A solitary adventurer took a few wary steps into the mouth of a strange, dark cavern. When nothing rushed out of the depths of the cavern to attempt to attack him, he reached into the water-proof back pocket of his standard-issue adventuring uniform and pulled out a small scroll, right as the skies behind him began to darken thanks to ominous storm clouds.
The scroll was a cheap thing, a one-time spell-casting device unlike some of the pricier scrolls the adventurer had seen and wished he could afford. It was a single rolled-up piece of paper that when unfurled revealed a sort of spell that any human could use if they had had the right kind of training. Inconveniently as it so happened, Raul Lobos was an H-rank adventurer. So he was not wealthy enough to afford the sort of training it would take to master the "radiance" spell, and as a natural consequence of that, he was forced to rely on scrolls.
The adventurer skillfully unfurled the piece of paper, which was hardly an achievement. Once the paper was unfurled Raul glanced at it. It was covered in arcane sigils that the human could only barely read. He knew that the purpose of the eldritch scribblings was to reduce the mana consumption of the spell he was about to cast to nothing, but glancing at the scroll and seeing the strange, moving letters, was still very strange.
The paper was covered in letters that moved around on the paper of seemingly their own volition. The letters were written in the blood of magically-imbued individuals, wealthy men, and women known as "Imbrites" who could use their own blood as a spell-casting component to boost the effectiveness of spells or to cheapen the mana costs of spells. The word that Raul was looking for was located smack-dab in the middle of the scroll. Once he spotted the word, the adventurer quickly memorized it.
With a grin the adventurer lifted the scroll so that he was holding it high in the air in front of him and readied himself to utter it. Right as he was about to speak he heard the powerful and sometimes deafening sound of thunder behind him, right as it began to rain just outside of the cave.
"Luz!" Raul shouted, grateful to have shelter. When the word, an ancient word for "light", escaped his lips the scroll began to burn and the flames quickly consumed it right as the spell it contained took effect.
Light exploded out of the burning scroll and illuminated the outermost parts of the cavern. Until just now not far beyond where Raul was standing, the outermost section of the cave's mouth, darkness was the only thing that had been visible. Once the spell was cast, a powerful burst of light revealed that the cave was an intimidatingly vast one.
The adventure had cast a spell that illuminated close to one hundred meters of the cavern and yet beyond the spell's range all Raul saw was more darkness instead of a wall as he had hoped to see. Raul sighed, and steeled himself for what he knew could easily become a whole adventure. He wordlessly stepped deeper into the cave, mostly doing so to escape the bit of rain that was threatening to try and soak him if he continued to stay at the edge of his temporary home any longer.
The traveler walked until he was in the middle of the illuminated area and then studied his surroundings further. He was inside of a tunnel that allowed someone to either enter or exit the cavern he had found at the edge of the forest he had been tasked with helping to map. As he sat down he began to make the cave a better shelter for himself.
He opened the main pocket his adventuring uniform possessed and reached into the magical "inventory" space where he kept a number of goods and supplies. As he reached into the magically boosted and protected space he visualized a few branches and an arcane lighter, four items he possessed precisely for situations like this.
Over the course of the next few moments, he steadily pulled out each of the items he had visualized. The branches were precisely what they looked like, three pieces of firewood that he could use to create a fire to warm himself up, and one lighter that was magically enchanted to create a warm flame that didn't use up oxygen or cause gas-related explosions.
The lighter was a seemingly mundane item, but it did have a small marker that hinted at its unusual nature. On the side of the strange item there was an "L" etched onto it. The "L" was actually a reference to the arcano-engineer who created it and was capable of glowing in the dark.
Raul put the firewood together in a small corner of the tunnel. When the three pieces were close together, the adventurer, who was just a few hours from turning 21, grabbed his lighter and set the firewood ablaze with a single click of his magical device. A thin, orange flame began to slowly consume the firewood and also warmed up the small corner of the cavern that Raul had temporarily claimed for himself.
The tiny, orange flame began to warm up the young man. Distantly he heard the sounds of rain continue to pour, and he chuckled to himself.
"What a way to spend the night before I turn 21…" He uttered, slightly annoyed that he might well spend the night here and not in the small room he had been renting for the last month while saving up money to continue traveling.
His voice was a low growl and he felt annoyance surge through him in waves. That said it was quite late in the day already and the sun had set over an hour ago. When he first made his way into the cave he had been able to see some of it through the light of a full moon and his own decent vision but now… Well now seeing anything outside was virtually impossible.
The adventurer stayed in a state of alertness for over an hour, but as he did the rain outside began to intensify. At the storm's most intense moment water began to pool into puddles just inside of the cavern, due to the cavern sloping downward, and also the cave's uneven flooring. Raul had been able to ignore such inconveniences, due to his nimble footwork, but rainwater was not as clever as he was. So rather than pouring into the cave the water was unable to do much more than soak the outermost edge of the cavern.
At some point during the storm, Raul quickly began to feel drowsy. Many adventurers would normally hesitate before going to sleep in a random, seemingly sizable cavern but Raul had a specific trick up his sleeve that allowed him to sleep in caves without fear.
The young man rolled up his left sleeve and placed a hand on the wall behind him. He closed his eyes and wordlessly activated a sort of spell known as a "cantrip", a beginner-level spell he had mastered to the point that it didn't cost him any magical energy to use.
Behind him, the earth groaned and began to move. He kept his hand on the wall until the earth moved in such a way that he began to create a wall. Meters of stone roared and groaned as it moved to close off the open, unexplored area behind the adventurer. It took a few minutes but after patiently waiting long enough so much stone was in the way of anyone behind him that it wasn't really worth trying to break through, at least if the creature was something like a goblin that wasn't suited to breaking through stone but did tend to live in caves.
Once this was done, Raul walked up to an area closer to the cave's exit and repeated what he had just done with one small variation: he left a small window for him to both get air and also for him to peek through tomorrow. All in all, this took a few minutes, and when it was done Raul had constructed a neat little camp for himself.
He studied the completed structure for a few moments before laying down not far from the fire. As he laid down he momentarily thought of his small room again and hoped that he'd be able to sleep in his own bed tomorrow night. He quickly fell asleep and soon after was in the midst of a very odd dream.
On the night leading into his 21 birthday, Raul Medrano dreamed of many things. The first thing he dreamed of was darkness.
The sleeping man's subconscious mind conjured up an "image", if it could be called that, of utter darkness. In the dream itself Raul "awoke" and attempted to make sense of what he was seeing. He "turned", to the best of his abilities anyway, and much to his chagrin could see nothing. Try as he might, for the duration of this particular dream all he saw was an endless ocean of darkness.
During this particular dream, something odd was happening to his body. It was undergoing changes, and not the sort of changes that a parent warned a prepubescent child of, but changes that were both unique to Raul and also far more substantial than any sort of puberty could ever be.
The now 21-year-old adventurer's body was evolving and shedding his humanity. The first sign of this never-before-seen sort of evolution was that his sleeping body began to dramatically glow. Had anyone been around to see the glowing man's form they would have wanted to wake him up, but he was all alone in his impromptu campsite.
As his body began to glow, he spontaneously gained truly remarkable muscles. The adventurer had lived his whole life as a lithe, dexterous type of adventurer but his metamorphosis changed that by granting him the sort of muscles that were most commonly possessed by deities of strength and heroism. And it wasn't just his muscles that were changing either.
While he dreamed of darkness, his mind was forcibly upgraded. His brain was changed on a metaphysical level by forces beyond his comprehension. The first change his mind received was that it was upgraded on a linguistic level. The man gained a new, passive power: the ability to understand and speak any language, as well as with any form of life beyond his fellow humans. Plants, animals, machines, spirits, and even eldritch abominations would soon find that they could understand him and more importantly: that he could understand them.
His mind received other, stranger upgrades as well but his linguistic ability would be the most immediately apparent change of them all. The forces responsible for his change spent the most time modifying his mind and brain, and it was only when they were done with it that they dragged the man's subconscious mind out of the darkness it had conjured for him to dreamily explore.
In the final moments that Raul's mind was entrapped in darkness the first thing he got a chance to see that wasn't darkness was a text box that appeared abruptly in his mind's eye. It was a strange textbox to be sure but a welcome sight compared to the seemingly omnipresent darkness that had flooded his vision for what felt like an eternity.
[Raul Medrano, the time has almost come for you to awaken, and also for you to become who you were meant to be.]
He read it curiously, unsure of what it meant beyond the fact that he was about to wake up from this weird dream. As he studied it, his surroundings began to change.
After being surrounded by darkness in all directions, Raul was abruptly surrounded by the light blue light of a clear, cloudless sky. It was in all honesty equally annoying compared to total darkness, but Raul didn't complain as it was almost welcome compared to being surrounded by what felt like dark nothingness for an unknown amount of time.
It was here that the next textbox appeared before him, or rather that the existing textbox's text was changed. He watched as the first message vanished and was instantly replaced by another, seemingly pre-written message.
[Raul, at the moment your body, mind, and soul, are all changing. Now that you are an adult your soul has reached the point where it can sustain the first fraction of your truest potential, and so your body, mind, and even soul, are being upgraded.]
The message within the text box would have caused Raul's eyes to widen, had that been possible. It was not, since he was dreaming, so instead of that his "face", as it were, remained a perfectly neutral mask. And that was when the textbox changed again.
[You are receiving many upgrades all at once, but the only thing you need to do is imagine your ideal form. Your muscles have already been boosted to their maximum potential, giving you unlimited, raw physical strength but that is the weakest of the upgrades you are receiving. For the sake of speeding this along, please go ahead and visualize your envisionment of your perfect, physical self]
Raul quietly wondered if this strange dream was actually just a dream, but he was a good sport and could play along. Plus, at the very worst, he figured this would serve as motivation for him to work towards becoming his ideal self.
Raul was a tall, lithe sort of man. He had powerful but thin muscles and was skilled at wielding muscles that required dexterous hands. He had tan skin, thanks to his job being an outdoorsy one. And his ideal self was very different from his current self.
Following the strange textbox's instructions, Raul quietly visualized his ideal self. In his mind's eye, he envisioned a powerfully built almost archetypal depiction of masculinity. He was a powerful, overwhelming warrior in this aggrandized envisionment of his future self. He had visible, rippling muscles, was towering over other people, wore powerful armor made of arcane metals, and wielded mighty weapons made of various, eldritch materials.
He spent a few moments idly envisioning that "perfected self" and at first nothing happened. Moments passed and he began to laugh at himself, wondering what he could do to wake up from this strange dream. Almost immediately after he wondered that, the strange textbox changed once more, and a second textbox appeared. And this time he began to feel excited upon beginning to read them.
[Initial preparations complete. As soon as you finish reading these messages you will awaken. The immediate changes have already taken effect. Some of them shall be obvious. Others shall not be. For clarity's sake this is not a 'strange textbox' as you have dubbed it, but a version of 'the System' compatible with higher beings such as yourself.]
[While you were dreaming of darkness 'the System' was performing a diagnostic scan on you and your world for the sake of determining which of your powers and which spirit-type to awaken within you first. It was decided that you would first gain your Grand Adonis powers as those leave you more superhuman than conceptual, and that will allow you to adjust to your inhumanity better. 'The System' will be here to help you gain a greater grasp on your powers and reach a state where you can awaken your next set of powers in the days to come. Congratulations, reality-reshaper. Now, the time has come for you to awaken.]
As soon as Raul finished reading the second message, his actual eyes shot open and he began to laugh. Raul, the reality-reshaper, was now 21 and had just unlocked his first set of superpowers.