The experiments on the demon that Arthur had found in the cave, had given him satisfying results.

That is, becoming a demon was indeed possible for Arthur.

He was worried that his body, enhanced by the perfected super soldier serum, might cause some complexities or even entirely resist the change but his worries were unfounded after all.

In addition to that, in the limited time he could spare for the experimentation on the demon, he found that his cells...

.

.

.

Arthur opened his eyes with a start but unlike his usual dark blue eyes, behind his eyelids were crystalline vibrant blue eyes with a black  "?" engraved in the center of both of his pupils.

Of course, Arthur didn't know that his eyes have changed, or his whole appearance for that matter of fact.

But the first thing that greeted his eyes was something that surprised him a little, it was a wooden ceiling with traditional Japanese lamps illuminating the surrounding in a golden hue.

'No...', Arthur groggily squinted his eyes.

'It isn't just any wooden damn ceiling. It's one of the ceilings in the infinity castle! Infinity fucking castle!'

He rose his torso up and sighed. He noticed that his forearm had changed a bit, it was quite muscular now. The other most remarkable change would be its complexion which was quite paler than the original and his nails too. They had turned black.

Then he took in his surrounding, the interior of the Infinity Castle. The castle's interior was a twisted and grotesque mockery of traditional Japanese architecture, with gnarled and twisted columns, labyrinthine corridors, opulent decor, and a multitude of spires that seem to stretch up into the... infinity.

"Where am I?" Arthur muttered for the sake of 'custom' and for whoever brought him here to know that he was awake.

The next instant, a new sort of structure appeared in front of him. It seemed like a stage. A traditional Japanese indoor wooden stage on which a woman with a Biwa in her delicate hands was sitting.

She struck one of the strings in her Biwa and just as she did Arthur felt a new presence arrive.

The mere presence made each strand of Arthur's body stand erect and send a bone-chilling shiver down his spine.

Arthur turned around to see a pair of red eyes looking at him condescendingly.

It was Muzan.

Arthur bent down and bowed to him without any word.

"Why do you bow?" Muzan asked.

"Each fiber of my being said so, that's why," Arthur replied without a moment of hesitation.

Arthur couldn't see Muzan's face right now but he imagined him smiling after receiving a satisfactory response.

"What do they call you?" Muzan asked for Arthur's name.

But Arthur wasn't planning to give him his real name, simply because his name was of foreign origin. It would seem odd for him to have such a name, and raise some questions which would be a bother to answer. Though Arthur had inherited his features from both his British father and Japanese mother, he looked more Asian than British. His mother's genes were more dominant, apparently.

So his features won't be troubling but his name would. He'll always have to explain his name to anyone he'd meet in the future.

So he chose to lie.

Muzan had the ability to read other demons' surface thoughts, Arthur knew. But Arthur had also gained something that will prevent Muzan from doing so or at least doing so accurately... Mental and Astral sheild. And this ability was more than just a simple shield, Arthur had found. Muzan could only see what Arthur showed him.

"Heito." Arthur gave Muzan his mother's surname.

'When I was small, I thought it was 'Hate' instead of 'Heito'... well...'

Arthur's head was still touching the wooden floor.

"Heito... You are now immortal, ageless. No injury will cripple you nor will any illness ever limit you. You have transcended humanity to become something more... You are now a Demon." Muzan explained, his voice was clear and absolute, sending the meaning directly into Arthur's brain.

"Your sole purpose from now will be to serve me and my cause."

And then...

The rules were explained.

No, they were laws...

He was told the way of life of a demon.

He was also given a mission...

And then...

After everything that needed to be explained was explained, he found himself in a dark cave.

Arthur got up and sighed.

'Being in the presence of Muzan was becoming quite taxing, both mentally and physically...'

While being in the demon lord's presence Arthur had to constantly have total control of his thoughts and mouth, his action and reactions, everything. Though this time it was only for introduction purposes that Muzan was in front of him, the next time it'd be either for a mission or his introduction to other upper moons, Arthur guessed.

There was practically no light in this cave and yet he could see perfectly, even the color of his  Kimono, tattered from the fight last night, looked as vibrant as if it was day even the crimson dried blood on it.

He took out a full-body mirror from his inventory and examined his physical state. His hair was fortunately still black, like his mother's. But his eyes were now crystalline blue and seemed to glow a bit.

'Seems like I'm Gojo Satoro with black hair.' Arthur shrugged.

There wasn't much change in his physique other than gaining a pale complexion and more muscle.

He smiled as he looked at himself again...

"Hmm, just as 'he' said, I have two question marks instead of numbers engraved in both of my eyes."

"Upper Moon : Unknown."

'Muzan had said that I should be stronger than all of the lower moons, he said to consume the blood of humans and grow powerful, and also get my rank. And to get my rank, first I will have to challenge the one in the lowest rank, upper moon 6, defeat them, and then I'll become upper moon 6. Even that task might take a decade or even centuries, he said.'

"Daki, huh..."

'So much work to do but...'

"I guess, I'll check my abilities for now. I wonder what my Blood Demon Art does."

The aspect of experimenting with his new powers always made him excited, just like that time in HOTD world when he found out about an additional property in his inventory. That it could be used as a high-pressure water cutter.

Anyway, he knew that he has infinite stamina now. But he still needed to check other things like how much weight he could lift, how much his grip strength improved, his reaction time, the speed of his regeneration, the amount of bearable pain, and also...

Suddenly a realization dawned on him.

He smiled, "Yeah... if do it right then I can completely remove my limit on the number of undeads I can control..."

Demons can also alter their bodies however they like. They can even control their hair as a matter of fact. They can grow extra limbs if they wanted. In fact, Muzan has seven hearts and five brains located at different places in his body.

'If I can create another brain that has the sole purpose of controlling the undeads on my will, then..."

.

.

.

.

.

.

.

.

.

Muzan, after who knows how many centuries later, was feeling a bit hopeful. He had finally created a demon that at least had the potential to conquer the sun... Heito.

When Muzan was injecting this one with his blood, the human boy soaked his blood like a sponge and even acclimated it in record time.

His body seemed quite accepting of the change, it was as if he wasn't human in the first place. No other human had displayed such accepting nature to Muzan's blood. Even Kokushibo didn't have this much affinity to Muzan's blood.

But since Muzan didn't want to kill this one just yet, he stopped injecting him with more of his blood after a certain point even though there were no signs of rejection.

He wanted this one to adapt to his new form and become more powerful by absorbing more human blood. And when he's ready, he'll inject him with more of his blood... and then finally...

It won't take much time, a couple of years, decades even... but Muzan was a demon of patience...

===========

Thanks for reading!

Also well, really sorry for this announced break. I never planned it to be so long, you see I had college fest so got pretty busy. And now the bastards gonna take midsems..

fuck clg!!

Also, I've posted a short story go check it out : The Undelivered Letter 

Anyway, like and comment your views! They are really motivating (help my dopamine addiction)!

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