With one of his main projects finished, Dix decided he would rather study something else instead of perfecting the seal on his body. He had a long-time primary goal he wanted to achieve, which was the acquisition of the Flying Thunder God technique. This is the jutsu he always wanted to learn and use. And not only because it is fancy. FTGT is an incredible jutsu that is both offensive and defensive at the same time. Being able to move faster than anything else gives so much options its just incredible. And its not only a combat jutsu, as it can be used as a utility and simple movement technique because of its extremely convenient properties.
FTGT is not a jutsu that just lets you go really fast. Its actually a reverse-summoning jutsu. The user applies their special formula of the jutsu onto any surface, be it objects or humans. When the user activates the technique that specific formula gets a signal that summons the user to its location. The Second Hokage came up with this jutsu... By the way that man was the real genius, he created many techniques that are looked up to with awe and fear all over the ninja world.
Back on topic, the Second made it and the Fourth, Minato, perfected it. First the formulas would decay over time with which the technique was still utterly bonkers, but Minato managed to make them last forever, even after the user's death, which is just nightmarish. This technique lets the user achieve true instantaneous movement. Also, it can teleport objects or other people that are connected to the user in any way, the user can even send something somewhere without himself going with it, which makes it one of the best utility and defense jutsus of all time. As long as the user's reaction time is better then what the attack requires, the user can send any attack away using this technique.
He absolutely had to get this jutsu, and he was in luck. He already had the support of the Third Hokage, who was safeguarding the jutsu in the forbidden scroll. He was regarded as a genius, and he would be given anything as long as he is loyal to the village. If he were to ask for the jutsu he would probably get it, as there is no downside to that. If he doesn't manage to handle it he just gives back the technique until he grows more, but if he is able to learn and master the technique, then the village would already have a trump card in its hands, even if he can't control the Nine Tailed Beast yet.
To prepare for the technique, after the Eight Gates project he had to focus on learning everything about summoning jutsus, so Squad C, the seal team was converted into the space-time team. Also, he needed something else. Even though Minato was able to use the technique just with his own reaction time and reflexes, Dix wanted to one up that. There was a specific way to upgrade his stats to better use FTGT, and master it to its limits. It is the Sharingan.
If Dix was able to get a pair of those, he would be able to track anything and anyone real-time, his reflexes and reaction time would hit the roof and he could utilize FTGT to its maximum. The question is... how does he get one? And the answer is really easy. The massacre of the Uchiha Clan was yet to happen. That is the one golden opportunity to get his hands on one. Actually many pairs. He wanted to take at least 4 or more to experiment on them and better his own he will implant into himself.
Before and after the massacre its incredibly hard to get a pair of sharingans. Before that night security around that 'technology' is extremely great, and neither the village nor the clan would let anyone take it for their own needs. After the deed its just simply impossible to find sharingans, as every single one of those who had it are dead and are cleaned up by the ANBU. Except for Itachi, who is the one to kill his own clan, Sasuke, his brother he lets go, and 'Madara' that secretly helps Itachi from the shadows. Also Kakashi has a single Sharingan in his left eye, and it would be extremely hard to take it from him, or from any of the aforementioned.
But on that specific night, its as easy as taking candy from a kid. There are only a few selected people that know about this, no more then five, and there are only two that are actually there, Itachi and 'Madara' who are mostly occupied by killing people. If Dix were to enter the premises with his utmost caution, he would be able to snatch a few corpses for sure.
This is why he got a few containers and the special solution to conserve and store these eyes which he could use later.
This operation would be his first real challenge. He would need to give his all, first and foremost to not be detected. He has to go in, extract the cargo then evac. It's not hard, but two of the strongest ninjas alive are there at the same time. He can't afford to be caught. Even though Itachi and 'Madara' are incredible existences, they are acting with the safety in their mind that nobody knows about what they are doing, except for a few people that orchestrated it. They would focus on the actual killing instead of trying to look for something that shouldn't be there.
With these thoughts in mind, he proceeded to plan the operation. He needed the most accurate information about the clan's layout as possible. He wanted to predict Itachi's possible routes, which he knew would end at their own house, plan around it, while also keeping in mind the existence of 'Madara', whose location he doesn't know whatsoever, which meant he needed routes of escapes at all times, no matter where he will be.
It took him a lot of time, and even some money to get his hands on reliable blueprints of all the houses that were built in the Uchiha's district, also the plans for the uniform layout of the district itself. He also tried scouting as much as possible from every angle, looking trough every nook and cranny, getting his hands on every available information. He had to meticulously plan the whole operation down to the last details.
It has been months since he started working on the plan, and when he planned every single step he will take, he finally felt like he will be able to pull it off without any problems. All he had to do was create a small entrance way before the night of incident, which would be at a calculated location, close to the best 4 candidates houses that Dix found. Their eyes suited his needs the best, and they were mostly nobodies, so probably no one noticed if their corpses disappeared. The eyes were already awakened to the 3rd level, while they seemed to lived a happy life without many emotional distress. This would keep their sharingans power a bit low, but also clean of most negative intent that could cause complications at and after the surgery.
The plan is simple and is designed to take the least amount of time possible. After he entered through the hole on the wall that surrounds the Uchiha's district, he would try to discern which route Itachi takes, then when he passed trough the houses he would quickly gather the corpses one-by-one in the same order Itachi went. He would have to stay behind him close enough to not give time for 'Madara' to appear, but also far enough so he isn't detected.
With the plan and the preparations done, now he had to work on the actual ninja way, and practice erasing his presence to the best. He was 6 years old at that time. For the remainder of the time before the incident happens, he decided to use every squads of clones, except Squad C that was learning summoning jutsus and Squad X, the R&D department, to suspend all activities, and he sent them out anywhere and everywhere to practice stealth. He would try to hide away from any random people on the streets, he would try to follow animals as close as possible and he would try to hide away from official ninjas.
First it was really hard. He didn't actually know what he was supposed to do to lower his 'presence'. He read some books, asked experts with the motion of 'trying to become a ninja'. He needed a lot of practice, and he was the best at that. Also the seals he had on his body were extremely useful. Most of the time ninjas try to scan their vicinity for unknown chakra sources, which are usually humans. Every living being leakes chakra to some extent.
Ninjas practice for years to completely stop these leakages, but there is always a tiny bit of crack which is barely noticeable, but still gives away their position. Or simply something unexpected comes up, there is a shift in focus and the ninja is already revealed. On the other hand, Dix had a passive suppressive force that perfectly keeps any leakages closed. This would mean he could concentrate on his physical presence instead of his chakra.
After around 2 years of practice, he felt like he was quite good at it already. Take note, that every day Dix used around a hundred clones for practice, meaning those two years amount to almost 200 years of experience stacked on top of each other. Well obviously its way less then that, and he only practiced this for around 8 hours of a day, but even so, he had worked quite hard on this.
Throughout those two years nothing much happened, the Third kept checking on Dix to see his exploits, but he could never fathom his true achievements. He didn't get new friends, except Yami, the wolf cub was growing very nicely, and was cub no more. He kept training her and she showed great potential as a nin-dog. He also kept his promise to Kurama, and visited him at least once every week ever since their first meeting. Even though Kurama knew everything Dix did, he still kept him updated. He was pretty sure of his success, but he still needed Kurama as a safety-net if it comes to the worst.
The night of the Uchiha's Massacre was crawling ever closer, which would prove the fruits of Dix's hard labor for the last 8 years. This will be his baptism by fire, and he was excited at the prospect.