There's always a distinct difference between what is said about something and living said event. Nathaniel was experiencing how valid such a saying was from the unique perceptive of his mother's womb. You may write a thesis about a baby's growth process, from when it's an embryo to the moment he is born, yet nothing would compare to being aware of your surroundings while your body is still shaping itself.
The first thing Nathaniel did after acknowledging his situation was, of course, to freak out. Staying indeterminately in nothingness might have been a weird experience, but it wasn't anything to compare. Before, Nate didn't have any stimulus from outside. He didn't even get the feeling of possessing a body. The only thing that kept him sane was being able to preview his life repeatedly. Even then, he wasn't sure how come he still felt sane.
Whereas being able to feel his body and what surrounded it and hearing noises that didn't make sense was a very foreign and unsettling experience. Nathaniel knew why things were the way they were. It didn't help him to accept his circumstances. Or at least it took him a while before he could calm down.
One of the reasons for this shift was from being able to feel his mother's presence somehow, her aura. To have this impression of safety and love, this promise that he didn't have to worry, that he wasn't alone. Starting from this moment, Nathaniel could think about how to wait for his eventual birth.
The first thing that came to his mind was to focus on his senses and determine where he was. He might be in a different country, implying he couldn't understand the language used. Until now, the noises Nathaniel could hear didn't make sense. Yet he couldn't say if it was because of his circumstances that the words were distorted or if the language his parents used was foreign to him. There were also a lot of other noises that didn't come from someone talking, which didn't help his goal. Should he understand outside conversations, Nathaniel could determine where and when he was reborn. Those two things were the easiest and more realistic challenges Nathaniel put upon himself.
The second thing Nathaniel thought of doing came from his desire to live a somewhat extraordinary life. He might have died past a century old. Despite that, with the time spent between his death and reincarnation, he could relate just as easily to his childhood fantasies as to his time grounded in reality. From those fantasies came the possibility of harnessing the power of his mind. Or that of his soul. His mind, as a person's consciousness such as it exists thanks to an individual's brain, was somewhat diminished considering his current ungrown body.
It was an intriguing thought. Nathaniel couldn't yet determine how many days or weeks had passed since his mother got pregnant. But from how little he could move, he knew his body's brain had, at best, just started being formed. Since the brain was proven to be the core of a being's reasoning and a memory's storage, Nathaniel's theory was that the soul was like a copy of someone. All of one's experiences during their life were imprinted upon their soul, from how their body grew to their memories and cognitive capabilities. Why it mattered in this situation depended on Nathaniel's hope for some psychic abilities.
Indeed, without knowing where such an ability came from, there wasn't any possibility to control it. Despite how irrational the hope for the supernatural might be, Nathaniel was confident he would succeed—bolstered by the weirdness of his situation and some other senses he couldn't pinpoint. An intuition that the awareness he had despite his present state was due to his soul, which had more potential than most. His reincarnation might be one of the reasons for that, of course, yet it didn't explain his unfounded belief. He knew dallying on this strange sense would amount to nothing, instead preferring to focus on what mattered presently.
To reach inside of himself for this supernatural power, Nathaniel thought about all the texts and works which made mention of meditation, inner peace, and similar subjects. It took him a while to filter through the valuable bits of data he had perused during his life. But he eventually managed to use his loose knowledge to make some progress. The elation Nathaniel felt upon his first moment of success - around ten days later - was cut short by realizing where he found himself.
Indeed, he was back to this weird space of nothingness, where his only companions were his memories shifting perpetually before him. Only the faint presence of what he called his mother's aura prevented Nathaniel from freaking out once more. Then came the awareness of what this place probably was. His soulscape. It felt apparent now that he thought about it. While knowing this fact did a lot to assuage Nathaniel's worries, he still wanted to make sure he could quickly shift his awareness from his soulscape to the outside and vice versa.
Once he had done that, Nathaniel focused on organizing his soulscape, building a foundation for his mind. With him remembering every detail of his life when he was trapped in this place, imagining a zone containing all his memories was relatively fast. His idea was to find himself inside a sphere, with the wall being covered by bookshelves. Shifting the bookshelves would change the memories/books being accessible. On the outside, it would appear as a sphere surrounded by mirrors. Nathaniel had no idea how effective it might be, and he planned on improving his soulscape when it proved necessary. Until then, this version will do. Nathaniel didn't need it to be effective against others. Not yet, at least. What mattered was that it made it easier for him to re-explore his memories any time he wished.
Furthermore, the most important thing was what the proof of having access to his soulscape represented. That the supernatural wasn't out of his reach.
Having access to his soulscape and reorganizing it also became a trigger for awakening his spiritual senses. What it meant for Nathaniel was an awareness of anywhere this sense went, which wasn't far at all, unable to expand past his body. For the reincarnated man, it was already extraordinary. For one, it made it possible to inspect his body condition and become aware of how long he had left until his birth. As it was, Nathaniel guessed that he still had close to seven months until he would breathe his first.
Another benefit of acquiring a spiritual sense was that it granted him the best opportunity to consolidate his knowledge of anatomy. Indeed, the best way to build the groundwork for his future growth was to know his body. Know yourself and know your enemy; you need not fear the result of a hundred battles. The first part was started, at least. He only had to ensure he would remember to learn of his eventual enemies. Otherwise, he would suffer a defeat for every victory. Having the opportunity to get intimately familiar with every aspect of his body would allow Nate to tailor any future training he would do to be the most efficient.
With estimated knowledge of his birth date also came the possibility of planning for the following months. The most crucial objective was to train this new spiritual sense. The first threshold Nathaniel wanted to reach was to extend his mind past his body and his mother's. The second objective was to use his spiritual senses to confirm his environment. Knowing where and when he lives felt significant. Following those two objectives, different choices might be made. One that would stay the same was exploring his spiritual sense's limits and training until it felt as easy and natural as thinking. After that, Nathaniel expected to focus his training differently depending on their household situation.
With a goal set, Nathaniel busied himself with expanding and retracting his supernatural sense. Initially, he couldn't maintain it for a very long time, barely a few minutes. Yet after every rest, the time he could sustain his new ability kept increasing. After a week of constantly studying his body, Nathaniel could maintain his focus for an hour. By that point, he was getting quite familiar with his growing body, getting a refresher on his very brief studies about human anatomy. Most of the things he learned were more complex than anything he knew. His spiritual senses allowed him, among other things, to understand the chemical process of how his body worked. While before, he only had a rough knowledge of how hormones, proteins, vitamins, and other substances might affect someone, now he had a deep understanding of precisely what influence held each of those chemicals. Things that before wholly eluded him.
This was just an example, as Nathaniel kept learning other facets of body growth in the following weeks. What use it had wasn't apparent right now, what with him yet to be able to influence his development. Later, though, it would become quite helpful to ensure he could grow and exploit his potential to the fullest, to ensure his body will be as healthy and in tune with his mind as possible. It would allow him to avoid having any congenital disease or growth defect. Still, it was a work in progress, and there was a difference between knowing about something and having the mean to influence it.
From being able to inspect his body, Nathaniel started expanding his senses outside his body. There was a slight resistance upon bypassing his skin, and he could also feel his ability being somewhat dampened the further from his body he tried to observe. From this hurdle, Nathaniel decided to change his training. Rather than trying to keep his awareness as long as possible, he tried to make one brief pulse, like a sonar. Another method was to shape his spiritual sense as a thread instead of spreading it evenly around him. A week was spent trying each of those methods.
Eventually, Nathaniel discovered that giving a form to his power and guiding it to a fixed location was much more effective as a training tool. However, it was less informative than an even wave of energy. But for what it lacked in scope, it made up with an extended range and a much more flexible application of power. Using his umbilical cord as a bridge to get past his body also proved to prevent the weakening of his senses.
From then on, Nathaniel kept training, spending around a week exploring the diverse ways to make threads of spiritual power. It was also much more effective to read his mother's health accurately. The results, however, were worrying. She was malnourished; her body barely had any fat cells, and her muscles were too thin to be healthy. Her body also lacked many vitamins, worsening her condition. That she was pregnant certainly didn't help, but she was shockingly frail. As her child, Nathaniel could only worry for her and think of ways to help her. At least he could reassure himself by feeling that whenever he felt exhausted from using his psychic abilities, it only came from his soul, with no consequences to his body. If he otherwise had been one of the sources of his mother's weak condition, Nathaniel wasn't sure how he could've coped.
He eventually linked those threads of spiritual power with his mother's senses, mainly her hearing and sight. It allowed him to finally get a picture of what was happening outside. Extending his spiritual sense past his mother's body was impossibly hard.
There wasn't a way to know if he could change anything and improve his mother's life, but at least Nathaniel believed he could better accept it by understanding his living place. Awareness was also the first step to start any change, should it become possible.
What welcomed his sight upon borrowing his mother's senses was baffling. While aware of the existence of different kinds of tribes across the globe, Nathaniel never expected to be reborn in one of them. Being mostly cut off from the world as they were was a very peculiar way of living. At least for someone who used to live in a city with all the technology it entailed, the difference would be unsettling.
The first scene Nathaniel saw was a cluster of huts, mainly made from straw and hay, animals' skin, and sometimes branches. Seldom were made with rocks. All houses were only big enough to host half a dozen persons. From what he could see, Nathaniel guessed that his mother was sitting at the entrance of her hut. Or at least someone's hut. He wondered if she lived with only his father or one or both of their families. She appeared to be weaving straws to make a basket. Around her, there was barely any vegetation, and the few people walking around were only children or women. The tribes-peoples were dressed relatively simply, with pelts for most of them, even if they were well-worked. As for ornaments, most women wore trinkets and jewellery made of bones. All tribes-people also had various drawings painted over their skin in hues of red and black, probably from a mixture of red earth and charcoal or similar tincture.
Later in the evening, Nathaniel felt he might have made a wrong assumption about how far he would get reincarnated from the moment of his death, be it the timeline or the location. It became apparent when groups of men returned to the tribe covered in blood while carrying corpses, both humans and animals. Whereas the men didn't have anything different than the other members of the tribe, safe for their gruesome appearances, the beasts they brought told another story. One specimen, in particular, was distinctly foreign from any beast Nathaniel could recognize. They looked like the monstrous crossing between a prehistoric boar and a rhinoceros. Except their skin looked like black tree bark rather than sheets of leather. Its size was also smaller than a rhinoceros but more significant than a boar, barely reaching a person's waist from what Nathaniel could observe. The group walked through the tribe toward what Nathaniel could guess was the chieftain's lodging. He could briefly see a building taller than the other deeper in the camp. Watching the procession also allowed him to see their weapons—a mix of spears, javelins and clubs. None of them wore bows, although most had slings, which, going by the number of smaller animals the hunters were carrying, might be their most used weapon. All weapons, slings excluded, were made with wood, bones, or stones.
At this point, Nathaniel realized there wasn't any reason for him to get reincarnated in the same world. Or in the same timeline. He started to believe there was just as much chance for him to have ended up in a different world. He could at least infer from the unknown beasts that he wasn't in the same century or millennium as his death. He didn't know if such beasts had existed on the Blue Planet, but if they did, it was at the beginning of human history. However, the humans he could see were Homo Sapiens, at least close enough that their appearance was the same. A straight posture and a small and somewhat round skull. At least compared to any of our human ancestors. Nathaniel had only a brief history lesson on prehistory during middle school, and such details eluded him. What mattered was that he might have been sent to another planet altogether.
Did that change anything about his concern related to his mother's health? More than one could imagine: With how lacking their knowledge was concerning everything, Nathaniel was somewhat confident that he could improve most of their ways of life. They had some part of their life that clearly showed their capabilities, whether their hand-made weapons, clothes, trinkets or tools. The most telling was the presence of wheels, which was quite out of place compared to the rest of their technological advancement. The wheelbarrows and rikshaws, in this context, were a most peculiar sight to Nathaniel. Their tools and weapons ranged from bones to carved stone, wood, or materials probably gathered from beasts. It included atlatl, needles, cooking utensils, ropes and more. Despite being mostly made of leather and woven straw, even the clothes they wore were quite intricately worked. This showed they had the means to improve their lives but only needed some critical points of knowledge and a few essential resources.
There was only one hurdle to Nathaniel's plan to teach his mother anything. If he wanted to be able to impart any knowledge to his mother before his birth, he would need to communicate with her. However, Nathaniel didn't want her to believe she was crazy. Or that a demon took possession of her baby. Or that some evil spirit was haunting her. Or any other troublesome conclusion made upon having her unborn baby grants her knowledge. Being a reincarnated person might be the less believable of those explanations. This meant he had to think of a way to develop his nascent psychic powers to allow for a non-traumatic teaching process.