When Issei open his eyes all he can see is darkness, but there's a single throne adorned with human skulls and the color of the throne is pitch black.

And he can see a girl sat upon that throne, who's looking straight at him and she has a wicked smile on her beautiful face.

She has a has a doll-like face considered to be "too beautiful and too well-crafted", yellow pupils just like Jalter, the same pale white skin, and a long pale white hair. She wears what appears to be a black priestess garb with red outlines along with a pitch black crown adorned atop her head. ( https://fategrandorder.fandom.com/wiki/The_Black_Grail_(Servant) can't tell what the rest of her outfits are so here's her link)

??? - Ehehehehe... Ahahahahaha!

She started laughing like a maniac.

Issei just calmly look at her, he knows the woman in front of him is the itself. Just from the dark aura she emit alone which is the same when he hold the before.

After a while she finally stopped laughing.

Issei - Are you done?

BG - Hehehe... Indeed I'm done... I can feel that you have the same "Darkness" inside you that match my own. So If I absorb you with me then I shall become complete! Now become one with me, Dragon!

She talk with the same wicked smile on her face.

Issei - I refuse.

BG - Hehe, that's not for you to decide!

Then out of nowhere there's a black tentacle emerging from all around her, then they headed straight away to Issei.

They constrict all around his body. From his neck, to his arms, his legs, even his body.

BG - Ahahahahaha! Now come here!

But Issei doesn't move a single inch, you could tell the black tentacles are struggling to pull him. But to no avail.

BG - How!?

She's confused why even though she use all her power to pull him towards her, he doesn't even budge. And he's still has the same calm look from before like the tentacles that wrap around him are non-existent.

Then Issei emit his own aura and the tentacles are shredded to mince just from his aura alone.

BG - Wha-!?

She become amazed by the sheer power she felt just from his aura alone. But she become more ecstatic because if she can absorb him then, she will truly be complete and even stronger than ever!

Then she summoned thousands of humanoid looking dark substance to attack him.

BG - Hahahaha! Great, great! Now let's see how you can handle this!

Then the army she summoned launched their attack at him.

-After a while-

The girl face lose her smile and she has a scowl on her face.

BG - WHY! WHY WON'T YOU GO DOWN!!?

She's mad that the man before her won't go down like she wishes to.

Issei still at the same spot when he arrived here, but the army she summoned are all over the place. They are scattered around him.

All he do is launch normal attack whenever that thing come close to him and they are destroyed like a clay figurine whenever they received his attack. At one point she started summoning a shadow like being that has the form of Jeanne and other strong looking humanoid.

But they are all destroyed just from his normal punch or kick.

And then they tried ranged attack but also to no avail, he slapped away every projectiles that come his way but even if some hit their target, forget about injuring him they can't even put a scratch on his outfit.

Issei still has the calm look after all the 'battle' he had and he doesn't even broke a single sweat after all that.

Issei - Are you done?

He asked once more but this time his red eyes shining a little bit.

BG flinched when she met the stare from his eyes, this is the first time she feels intimidated ever since she came into existence. She just see everything she see as a toy and she loves to mess around with their so called 'Wish' Her wish are to destroy the world but sadly her power is not capable enough to do that.

But when she sensed the power from the rift she became ecstatic, if she could absorb that power then her wish will finally be fulfilled.

And when she saw it first hand, she become more assured that this man in front of her is the key to her wish.

Alas she underestimated the man and she can't took him down no matter what she did.

Just when she get even desperate she remembered she still hasn't tried that thing.

BG - Heh, I admit you're strong but this will be the end.

Then she summon a black mist and surround Issei within it.

BG - No matter how strong you are outside, deep inside you must have a certain negative emotion and that shall be your downfall.

Then she got up from the throne and head towards him...

-

When Issei got surrounded by that black mist, he feels his surrounding change. He's back to the time where he find out the girls is cheating on him.

He saw when Rias & Akeno kissing that man, he saw when the rest of the girls are acting intimate with their new boyfriends. And here he is watching it all over again, after that he saw them throwing insults and hitting him down over and over again while their new perspective boyfriends just laughing in the background.

They are not the same girls he once come to love, the look in their eyes, the pure contempt they had on their face when looking at him.

Issei doesn't realize he has tears streaming down his face at this moment, he just calmly looking his memories replaying back. The happy memories and sad memories, and then he come to the point where he almost died just from the sheer despair he felt during that moment.

How he just want to die, just so he won't feel the pain from getting betrayed by those he loved. If not for Ddraig then he must have died long time ago.

And after what it feels like an eternity he finally saw his new memories he have with the new woman he found.

The time he spent with Semiramis, his Shishou, Jeanne, and Jalter.

Deep inside he still doesn't trust anyone, he still thought of them all the same as Rias and the rest. And what's more he feels afraid if the same stuff happen once again, but then...

He saw from all of his new memories, that he has been wrong for thinking every woman he met the same as his old Lover.

The care they gave him, the joy they share, the warmth, the trust they gave him by telling all about themselves. How Semiramis got betrayed, how she felt about him. And his shishou who even though strict with him but still never lose the loving care she gave him. How she tell her secret why she's looking for a perfect candidate to be her student.

And even the 2 new woman who swore their soul to him without hesitation. They are really silly but that's their beliefs, their beliefs for him.

He knows they truly love him deep inside but he's too afraid to move forward, to accept their feelings. In fear of the betrayal happening once more.

But now he realized how wrong he was. Then he finally found the courage he needs to move forward towards the better future.

And unknown to him his souls which constantly contradicting each other have started to become one, they are balanced just like yin and yang. He has another breakthrough, he break the shackles which binds him to go to the next step. What it meant to truly become The True Dragon of Domination.

He shall dominate everything, Dominance. Control. These things the unjust seek most of all. And so it is the duty of the just to defy dominance and to challenge control.

He shall have dominance and control over everything, even his feelings.

To know sorrow is not terrifying. What is terrifying is to know you can't go back to happiness you could have. Fear is not evil. It tells you what weakness is. And once you know your weakness, you can become stronger.

-Outside Issei's mind-

BG came close to Issei's body, he has his eyes closed like he's fast asleep.

BG - Hehe, At last... Finally My wish shall come true! Now you shall become part of me.

When she extend her hands towards Issei.

He suddenly opened his eyes and grab her hands.

BG - !!!

She become shocked

Issei - Thank you for making me realize something.

Then he threw her away. She crashed against the throne and cough a bit of blood because of the impact. Then she saw Issei floating with his Dragon wings spread behind him.

He closed his eyes and put one of his hands over his chest then started chanting

Issei - "I, Who shall awaken.

Am The Red Dragon Emperor who control the principle of domination

With infinite hope and dreams, I shall become the protectors of my loved ones.

I am their light in the darkness.

I shall promise you! A future that shines brighter than any light.

Ally to good! Nightmare to evil!

I shall become the True Red Dragon King of Domination!"

"!"

Then the whole darkness around him are blown away.

(Issei's new form are that of a dragon that look like Deathwing from World of Warcraft but with red scales)

Then a majestic red dragon stand before her, his mere presence bring shiver to her core. She feels tiny and insignificant before him, she have the urge to just submit to him.

Issei gave a loud roar after his transformation and every wyvern and the black dragon outside the are shivering and bow down towards his direction, like they are welcoming The True Dragon King awakening.

Jeanne and Jalter who are still panicking when their new master disappear noticed the anomaly and they saw the are shivering fiercely like its threatening to break any moment.

They also heard the roar which contains so much power.

After a moment Issei stopped his roar and set his gaze upon BG once more, she felt her heart stopped beating when those gaze lands upon her. Then she heard his calm voice inside her mind.

Issei - Summon back all the wyverns and dragon you summoned.

BG can only comply because she knows there's nothing she can do to this Dragon before her.

Outside all the wyverns and dragon disappear into a particle of light while they are still in their previous position. And the humans give a loud cheer when they saw the wyverns disappear.

BG - ...What now... Will you kill me... Heh! A fitting end for a being such as myself and I consider it as my honor to be killed by you, True Dragon King!

Issei didn't answer her question right away, he just kept staring at her.

Just when BG started feeling irritated she heard him once more

Issei - I won't kill you, I don't see the point to kill you at this point. Even if I do kill you now, you will just be reborn again in the future. Because you're made from all the humans negative emotion, as long there's human exist then you will keep coming back. Isn't that right ? Besides you are a necessary existence anyway.

BG is at loss for words when he said all that, its true that she will keep coming back as long humans existed but its a first that someone said that she's needed.

BG - ...What do you mean I'm a necessary existence? Don't you know what I've done so far!? How many lives have I take!

She couldn't help scream out loud at him.

Issei - You are a reminder to the humans. To remind them to stand together in peril, you are what the humans needed. A Saintess might be good for them but in the end it still won't stop the inevitable... War. War is omni-presence ever since the olden times. Then, rather than having humans kill each other then its better to let them fight a common enemy. And that's where you comes in, a necessary evil you might say.

And its not your fault for being born, it is their sin. Not yours. In the end they reap what they sow, in some way you are the product they created.

BG once more become lost at words because of what he said.

Issei then transformed back to his human form.

BG - Heh... What was that... You will regret not killing me now...

She looks down while saying that.

Issei - Perhaps... But that's just what life is nothing is true everything is permitted. The world isn't perfect. But it's there for us, doing the best it can....that's what makes it so damn beautiful.

He says that with a smile on his face, and BG who saw that become a little absent minded but she just scoffed at his words not denying it.

BG - Hmph... Go away... idiot...

Then she created a rift below his feet and he's gone.

BG - ...thank you...

She mutters at the end.