Infernal comedy: A Rias Gremory self-insert (Highschool dxd/Sandman Au)

Draconic wings erupted from the back of the Gremory pawn in a shower of gore. “My power,” the voice of the dragon residing in his sacred gear rumbled “is more than only increasing mere power. Your king was right to say that you were no human. You are a devil with a dragon soul boy. Don't think about what should be. Think about how got want it to be!

Thinking about what he wanted and not about things that were supposed to be the dragon had said.

Deadly Snow icicles looking as sharp as razors fell from the sky like a hurricane targeting the brown-haired boy.

With a bat of his wings, his fire propagated like a fog in the air to counter the black ice. Ice and fire met and Ice was found in the winner.

The ice continued its advance toward him. The pawn crossed his arms in an X and used his wings to act as another layer of defence.

The snow knocked the boy out of the sky pummeling him through the ground. With a snarl of rage and hatred, his flames were reignited stronger and brighter than before.

With a fist, he broke through the hurricane, tearing into the sky a giant hole. The pawn didn't stay idle in his moment of respite. He exploded out of the ground making the Earth quake as if an angry god had woken up.

There was no point in staying in one place. If Issei wanted to win, he needed to get rid of the god in the quickest way possible.

Icy mist escaped his breath as the temperature continued to lower. The cold air on his body felt like thousands of nails prickling and trying to pierce through his skin.

It was as if every step, every action he was taking was one the world itself was punishing him for. ‘You are fighting against a god. It's not as if the world was against you because you are actually fighting the world partner,’ the Dragon's voice said in his mind “But fortunately, you are no child of man anymore. In you flow the taint of the Morningstar and the witch, in your soul flow my essence. Don't stop! Don't hesitate and I promise you before the endless that you'll win!

His sight met the gaze of the Japanese warrior god. With a flick of his will, four orbs made of demonic and draconic energy arose from nothingness. 

Each of Those orbs contained enough power to lay waste to Kuoh in its entirety. Each of them was capable of creating as much if not more destruction than a nuclear bomb.

They flew toward the god. With one movement of his arm, Bishmamonten batted one of them with his spear making it fly toward the Horizon where it landed and plunged the world Into insanity and crimson. 

Issei sent a right hook to the face of the god. His fire-covered punch met the face of the god and found itself useless. 

The pawn didn't stop. He grabbed one of the orb orbiting around him as if it were a star and threw it in the face of the deity. He didn't wait to see if his attack had landed.

The pawn pivoted using his wings and with a reverse roundhouse kick, he sent the two remaining orbs to the face of the god.

They clashed against something intangible protecting the god, separating him from the world. Issei finished his rotation with another kick trying to push his orbs through the barrier separating him from reaching the god.

Frost erupted from the god like a frozen ocean extinguishing the orbs of Issei. Issei’s eyes widened in pain as the frost licked at his skin. 

His wing instinctively batted away trying to distance him from the threat he knew would kill him if he didn't move.

He moved, pushing his wings to escape a cold merciless death but unlike the previous times, the attack and the god followed after him.

Bishamomten with one move disappeared from his previous place to reappear behind the brown-haired teenage boy.

His spear moved with the goal of piercing through the brain of the red dragon emperor. Issei’s instincts saved him. He leaned on the side sacrificing one of his wings to survive.

The spear of the god cut through the draconic wing as if it were butter. The wings that had been cut froze before coming to decay.

“Partner, your wing!” the voice of Ddraig warned Issei. Issei could feel something wrong at the level where his wings had been punctured. 

With one thought, his own fire turned against him burning through the remains of his wing and cauterizing the flesh.

The pawn began to fall from the sky losing control of his flight due to the loss of one of his wings.

His eyes found a plot of Earth in the middle of the ocean that stayed proudly above the ocean.

He angled himself so that he would end his flight on it. He fell on it and glided, the force of his fall not allowing himself to stop instantaneously.

One of his hands dug into the ground to help him stop. He turned toward where he knew the god was. The unnatural eyes of the god were fixed on him.

“Partner, you noticed didn't you?” Ddraig asked Issei.

“Yeah, I did,” he answered. The ice of the god wasn’t only cold to the point that just being best from it felt as if his body was shutting down. It also reminded Issei of the light of the fallen angels he had fought against.

He could feel it in his blood poisoning him from the inside, weakening him at every instant, working to destroy and rot his The difference was that the ice of the god felt so much worse than the light of the fallen he had fought.

The god had given Issei his name. Bishamonten was a god most Japanese people even if they were not religious knew. He protected the nation against foreign invaders and fought and destroyed evil.

Issei guessed that this description of the god was much more literal than a lot thought it was.

As long as he would be fighting against him, he would be at a disadvantage. The god could smother his flames with his ice. Due to the nature of Bishamonten, he was inherently Issei’s natural enemy.

He could feel his body screaming at him to run, to flee away. If Issei died here, there would be no afterlife for him. His soul would be destroyed.

“Boost,” his sacred gear chanted. The sacred gear tried to increase his power but Issei stopped it.  Kiba had been able to create with his sacred gear something he thought he could not do, so why couldn't he do the same?

He grasped and directed the energy from his sacred gear to his body. He remembered the feeling of his skin mending together, of healing under the sacred gear of Asia.

He remembered this feeling and pushed the energy of his sacred gear toward his body not to strengthen him but to heal himself and the boosted gear followed his will.

The fire that ran through his veins increased in intensity surging through all of his body and burning and cleansing any injuries, any foreign energies.

It didn't matter that it shouldn't be possible. It didn't matter that Issei knew mostly nothing about how a body more precisely the body of a devil with the soul of a dragon worked. His fire healed him.

“Is this what you were talking about?” he asked the dragon that lived in his arm.

“The Tetragrammaton put on me even in death restrictions. There are things I can directly say or show you but saying that you can do so much more than with your sacred gear if you believe in yourself isn't really telling right?” the dragon answered him.

In his back, a new wing reappeared to replace the one that he had lost. It didn't matter that his body was scared. He would burn this fear.

It didn't matter if he was injured by the ice and frost of the god. He would make sure that anything hindering him is destroyed. He would burn everything on his path!

“ERROR: BREAKING OF THE PROTOCOLS, BREAKING OF THE PROTOC BALANCE BREAKER: FLAMES OF THE END!” 

The flames surrounded him and expanded in the sky, on the sea burning and in the air burning everything. The plot of land under Issei, the ocean under and gravity melted to nothing, creating a vacuum around the form of the floating boy. 

“You unlocked them?” the shocked voice of the dragon rumbled. “How did you do such a thing? Those flames, I had sealed them!”

“I don't know,” Issei answered honestly. He felt as if he could cradle the world itself in his arm as if he could crush the universe in his palm! 

He turned toward the shocked face of the god. He moved one of his arms as if he was leading a symphony and his flames rushed at the god.

The god copied him sending a wave of black frost and ice to counterattack. The two waves of elements met in the middle of the sky and created an explosion.

The explosion sent a shockwave creating Tsunamis under them bigger than a building. Boiling Mist took life in the sky poisoning the heavens. Those that would unfortunately breathe it would be meeting from the inside.

The god rushed at Issei.  He tried to skewer Issei on his spear, to puncture the flesh of the teenager.

Issei’s hand moved and caught between his palms the blade of the spear. With one movement, he pulled it at his side and the god followed only for a knee to crash against his bare stomach.

Ichor erupted from the mouth of the god but Bishamonten was not a warrior god for nothing. Even with the pain, he struck at the pawn, sending a headbutt in his face.

The headbutt crushed the nose and the cartilage under the skin of the boy but unlike the other times, the boy didn't move.

The god paid it back to the god sending a left hook in the face of the god sending him ragdolling toward the Ocean.

The skin of the god came close to the gigantic body of water and froze all of it. The god pirouetted in the air like a dancer ending on his two feet, gliding and skating on the continental mass of ice. The god with a flick of his will summoned his spear in one of his hands 

The blade of the spear was red as if it had been a weapon on the verge of being melted to be shaped into another one.

The reincarnated devil fell from the sky like a falling star, an inferno following and covering the heavens in a crimson hue.

The god used his authority over the ice to move and increase his speed. He was right to do so. 

A microsecond later, the right leg of the Gremory pawn crushed the spot he was standing instant before atomizing it.

The ice surrounding the boy boiled into nothing. The god sent a deluge of weapons made of black ice to the reincarnated devil.

Issei’s feet position shifted and the boy pushed sending himself flying toward weapons of black ice went at him.

The ice is the god may have been sturdy, stronger than titanium but it found itself useless against the flames inherited by the successor of the dragon who stole the concept of combination from the Abrahamic God himself.

Issei punched the air sending a shockwave that cracked the frozen ocean under them toward the god. The god with one slash cut through it.

With another one, he sent a flying blade in the form of the brown-haired boy. Issei backhanded it as if it was an annoying mosquito.

Claws of fire grew from the fingers of the boy. They rushed at the god burning everything in their way.

The god sidestepped them, skating and moving to the left. The boy’s arm moved and his claws followed going after the god in a vertical strike.

The strike was too quick for the Bishamontem to dodge. He knew this, so the god’s feet dug into the ice under him to ground himself.

He reinforced his spear coating it in star-extinguishing frost and struck with it against the flames as if it were a baseball bat.

The flames met the resistance of the ice and the spear of the god creating a sound akin to the lamentations of an ending world.

The ice all around him cracked before melting and boiling into nothing. The two of them were destroying the world whether they wanted it or not.

The ice of Bishamontem had frozen hundreds of millions of lives both animal and human, both mundane and supernatural.

The flames of Issei made sure that the bodies of the deceased would be rendered null. The flames of the boy had already melted in less than a minute more than half of the Pacific Ocean.

The spear of the god was able to protect him making the flames disappear as a consequence of breaking in two.

Issei's fist rushed toward the head of the god. The god moved it to the side, caught the two still-flying broken pieces of his spear and used one of them to stab the pawn in one of his knees.

A grunt of pain escaped from the lips of the brown-haired pawn as divinity-infused steel pierced his flesh and began to poison him.

The pain made him stay idle for an instant. Bidhamonten tried to use that instant it end the life of Issei.

The other broken piece of his spear flew like a star toward the face of Issei. Issei’s right hand moved trying to stop the attack. 

The strength of the god allowed him to pierce through the hand of the pawn. The blade of the spear was nonetheless stopped centimetres away from the face of the boy.

Issei opened his mouth and from it spewed a concentrated beam made of crimson flames. The fire beam consumed the blade of the spear, and the hand of Issei and took half of the face of the Japanese god.

It continued away from them like an ascending meteor piercing through the sky and dispersing flames and frost. 

“Do you think that this is going to stop me? I may die but I'll make sure to take you with me!” yelled the god before with one hand he pulled violently the broken fragment of his spear embedded in the flesh of Issei.

Black ice grew around the broken spear. The god’s arm moved directing the spear toward the Heart of Issei.

They were too close for Issei to dodge completely so instead of trying to do so, he chose to sacrifice his left arm.

The spear bit and cut through the flesh of his right arm sectioning it at the level of his elbow and destroying it at a cellular level. Issei ignored the mind-consuming pain.

It hurts so much and there was nothing else he wanted to do except make the unbearable pain stop.

His mind and his body would have given up if it were not for the fact that he had felt worse before. What was this physical and metaphysical pain before the loss of his parents? What was physical and metaphysical pain before the idea of leaving Asia all alone?

With his remaining arm, he sent an uppercut to what remained of the chin of the god breaking and destroying it. He extended fully his arm and sent the god flying into the sky over him.

The god pivoted in the air, snow and frost surrounding him, coating him to a point where it seemed they were more his flesh than anything else.

The crimson flames were still burning inside and outside Issei but they were deemer, less radiant. 

It was clear that whatever would happen in the following moments, the fight between the reincarnated boy and the Japanese god would end. Issei felt so exhausted like he never did before. It was as if every part of his body was weighted down by the universe itself.

“Don't hesitate!” the voice of the dragon in Issei’s soul roared. “Don't stop! Don’t give up! You will win As long as you do so! You are not fighting only for yourself! You are fighting for your dead parents, for your dead friends, for the woman you love!”

“BOOST! Chanted his sacred gear with what seemed to be thousands of different voices. All of his flames gathered from the sky, his body just to coat his right arm.

“SHOW THE WORLD YOUR MIGHT. SHOW THE WORLD THAT YOU ARE THE RED DRAGON EMPEROR ISSEI HYOUDOU! the voice of the Welsh dragon thundered.

Issei’s wings batted one last time using all of his remaining demonic energy to send him ascending as fast as lightning toward the dark ice tempest Bishamonten had become.

Issei’s fist and the transfigured form of Bishamonten met in the void between the Heavens and the ocean.

They touched and the world shrieked in agony. Frost and flames expanded around them dancing and destroying each other covering more than thousands of kilometres.

Issei’s presence near the icy form of Bishamonten was damaging him. All of his flames had been stripped away from his body to make sure to end the god. That made him more vulnerable.

The cold bit through the flesh of the boy turning blue-gray and making him lose all sensation. 

He could feel his body breaking, dying from the inside as the cold of the god froze and destroyed his flesh, his muscles and his bones.

He had stopped being able to breathe the moment his fist had clashed against the god. His dead skin began to turn black, to necrose but even then, Issei stayed confident in his victory, in his survival.

Only a fool would think such a thing. It seemed clear that the boy would lose to all except him. The reincarnated boy was not constricted by logic. He had faith in himself that he would win and his faith was rewarded.

Issei heard a familiar voice, her voice. “Ô you children of the land of the rising sun,” she spoke softly at first before her voice thundered in his soul like a divine decree.

You who had never been able to rise over your stations. You who never could fight to make this world yours. I gift your souls with potential. The strength of Every being that would fall because of you would become yours. I free all of you from the chains binding you since the dawn of time. I bless all of you with my fire!

“No, no, no, NO! Screamed the god over him his form reverting to a physical one. “WHAT KIND OF BLASPHEMY IS THIS!”

Issei could have sworn that he saw something crimson just like the president's power of destruction appear and plunge into his chest.

He used the opportunity that his king had given him. Emboldened, he moved and pushed even more. His punch broke through the ice of the god and continued piercing and wrecking through his flesh and heart to emerge to the other side. Issei pulled back his remaining arm leaving a hole the size of a basketball in the form of the god. 

“It shouldn't have happened this way,” the god whispered before his body blew up in thousands of blinding lights, lights that told stories, that tried to give him an understanding he refused to have.

He didn't want to understand the god. He allowed himself to close his eyes. He had done it! All the adrenaline and the determination holding his body together left and Issei began to fall.

“Don’t worry partner, I'll make sure you survive. It would be shameful if a god slayer died drowned don't you think? Would it even be right to call you a god slayer with what the Bael spawn did?” he heard the dragon muse before everything turned black for Issei Hyoudou.