Reincarnated With The Strongest System

William smashed into one of the houses inside the capital city after getting hit by a punch from Felix.

After their brief exchange of words, the Heir of Darkness immediately charged at the Half-Elf and engaged him in close combat. In the beginning, the black-haired teenager was able to evenly exchange blows with him, but after ten minutes, the green-haired Demon's movements suddenly increased, and his attacks became more precise.

"It took a while, but I have now adapted to this body," Felix said as he looked down on William who had just propped himself up from the ground. "Sorry, but it has been thousands of years since I fought. I'm getting a little rusty. Well then, shall we start for real?"

William wiped the blood that flowed from the corner of his lips with the back of his hand before looking at the sneering Demon, whose personality, and strength was vastly different from the Demon that he had been fighting since he launched a counterattack against the Demon Army.

The Half-Elf stomped his right foot on the ground before flying towards Felix who looked as if he was just taking a stroll in the park. 

Immediately, powerful shockwaves reverberated in the sky as William exchanged blows with his opponent. He had been fighting using all of the powers of his Familia Members, and yet, he was unable to land a hit on his opponent, whose smile never left his lips.

"You might be faster than me," Felix said as William unleashed a flurry of blows against him. "And I can tell that you are slowing me down, but that isn't enough to win against me."

The green-haired Demon blocked, and deflected all of William's attacks with ease, as if he was fighting a toddler.

"You were only able to overwhelm this brat earlier because he is inexperienced in fighting and didn't know how to use his strength," Felix commented. "How can a Pseudo-God lose to a Demigod? Does that make any sense to you?"

As if proving his point, after deflecting one of Wiliam's punches, the green-haired Demon unleashed a powerful kick, hitting the Half-Elf's chest, sending him crashing through several houses until he came to a complete stop.

"Hellfire Blast." Felix sneered.

A giant purple fireball, which was far bigger than the one that Felix had used earlier, descended upon the place where William lay. 

A moment later, a powerful explosion shook the capital city as hellish fires and deadly fumes rose up towards the sky. 

"As expected, you're one tough nut to crack," Felix commented when he saw William standing up from the hellish crater that he had created. "But, eventually, I will be able to crack you open and see what makes you tick."

The robe that William was wearing had been burned to tatters, but his body was relatively fine. After using the power of the Heroic Avatar, his constitution became as sturdy, and tough as Sun Wukong's, preventing the hellish explosion from dealing serious injuries to his body.

The minor injuries he received had already been healed by Princess Aila's powers which were currently circulating inside his body.

"I now understand how strong you are," William stated. "However, I still don't know who you are. I should at least know the name of the person that I am going to pound to oblivion, right?"

"Pound to oblivion?" Felix asked in a sarcastic tone. "Me?"

The green-haired Demon laughed out loud after hearing William's words. Clearly, he didn't believe that William had the ability to defeat him, which tickled his evil heart. After having his fill of laughter, his eyes focused on the black-haired teenager, and crossed his arms over his chest.

"Very well, I will tell you the name of the one that will make your life a living hell," Felix replied as he crossed his arms over his chest. "I have many names, but you can call me Aka Manah. One of Ahriman's Council of Demons, and your worst nightmare."

"Aka Manah…," William muttered before thumping the golden cudgel in his hand against the ground, extinguishing the hellish flames that were starting to spread inside the capital city, killing the residents that had refused to abandon their homes.

"Right. Have you now changed your mind? Do you wish to become Ahriman's subordinate?" Aka Manah asked in a teasing tone. "This world is ripe for the taking. The only thing you need to do is bow your head, and I'll convince Ahriman to spare you, and your subordinates' lives. So, what do you think? Not a bad offer, right?"

William's body rose towards the sky until he was standing face to face with an existence that had completely taken over Felix's mortal body.

"I'm not interested in your offer," William replied. "The only thing I am interested in is having yours and Felix's heads served on a silver platter."

Aka Manah shrugged before shaking his head in disappointment.

"I have already asked you twice, and you still refuse my generous offer," Aka Manah sighed. "I guess you still haven't suffered enough. Maybe you will change your mind after you see… your true self!"

The next moment, Aka Manah's clawed hand pierced through William's chest, grasping the Obsidian gem in his hands.

"Now, let me take a look at what you really are…," Aka Manah whispered in William's ears. "I want to see the darkness that resides in your tainted heart."

Those were the last words that William heard before he dropped Ruyi Jingu Bang on the ground. 

The golden cudgel that belonged to one of the strongest Heroic Spirits in the world lost its radiance at the same time its owner lost the luster in his eyes.

Screams of shock, and anger reverberated in the sky, as Astrape, Bronte, Titania, The Nymphs, Chloee, Charmaine, as well as the other people who cared about William, saw this unexpected turn of events.

Each of them flew towards the hateful green-haired Demon whose claws had pierced through William's chest, with the intention of ripping him to shreds, and saving the black-haired teenager in his hands.

However, before they could get near him, a dome of darkness burst forth from William's body, blocking everyone's attempts to help him.

A moment later, Aka Manah's insidious laughter spread throughout the surroundings as William's corrupted heart opened, allowing him to bring out the true darkness that lay within.