Deep behind the capital we see tones of cells that contains the dangerous monsters that The lone wolf knight of thr round table have captured for years as these cells are protected by well known and trained knights as they make sure nothing will never escape.

Going deeper into the dungeon we see a large metal door covered by chains that holds one of the most dangerous beings in their lives. We see two knights protecting the cell as they stand guard with spears at the ready as they took there and ready for theie shift to end so they can go and get some sleep or eat.

They were standing there doing their job when suddenly there was a slam coming from behind them. They slowly turn around to stare at the large door and suddenly there was another slam which moved the door and chains, making a noise as the two knights aimed their spears at the door as it keeps slamming at the door more and more.

Male Knight 1: We must warn Lord Eric and the others! Tell them that the dark demon is breaking out.

His partner nodes and runs off while at the same time more knights came over and added the other knight as they pointed their spears at the door as it continues hitting at the door more and more. Then a final hit breaks the chains and it fell hard onto thr ground as they look up and everything was slient.

They were on guard mode and have their spears at the ready for the doors to break. Moments later the door does break as the twin doors swing open follow by a strong wind that made them move back a bit.

Suddenly a invisible force pulled the knight towards the darkness and he was gone within a second. The rest ready theie spears and we see more knights at the second floor with crossbows as they aim at the darkness as they hear screams follow by slince.

Suddenly a helmet was throne and hit the ground as we see it belong to the knight that was pulled with blood on it. Then they hear footsteps and seconds later a evil knight came out of the darkness while trails of smoke behind him as he step out of his cell and look around him.

The being glare at the knights and then the knights with spears all charge towards him with a battle cry. The dark knight just simply swipe his hand to the left and immediately the knights was blown away to the right and slammed hard onto the wall.

The Knights on the second floor fired their bows at him but he rasies both his hands, stopping the incoming arrows mid air and then crushes his hand, breaking them in half and dropping them onto the ground.

Seconds later the dark Knight snap his fingers and the Knights on the second floors heads snapped and they fell onto the ground. The dark Knight growled as he look up and then he turned into smoke and goes straight up.

(Meanwhile)

We see Eric and the rest of his house hold minding their own business as Eric is cleaning his sword when suddenly the throne room doors burst open and a knight rush in and called out.

Male knight: My lord! The dark demon has broken free!

Eric: (shocked) WHAT?!

Alex: (shocked) That's impossible! How can he be free?

Jeanne: We must hurry! Gather all the knights and be ready whne he comes out!

Male Knight 2: Yes my Que-

Then his neck snapped which shocked everyone as he fell onto the floor and behind him was the Dark demon as he lower his hand and look around the room and then turn to stare at Eric and then spoke.

???: I see your ancestors taught you well but not well enough.

Then Alex, Igris Robert, Alice, Eydis, Mordred and Teresa charge towards him but he push then all back as they slammed onto the wall and hold there off the feet while he slowly walk towards Eric as Artoria and Jeanne try to defend Eric but he swing his wave to the left, costing them to be sent flying and land hard onto the floor as Eric pulled out his sword and launch towards him.

However he grab his sword when Eric goes to swing at him and moments later his sword turned into rust ad he grabbed Eric by the neck.

???: Your ancestors was strong in the past when they defeated me but now I am stronger all because my filled up rage and my darkness rising within me.

Eric: Whatever it is you may want I will never kneel to you!

???: I only want one thing. Your ancestors told me that he is dead but I can feel him, I can feel his darkness and he is alive.

Eric: What are you talking about?

He squeeze his neck even more, making him lose some air as he glare at Eric's eyes and then said.

???: I want my brother. Bring him to me.....at once.

He then pulled Artoria towards him and grab her by the neck with his other hand as he drops Eric as he fell onto the ground as he look down at him and tell him.

???: Bring him here and now or I will kill one of your wife's. Still refuse then I will kill everyone in this room and leaving you to suffer to seeing your whole family die right in front of you!

Eric looks at Artoria and everyone else who is struggling and look up at the dark demon as he knows he can't risk us whole family being killed. He hesitated at first but with no choice he slammed his fist in frustration while the dark demon let's out a evil chuckle.

(Moments later)

A portal opens as Y/n, Rias, Issei, Asia, Koneko, Akeno and Kiba exit out of the portal and arrived at the front entrance to Eric's House hold as the gates open and they walk through.

Kiba: Wonder why Eric wants us here as soon as possible?

Issei: I don't know man but if it's about Roberto training please kill me.

Y/n was looking a bit worry for some reason so Asia ask him.

Asia: Is everything okay Y/n?

Y/n: I don't know but Eric is not a type of guy who is impatient unless there is something serious. I just hope it not bad news.

Koneko: Say is it me or is there no guards letting us in?

Akeno: Yeah now you think about it I don't see no one around.

Rias: Yeah something doesn't feel right.

They arrived at the front door and without anyone letting them in they open the door and everything was dark. They make their way through the hallway, seeing no one while they were walking through and soon arrived at the throne room.

Y/n reach over to grab the door handle when suddenly he had a sudden feeling which cost him to take a few steps back.

Rias: What's wrong?

Y/n: There is something behind those door. I can feel its power and its strong but.....familiar.

He look back at the door and then open it as the door pushes open and they were shocked to see Eric's and his house hold family being strapped onto the wall looking injured then ever while they see a dark Knight sitting on the throne with Eric on his knees as he look up at them and then said.

Eric: Forgive me Y/n.

Issei: (shocked) Who the fuck is that guy?!

Then the dark Knight swing his hand backwards costing Issei to fly over towards him and he grabs him by the neck while he gets up.

Rias: Issei!

Y/n: Let him go!

???: Ah so you hold the Red Dragon Emperor sacred gear. Very interesting but your not a true Emperor. Your nothing but a fool.

He then tosses Issei back to everyone else as Rias and the others get ready theirs magic only for him to push them back in a invisible force apart of Y/n as they slammed onto the wall.

Y/n: Guys!

He turn back only for the dark knight to be up close to him. He stared at him for a moment and circle around him a few times while he said.

???: Your not my brother but yet you hold hid sacred gear and.....his blood. Your related to us.....in fact, you are us.

Y/n: It depends on what you mean by that?

Kenzo: Those call me the Dark demon but my true name was Kenzo. I fought by my brother millions of years ago, during the devil and angel wars.

Y/n: (shocked) What?! That's impossible!

Kenzo: It's true. Me and my brother fought against the angels and those who stand against our way until I was captured by these knights and lock me up for years. Now, I am free. You may not be my brother but you hold his power and together we will rain apon an age of darkness to this world!

Y/n: Yeah about that. I'm not a villain like you, I'm fact my ancestor turn good when he sees the chaos and destruction that he has cost.

Kenzo: What?! Your lying.

Y/n: It's true. And I'm gonna redeem my ancestors actions by helping those that are needed and protecting my new friends.

Kenzo: NO! You have no one but the darkness inside of you! These.....beings are weak and they are going to hold you back! You dare to throw away everything that we have! We are gods! We should be the one that is suppose to take over this world! Not protect it!

Y/n: Well sorry but I'm not a guy who's gonna take over the world and turning evil.

Kenzo: So what does that make you? A hero? A dark warrior a hero of the light? Pathetic. You are nothing but born from pure darkness.

Issei: Well at least he knows how to kick people's asses like you?

Immediately Kenzo disappeared and reappear in front of Issei and grabbing him by the neck as he throws back his fist while he barks at him.

Kenzo: Be slient boy!

Then his fist was grabbed and immediately gets punched by Y/n in his armor as Kenzo gets up ans seeing him wearing his brothers armor but now Y/n is using it to protect his friends.

Y/n: Leave my friends alone.

Kenzo: Look at you trying to be a hero buy yet you shown to be pure of darkness. Your nothing like me!

Y/n: Fuck up man. The darkness is not in control of me. I am.

Kenzo: You are nothing but a disgrace!

Then Kenzo charge towards him and the two fought as they strike blows at each other. Kenzo blocks Y/n's strikes and punches as Kenzo grabs him bynthe head and then slammed him onto the wall but Y/n kick him back and was about to strike a blow but an invisible force sent him flying, breaking through the wall and sent him flying outside as Kenzo enters through the hole while Rias and the others rushes over to Eric and the rest.

Eric: This was all my fault. Now Y/n is gonna die because of me.

Rias: It's okay Edic. You didn't have a choice.

Issei: (smirk) Yeah and besides Y/n will beat him with no problem.

Artoria: You don't understand! Kenzo is one of the ancient knights and one of tne most powerful beings that is ever kept. His power is outclass to even Y/n's.

Asia: But how?

Eric: He must be building up his darkness and power while he was in prison. Making himself stronger and more powerful then ever before. I don't think Y/n can even beat him on his own.

Rias and the others were worried now for Y/n as they can hear explosions coming from the kingdom as they knew they have to go there and help Y/n out before Kenzo will end his life.

To be continued.......................................