Son vs. Father (Spoilers From This Point On)

"Why's this still up?" Isaac asked Elizabeth, "I thought you said that Merlin, Escanor, Hendrickson and one of the four Arch-angels came here to stop them?"

"I don't know but I have a bad feeling about this." Elizabeth told him as they all looked at the barrier of darkness. Isaac walked up and set his hand against it. Suddenly a hole appeared in the barrier and they walked in. As soon as they did they felt a massive amount of magical power coming from the castle. Isaac teleported all of them into the main throne room before he threw up a Perfect Cube.

"Merlin status!" Isaac yelled to her.

"Your father is making it quite difficult to pass. Even Escanor is having trouble." Merlin explained to him as they watched Zeldris form a black hole above his head.

"I'll handle it!" Isaac told them as he teleported out of the cube. He and Zeldris locked eyes as the black hole disappeared. Escanor tried to attack Zeldris and Original Demon went for Isaac.

"STAND DOWN!" Both of them yelled making both Escanor and the Demon stop.

"If you want to fight then go for each other. Me and him are going to settle this." Isaac told them as he walked up to Zeldris.

"Why are you letting Meliodas do this?" Isaac asked him when they were only a foot from each other.

"So Gelda can be unsealed. Why don't you help us?" Zeldris asked him calmly, "I know you want her back as well."

"Not at the cost of innocent lives." Isaac told him before everything went silent for them. Suddenly the sound of metal hitting metal rang out. Zeldris had swung his sword and Isaac had blocked it with his glove. They began to trade fast blows, each one being blocked by the other. The sparks of metal hitting metal began to fly out before Isaac kicked Zeldris away. Zeldris came back and slammed into Isaac sending him flipping into the air. They began to clash in the air causing the ruins of the castle shake. Isaac slapped Zeldris' sword away before grabbing his head and slamming him into the ground. Zeldris wrapped his legs around Isaac's arm and flipped him. They rolled away from each other and came to a sliding stop. They released their darkness and charged each other again. They hit each other in the face before beginning to trade blows again. Zeldris did a feint swing and spun around hitting Isaac in the face with a back hand sending him rolling away.

"Wasn't Isaac way stronger than this before?" Diane asked the Sins as they watched two move ridiculously fast.

"He used up all of his magic when he turned before. He's running on fumes as we speak." Merlin explained to them.

Isaac put a Perfect Cube around Zeldris before he could reach him. The cube caught Zeldris off guard and Isaac removed it quickly to hit Zeldris in his face. Zeldris stood still and his black hole came back. Isaac was being sucked into it before he slammed his feet into the ground making him slow down.

"Absolute Cancel!" Isaac yelled and the black hole disappeared again. He threw a hell blaze fire ball at Zeldris making him jump away. Before he could react Isaac flew through the flames and punched him in the chest hard enough for Isaac's left glove to break. Zeldris launched back and bounced off a wall. Before either of them could send another attack the castle began to shake. They turned around and seen that Meliodas had completed his transformation.

"Finally!" Zeldris yelled as he ran up to Meliodas, "Now keep your end of the bargain!"

"GET AWAY FROM HIM!" Isaac yelled but it was too late. He watched Zeldris crash through a wall and not get back up.

"Who are you really?" Isaac asked 'Meliodas'.

"I'm you Grandfather Isaac." The Demon King told him with a smug grin.