problems on five and a half to six hours. It also seemed that his body required less sleep the older he got as, before he had stumbled across his current residence, he used to sleep for around seven hours a day. He wasn't going to complain about it, though, as it gave him a decent amount of free time to read through everything that Hiruko had left behind. He chose not to read through the notes in public as he seriously doubted that the villagers would be particularly happy if they knew what he was trying to learn since, if he got stronger, they wouldn't be able to hurt him anymore and that was something that they seemed to enjoy. Within ten minutes of his head hitting the pillow, Naruto was asleep, his mind slowly going over his plans for the following day which involved his first actual attempt at using the Chimera Technique.

The young blond arrived at his classroom with ten minutes to spare and immediately took his usual seat in the back corner. His seating choice not only helped his slight paranoia concerning unexpected attacks from behind that had developed over the years but also meant that he didn't have to deal with other people too much since the class wasn't quite at full capacity and typically nobody sat in the seat next to him. Half of the other students were already present and sitting with their friends chatting. Naruto himself didn't have any friends in the class, which was at least in part due to parents telling their children to keep away from him, but he wasn't bothered by it. If he had friends then he would undoubtedly let his guard down around them after a while and he would rather not expose himself like that around people that could easily turn on him at a moment's notice.

The rest of the class slowly trickled in over the next few minutes, soon followed by the two teachers, Iruka Umino and Mizuki Baikokudo, who appeared just a few minutes before the lesson was due to start. Just as Iruka was about to call out the register to note who was present and who was absent, the classroom door was slammed open by a pair of girls who both proceeded to shove each other out of the way to try and get into the room first. Both of the girls had shoulder-length hair, though one had blonde hair and the other bright pink. Naruto didn't really know anything about the pink-haired girl, he wasn't even sure what her name was, other than that she was from a civilian family and was the first in her line to try and become a ninja. On the other hand, Naruto knew that the blonde was a member of Konoha's mind-walking Yamanaka clan by the name of Ino.

The only reason he even knew that much was because he had done a little bit of research into the various shinobi clans that resided in the village to see what sort of abilities he might be able to acquire with the Chimera Technique once he mastered it. Unfortunately, his research hadn't proved to be all that helpful since he had found out that the unique abilities each clan displayed were almost always secret techniques and not something inherited. That meant that their abilities were all taught and so the Chimera Technique would be useless in acquiring them; he would have to find a member of the clan willing to teach him the techniques if he actually wanted them. The only clans in the entire village that actually had inheritable abilities were the Hyuga clan, who possessed the Byakugan, and the Uchiha clan, who had the Sharingan.

After a couple of minutes of the girls' non-stop bickering about who entered the room first and thus who would be able to sit next to the object of their shared affection Sasuke Uchiha, Iruka got fed up and shouted at both of them to sit down, using what seemed to be a genjutsu to make his head appear much larger than it was. The scare tactic worked well as the pair of girls scurried to the two nearest seats they could find, the blonde succeeding in claiming the seat next to Sasuke and sticking her tongue out at the pink-haired girl in victory as soon as Iruka's back was turned.

Honestly, Naruto didn't know why both girls were so interested in the boy, let alone pretty much every other girl in the class as well. All he knew was that, since the massacre of the entire Uchiha clan a few months ago, Sasuke had gone from the polite and kind-hearted boy he used to be to the power-hungry and somewhat arrogant person he was now. Whilst Naruto could appreciate the other boy's desire for power he found the reason, to kill his older brother Itachi who had been the one to carry out the mass killing, to be a bit pointless. After all, why spend so much time acquiring power just to kill one person? Regardless of that, the blond still kept an eye on the Uchiha as he was the only potential source of a Sharingan in the whole village if he ever decided he wanted it.

Despite the interruption at the start, something that was unfortunately a very regular occurrence, the rest of the morning was quite boring and Naruto ended up focusing more on the different bits of information he would need for his experiment later than the actual lessons. Once lunchtime rolled around, the blond simply slipped out of the academy and made his way to a nearby ramen stand for his meal. None of the other students ever sat with him at lunch, mainly due to the words of their parents but also partly because the young Uzumaki was simply quite boring to be around. He never showed off in any lesson, always kept to himself and generally didn't stand out in any way other than being a little cold to others. That was something he was doing deliberately since he had learnt relatively early on that if he received any attention it would almost certainly be negative and quite possibly painful as well.

The afternoons consisted of the more practical lessons taught at the academy, namely ninjutsu and taijutsu practice. The class had spent several months going over the basics of chakra control and, just over a month ago, the teachers had finally stated that their control was sufficient to start learning the three basic techniques that the academy taught to all students; namely clones, transformations and substitution. Naruto had discovered fairly early on that he seemed to have considerably more chakra than the rest of the students for some reason, meaning that he had to do even more chakra control exercises to get his own control up to the same level as the others, something that he had done in the evenings along with his reading, and had even gone further by raiding the academy's small library one evening for additional exercises, such as surface-walking, as he figured that the better his control the more effectively he would be able to utilise the Chimera Technique. All three of the academy's E-rank techniques had been covered together and each afternoon they would all either practice one of them or work on taijutsu with the teachers helping out by giving suggestions to those who needed them or asked for them.

The technique that was being practised that afternoon was the clone technique and it was the only one of the three that the blond was having absolutely no success with. After a great deal of practise, he had been able to generate the illusionary form required by the Transformation Technique but was only able to maintain it for a second or two before it dissipated. He had also recently started having success with the Substitution Technique but his range was terrible and it took so long for him to actually make the swap that it was currently useless. On the other hand, the Clone Technique just seemed to refuse to work for him at all, something that he suspected may have been due to his larger than normal chakra reserves and lack of comparable control.

His taijutsu was not all that bad either, though there were many in the class that were better than him at it. Since he spent most of his time out of the academy either reading or practising ninjutsu to try and build his control, his taijutsu training generally only occurred at the academy. Naruto was currently toying with the idea of a taijutsu style built around utilising knowledge of the opponent's anatomy and exploiting their weak points since that information was required anyway for the Chimera Technique but his investigations in the academy library had not been much use and, as an academy student, he did not have access to the more well-guarded shinobi library. He also couldn't build such a taijutsu style from scratch himself since he had absolutely no idea how he would go about doing it, so instead he focused on the basic style that was taught at the academy with the intent of looking through the shinobi library when he could get inside without any problems.

Eventually, the academy finished for the day and Naruto made his way back to his home, a term that he had started thinking of the underground base as a few months after he had found it and effectively moved in. Once he had arrived and eaten a little, the blond made his way to the 'experimentation room' as he had dubbed the room with the two large metal tables and other miscellaneous items. One of the tables was still empty but the other held a pair of glass tanks that he had found lying around. One of the tanks contained a large grey rat that he had found scurrying around his bedroom a few days ago and the other had a bat from one of the tunnels. These were the two animals that he was going to use in his first attempt at the Chimera Technique. Whilst both of them had been found mainly due to chance, he had chosen to use them since they were both small mammals and, as such, should be simpler to merge than other creatures that he could find like a cat or bird, especially since he hadn't covered anything concerning the particulars of avian physiology.

Picking up a small metal canister from between the tanks, Naruto placed one end against the air holes in the lid of the tank and twisted the other, causing a cloud of dark gas to descend onto the rat underneath. He repeated the same process with the bat and watched as both animals were soon asleep. The item was something else that had been left when the base was abandoned and it contained a sedative that could be sprayed instead of injected like most. Unfortunately, the tube he was holding was one of only three that he had found and so he had to be careful not to use it all up too quickly. The blond knew that he would eventually have to restock but hopefully that wouldn't happen too soon. He briefly considered the idea of making his own gases, which would be helpful as him buying sedatives would certainly draw attention, and he made a mental note to look into it further at a later time to see if such a thing was worthwhile.

Naruto pulled on a pair of gloves just to be on the safe side and lifted the sleeping rat out of its tank, placing it on the empty table. He put the bat right next to it and made his way through the hand seals that would activate the Chimera Technique, before placing a palm on each of the small animals. After a couple of minutes and a significant drain of his chakra, he thought that the technique had failed and was about to remove his hands when a thin trickle of some strange blue liquid started leak out from under his palm and cover the bat. After a few seconds, the liquid was flowing quicker, though he still wasn't sure exactly where it came from, and both the rat and the bat were covered by thick puddles that quickly joined into a single mass. The unusual liquid then tried to work its way up Naruto's own arms, causing him to panic before he remembered that the technique's nature was to affect everything it could unless it was controlled. The blond then quickly started focusing on making the goo stop covering him and only go for the two animals on the table.

After a few minutes of the liquid slowly but surely making its way up to his elbows, it eventually stopped before receding again. As it did so, Naruto experienced the strange feeling of holding something as it crumbled before he worked out that it was the blue gunk breaking down the bodies of the rat and the bat. As soon as he had that realisation, he quickly closed his eyes and began concentrating on everything he knew of the anatomies of rats and bats and how he imagined they would fit together. He made sure to be as detailed as possible, thinking about things like internal organs and skeletal structures and not just the outward appearance of both animals. As he did, he was again struck by a strange feeling but this time it was of the crumbling object slowly pulling itself back together. The sensation persisted for what felt like an eternity, almost distracting Naruto as he tried to maintain his mental visualisation, until it suddenly disappeared. The sudden change was so surprising that the boy opened his eyes and looked at the pile of blue slime on the table.

The mass was notably smaller than it was before and he was sure he could feel something moving inside. Realising that his test run was complete, he tried to work out how to get rid of the goo before it started to shrink of its own accord back towards his palms. As the puddle slowly receded, Naruto watched with bated breath as the results of his experiment were slowly revealed. A delicate-looking bat wing was the first thing to be uncovered, closely followed by the tip of a wormlike tail. Eventually, the liquid disappeared completely, again making him wonder exactly where it came from, revealing his creation in its entirety. It looked more or less like a large rat with a pair of bat wings emerging from its shoulder blades, exactly as he had pictured it, but the wings were completely still and the rest of being didn't look particularly healthy either. Its front legs seemed underdeveloped when compared to its back ones and they struggled to move around at all. The rear limbs were a bit better as they were actually pushing the hybrid forwards slightly but, based on the laboured breathing, it wasn't an easy thing for it to do. The creature's deformed-looking mouth was wide open as it gulped in as much air as it could but Naruto could tell that it wouldn't last long. He was proven right barely ten seconds later when the winged rodent gave one final wheezing breath before becoming completely still as its life came to an end.

As he picked up his ill-fated creation and placed it in one of the tanks for future study, the blond realised that, despite not living for very long, he had actually succeeded in merging the two animals. That meant that the technique itself was working at least to a degree and it was probably due to his own lack of understanding or chakra control, or both, that he had not been entirely successful. Closing the lid on the tank, he carried it into the container- and book-filled room that he spent most of his time in and, after putting it on a shelf, sat down at the desk. The blond then pulled out his own journal that documented all of his progress and wrote down everything he could about his recent experiment, making sure to cover everything in immense detail, as well as a brief note about looking into making his own sedatives and anything else he may need.

All in all, whilst it was most definitely a step in the right direction, it would take a long time, as well as huge amounts of effort, for him to reach his overall goal of Kekkei Genkai assimilation.

A/N: Not really much else to say here. The next chapter should get posted next weekend and there will be a three year timeskip between this one and that one, with chapter 2 starting off a week before the graduation exams.