"Intermediate-Stage Master Realm…"
The young Arthur Vaughn muttered this, naming his current Existence Realm as he watched several of the Devildom's Knights train from his tower in the Royal Castle.
Apparently, he was already in the fourth Realm on the progression list, thanks to some of the magical power he had absorbed from his mother at birth.
In a time when the average Existence Realm of newborn Devils was declining each year, being an Intermediate-Stage Master was considered quite high.
'Well, I'm not even a Devil, though,' he thought with a sigh, recalling when three-year-old him had first learned about the prophecies that had spread before his birth.
He didn't really understand what 'prophecy' meant back then. All the three-year-old knew was that some people believed he would do terrible things to his father and others like him, and they wanted to kill him before he could.
Naturally, he had been terrified.
Why wouldn't he be?
He was cherished within the Vaughn Royal Family and shared a close bond with his mother's elder brother, Uncle Creusery.
Being told that his father's younger brothers wished him dead terrified him. He couldn't understand why he couldn't be close to them the way he was with Creusery.
He had asked his father about it, but Hades simply told him he would understand better when he grew up.
"I wonder how many more years I have to 'grow up,' like he said…"
He muttered with a wistful sigh, glancing at the clock as he waited for his combat training lessons to begin.
"Uncle Creusery's training is pretty harsh, though."
Turning back into his room, he remembered Creusery's suggestion, which had marked the start of his training and education.
It essentially amounted to: "Why don't we start letting him acquire skills and knowledge to protect himself in the future?"
And so, he became Creusery's student, accompanying the older prince on various interplanetary and intergalactic explorations.
He had seen many things, experienced much, and learned a great deal through this method.
Of course, that was just a side aspect. The core of his training under Creusery focused on combat, specifically swordsmanship and unarmed fighting.
Creusery had suggested that Arthur learn multiple weapons, but advised starting with just one and expanding his skills later in life.
While Creusery oversaw that portion of his training, his mother taught him about base energy manipulation and magic.
Arthur discovered that, in addition to his base magical power, he could learn to use Aura, a unique and independent energy generated directly from an individual's energy core, similar to magic power but distinct in its nature and application.
By default, Aura was non-elemental, though it could loosely resonate with a person's elemental affinity, making it easier to align aura-based techniques with that element.
Each being's aura had a 'signature' colour, often mirroring physical traits like eye or hair colour and reflecting their personal essence. While the colour was purely aesthetic, it served as a unique identifier, making aura as recognisable as a fingerprint.
Unlike magic power, aura was almost exclusive to Warrior-type combatants.
He also had two other energy sources within the core near his heart. Although everyone around him refused to explain what they were, he could already sense that one matched his father's primary energy—divinity.
'So I'm meant to be someone who can end the gods, and I possess the default power of gods.'
That was his thought upon realising this.
Since no one intended to teach him how to use it just yet, he concentrated on magic training under his mother, first discovering that he had an affinity for many of the known attributes.
His mother began by training him in the four basic attributes of Fire, Earth, Water, and Wind, before moving on to the other attributes.
During this training, he also found that his offensive spells were consistently stronger and more efficient.
In every spell circle, the circle or ring represented the flow of magic, ether, or whatever energy was being used to cast the spell.
The mark at the centre indicated the element or attribute being used, while the letters beneath the mark described the type of spell being invoked.
The more rings a spell circle had, the higher the spell's tier.
Arthur discovered that even a simple Tier 1 or 2 offensive spell, if designed to cause 'Destruction' on impact, would always manifest at least twice as much power in his hands.
What initially seemed strange to him was quickly explained as him being his 'mother's son,' since she apparently exhibited the same trait.
Arthur's life wasn't solely devoted to training.
He had hobbies, ranging from gaming to reading, through which he learned many concepts and notions about the reality he lived in.
What was a Planet? A Galaxy? A Universe?
He first learned about them from books, then witnessed them first-hand during Creusery's off-world excursions.
It was during these same journeys that Arthur came close to truly understanding the meaning of a word he had encountered in a book he once read—'Trauma.'
There had been some kind of plague and a self-replicating infestation on one planet, a story Arthur didn't fully recall.
What he did remember was that Creusery decided the best way to handle it was to destroy the entire planet… and Arthur happened to be watching when he did it.
For Creusery, it was a minor matter, but for Arthur, he had never imagined such a thing was possible.
One moment, he was observing the planet, watching spaceships drift away, and the next, it exploded in familiar black flames.
The relative ease with which Creusery accomplished this made the then six-year-old Arthur realise that this was far from the first time his uncle had done it.
Arthur had fought and killed monsters before during his training, even though he initially found the act repulsive.
But he had never killed a sentient humanoid like himself, nor had he ever seen one die.
The first time he witnessed such an event was the destruction of an entire planet of sentient humanoids. Understandably, the boy nearly went into shock.
Creusery, however, made no effort to console him.
Instead, he said something completely unexpected to Arthur at the time.
"You said you admired your father, didn't you? And that you wanted to reach his level of power one day?
This is the bare minimum. Not just him, but almost everyone around you, your mother, grandparents, and the Nobles you see around the castle daily, can all do this at least.
And just like them, the people after your life now, and those who will come in the future, can do the same."
"!"
The thought that beings capable of such terrifying acts were after him filled Arthur with fear, and seeing this, Creusery smiled wryly.
"Just understand that this is the bare minimum you should strive to reach and surpass by leaps and bounds. That way, those who pursue your life or seek to harm your family wouldn't be able to touch you.
That's what your father and mother want for you. If you can keep yourself safe no matter what anyone does, your parents will be happy. Don't you think?"
His words struck a chord within the young Arthur, and though he didn't realise it at the time, Creusery had added the mention of his parents merely to ease his hesitation.
After all, Arthur had begun to notice his parents' actions to protect him.
Or rather, they allowed him to notice. It was all part of their plan to give Arthur a glimpse of the kind of power they wished for him to attain, and Creusery's demonstration was simply the final piece of that plan.
Of course, Arthur didn't immediately accept or agree with Creusery.
It took time, and he was even a little frightened of the space explorations he had loved so much. But after months, he eventually concluded that his uncle was right.
It was sometime after this that he took the life of a sentient humanoid for the first time, one of the weaker Inferior-Stage Master Realm demigods, part of a group of assassins his parents had dealt with.
Were they merely grunts, or had they sent a weaker god to slip under his mother's radar?
Arthur didn't know. But for the sake of his peaceful future and his desire to survive, he did not hesitate to plunge his sword into their chest.
From that point on, his training with Creusery intensified, with the older prince showing young Arthur more during their expeditions.
He also taught Arthur how to conduct himself as a Prince of the Devildom, how to interact with Nobles and other influential figures across the universe, and the importance of gaining allies who could support him in the future.
At the same time, Creusery revealed the darker aspects of people, the lengths they would go to achieve their desires, the sacrifices they would make for power, and many other harsh truths that opened Arthur's eyes to reality.
In the years that followed, witnessing Creusery destroy a planet to eliminate an interstellar threat no longer fazed him.
"Arthur. Training time."
Creusery's voice echoed as the door to the outer room opened. Hearing it, Arthur set down his pen, closed the journal he had been reading, rose from his seat, and grabbed his training sword.
"Coming!"