Evolution.

The annoying itches slowly and steadily turned into pain. Erik's vision started to go blurry and he felt his bodily functions ceasing. Putting one hand on his head, Erik almost stumbled down on one knee before he barely caught his balance.

The trio had just left the palace when Muzan noticed something was wrong with Erik.

"Mr. Erik, are you-"

WHOOSH!

Erik suddenly grabbed the two of them by the waist and jumped up into the air with as much strength as he could muster.

"What the...."

Muzan couldn't even open his eyes to look at Erik because they were speeding through the air at such an insane speed. With one leap, Erik flew over the entire city and landed quite a ways off in the desert. If one took a look back at the city, they would see that the city was nothing more than a tiny dot in the distance.

BOOM!

Erik stomped his foot on the ground and caused it to cave in, making a large entrance there. Although sand started to quickly fall in said hole, Erik dropped the duo on the ground and started to leave.

"You two need to make do with that makeshift shelter for now. Something is happening to me and...ugh...I need to go take care of it."

Erik didn't wait for a response. He ran off in a random direction with blinding speed and tried to jump through the air once again.

THUD!

His legs gave out and he fell to the ground, tumbling through the sand at the same speed he was moving with. The pain that was steadily getting worse before suddenly became excruciating as Erik saw the Shinsu around him funneling into the six black pearls on his body.

"Aghhhh! Shit! This hurts too much!'

They were like a vacuum sucking the Shinsu up until blue cracks started appearing on Erik's body. The Shinsu going into was simply too much for his body to handle. Every bit of Shinsu for miles went into his body.

Erik started to shout as the pain got even worse, causing the atmosphere to warp and the sky to turn dark. If he kept this up, the destruction that would ensue would be unprecedented.

BOOM! BOOM!

Shinsu in the form of lightning struck the desert floor, enraged at the unnatural entity being born into the world.

But even that couldn't escape the ruthless suction power of the black pearls. It seemed like they would never cease their absorption. Unfortunately for Erik, the more Shinsu his body took in, the more suffering he had to go through.

The cracks continued to spread all over his body until...

BOOM!

It exploded into a massive dome of concentrated Shinsu, illuminating the land for kilometers. The sheer power contained in the dome could probably destroy 10% of the floor of it wasn't controlled. Suddenly, a large black pearl appeared inside the Shinsu dome and started compressing it into a humanoid shape.

BOOM! BOOM! BOOM!

The pearl was beating in the center of the dome like a heart would. Every beat of it was powerful and reverberated through the desert like a massive drum. As time went on, the humanoid figure got more and more defined, forming limbs lined with large rippling muscles.

As the Shinsu was fully condensed into a humanoid figure, it slowly started revealing a blue skinned being lined with cracks all over it's body. The cracks were like pathways or veins that spread all over his body, connected to the large black pearl in his chest.

Silence.

The atmosphere finally calmed down as the black pearl stopped absorbing Shinsu. But even then, the Shinsu was so thin that any other person in the vicinity would be actively gasping for breath.

The other five pearls reformed and went back to the specific points on Erik's body where they were located before.

The pain subsided immediately and Erik fell down to the ground and started feeling around his new body. As soon as he made contact with it, Erik could tell that it wasn't human. Well, it wasn't like he had a problem with that. Erik was accustomed to being less than human. [A/N: Just imagine Boros with a blank mask thats actually part of his face. No, this is not a permanent thing. He'll be back to looking like Sukuna/Yuji in time, and it'll be a more adult version.]

What he did have a problem with immediately though, was the fact that his eyes were covered by something. Rubbing his hands over it, he felt a hard covering over where his face was supposed to be. Maybe it was his new face? Erik couldn't even begin to imagine what was going on with his body.

Erik tried to rip it off but he found no sort of grip or anything around it. It just felt...blank.

'Although I cant see physically, what are these colors I'm noticing around me? Is this scarce blue energy supposed to be Shinsu? Hm? What is this purple energy flowing around me?'

Erik was trying to figure out the changes that had occurred to his body but he didn't even know where to start. Everything just happened so fast.

He was just about to contact his A.I when another problem reared its head.

'Wait, I can't talk?! What about sense of smell? I can't do that either? I could only hear and touch. But wait, if I can't smell, that means I can't breathe. Does that mean I've evolved enough now so I can survive without breathing in Shinsu?'

Erik immediately sat down on the ground, although he even stumbled to do so because of his lack of control over his new body, and started thinking about his situation. He couldn't see, talk, smell, but he could hear and touch.

Strangely enough though, Erik had a feeling that this was an advantage. There was something about his new body that he was missing because there was no way he would evolve into something weaker.

It was then that Erik came up with an idea that even he had come to regret in hindsight.

'Since the rest of my senses were locked, or at least changed, I wonder if my hearing was enhanced? Lets see, if I do this...AGHHHHHH!'

Erik scrambled to cover his ears as he heard hundreds or probably thousands of thoughts and voices flowing into his head. From young to old, human to animal, mortal to spirit, Erik's senses were being completely overloaded by every one of them.

'Stop, stop, STOP!'

He barely managed to stop the influx of voices before it became too much for his mind. He had never imagined that something so incredible but painful would've happened just by trying to check his hearing.

'What...was that?'