Highschool DxD and Undertale are own by Ichiei Ishibumi and Toby Fox respectively while Fist of the North Star and Kengan Ashura elements are included as well
He kneels to the ground, hurt and injured from the battle. He looks at his opponent, a skeleton with a blue vest on and sees not a scratch on him. "Sorry kid but I'm just following orders."
"Hey don't sweat it." He said waving his apology. "I know a thing or two about orders. However..."
He stands on his feet and raises his hands in a battle position and even though he feels this will be a losing battle, he feels excited. "...Don't expect me to make it easy on you. If I'm going to die then I want to do it standing and fighting."
The skeleton just smiles as his eye glows blue and weird looking cannons appear behind him. The kid smiles as well and runs at his opponent as the cannon fires lasers that engulf him.
Issei wakes up in a fright. He breathes heavily, thinking about those nightmares. 'What is with these dreams? I've been getting them since I became a devil.'
Ever since he became the Pawn of Rias' Peerage, he has been having nightmares of another life. Training in martial arts, falling in Mt Ebott, fighting monsters, and even his death. Issei can't understand it because he never went to the mountain or an underground full of monsters. His confusion however is stopped when he sees the time. "Oh crap! I'm going to be late to crash the wedding."
He quickly dresses up in a orange shirt, black jacket, black jeans, orange running shoes and leaves his house, running to the wedding. Issei's buchou and king Rias Gremory is being forced to marry scumbag Riser Phenex who just sees her as a plaything to use. The Boosted Gear user is going to the wedding and stop it. Though he begins to daydream while he runs as he gets a nosebleed. 'Maybe Rias will give me a reward for saving her. Heheh.'
He is distracted as he bumps into someone, causing them both to fall to the ground. "Ah!"
"Who do you think you are- Wait…" The woman focuses on the man that bumps into her. "There you are!"
Issei opens his eyes and sees a woman he knows. "Isabela?"
Riser's Rook, known for wearing a mask that covers her right side, gets up and glares at the Pawn of Rias. "Come with me now!"
She grabs him by the shoulder and lifts him up. "Whoa! Isabela what the hell?"
"Master Riser sent me to capture you. He wants to make sure you don't interrupt the wedding." Isabela gloats as the Boosted Gear user glares at her until he notices something and his eyes widen. "Why are you looking at me like that, peasant?"
"What happened to you?" Issei ask which confuses her until she touches her face.
"M-my mask!" She cries out as she gets on her hands and knees to search for her mask. Issei stands stunned as he kneels next to her. He puts his hand at her shoulder. "Isabela look at me."
"No! Don't look at me! Don't look at my disgusting face!" She shouts in fear. Issei grabs Isabela's hands and move them away to show her face. It was in 2nd degree burns as her right side is red skin. It reminds him of the Phantom of the Opera. "Who did this Isabela? The only person I know that can control fire is…" Issei's eyes widened at the thought and rage overtook him. "That bastard!"
He gets up until she grabs his hand. "Please do not defy him." What was once a confident woman, is replaced by a scared and timid girl. "You will die by his hands."
Issei kneels to her and gives her the mask. "I don't care. He hurted you, that is something I cannot allow. You are too good for him."
He runs to the church with Isabela looking at the man with hope in her heart. 'Will he save us?'
The wedding of Riser Phenex and Rias Gremory begins as the groom and bride stand at the center. The Phenex heir has a smug look that he is about to marry the redhead bombshell while said redhead is saddened that she will be with a scumbag like him.
The reception is going well until…
"Now is there anyone here who wishes to object as to why these two should not be wed?"
*BAM*
The gates are force open and Issei enters the building with anger in his eyes. Rias is happy to see her pawn while Riser is disgusted at this peasant. "Tch! It would seem Isabela failed to deal with you. After I marry Rias, I shall punish that pathetic rook."
The Boosted Gear user runs to the groom and punches him in the face. "BASTARD!" Riser falls to the ground shock at his impudence. "Get up! We are going to fight here and now!"
The Phenex Lord gets up and orders the Devils. "Guards! Take this peasant away for laying a hand on my son!"
"Delay that order." Sirzechs stands in front of the reception. "I wish to see this fight."
"You cannot be serious Lord Lucifer!"
The brother of Rias shrug his shoulders. "If you believe in your son then he should win. If not and Issei wins then the wedding will be nulled and void."
"Fine! Riser, teach this peasant the power of the Phenex." Lord Phenex orders his son who gets up and is piss that he lay his hands on him.
The two find themselves in an arena, big enough for them to go all out. Though Riser just laughs mockingly. "This arena is unnecessary. I will end this in an minute."
Issei doesn't reply and gets in an fighting stance. In a second, his fists become a blur as he strikes Riser twice in the stomach. He kneels in pain and vomits from the strike. Riser gets up and sees the Boosted Gear on his opponent's left arm. 'When did he summon that damn Gear?! Was it just as he was hitting me?'
This confuses Rias and her peerage because they know Issei doesn't know any martial arts and uses instinct to fight. This mockery enrages Riser as flaming wings appear from his back and flies straight to Issei and summons a fireball at him but he sidesteps from the blast. He gets to his face but the Phenex heir creates another fireball and hits him, sending him a few feet away from him. Smoke is coming from his wound but doesn't seem to be in pain.
"Now die Pawn!" Riser shouts but he can't feel his right arm which dangles lifelessly and burning. "What?!"
"Before you hit me with that fireball, I soak my Gear in holy water and hit your shoulder's pressure point. Now your immortality is negated and you can die like any other man." Issei explains to the shock of everyone, especially Sirzechs and Grayfia. The wife of Lucifer looks at her husband.
"My love. That style, could it be..."
"I don't know darling. Let us keep watching and perhaps we will have an answer."
The heir of Phenex holds his limp arm and shouts at the peasant. "You cannot stop this union! This is for the legacy of Devil-kind! Rias Gremory is mine and there is nothing you can do to stop it!"
"I don't give a shit about that anymore." He admits as the heir's eyes widen at what he said. Issei then looks at Ravel and the rest of Riser's Peerage "I'm fighting for the women you abuse. I will free your peerage and give them the love they deserve."
Ravel is shock at what he said and looks at Isabela who is looking away. "Isabela, did he hurt you?"
"He has." She admits as she takes off the mask to show her burn marks. The Phenex daughter gasps and hugs the Rook. "I am sorry Isabela."
She feels guilty that she did nothing but the mask girl returns the hug. "It is okay. Issei will win."
"Do you believe he can free us?" Mira looks hopefully as Isabela smiles at the battle, at Issei beating Riser. "I know it."
Rias however cannot believe that her pawn doesn't care about her anymore and her hands begin to shake in rage. Her peerage vow to make Issei Hyoudou pay for his words.
"You piece of trash! I am a king! I am allowed to do whatever I want to those bitches!" The vile Phenex snarls but the Boosted Gear user powers up to finish this filth off. "Alright Ddraig! Time for our deal! Let us show them the power of the Red Dragon Emperor!"
"BOOST! BOOST! WELSH DRAGON OVERBOOSTER!"
Red armor appears and transform him into a knight. His power is increasing by every second. "Boosted Gear: Scale Mail!"
"Damn peasant!" He uses his other hand to launch a fireball which hits his helmet, destroying the left side of it but using the rockets now attach to the Scale Mail, Issei is launch straight to Riser's face. The Phenex heir's eyes widen when he appears in front of him and sees his eyes. He prepares to fire but is hit with a barrage of punches.
*BAM* *BAM*
"This is for everyone you hurted and abuse you piece of trash!" Issei declares as he unleashes a flurry of punches.
*BAM*
"Mira!" The Martial Artist remembers all the times Riser would yell at her, call her weak and useless.
*BAM*
"Shuriya!" The tan belly dancer was a slave that was purchase by Riser and use her for disgraceful acts.
*BAM* *BAM*
"Burent! Marion!" The maids serve the Phenex household for years but they were always treated like nobodies.
*BAM* *BAM*
"Ile! Nel!" The young twins remembers all the times Riser would touch them despite their age, making them scared to be around him.
*BAM* *BAM*
"Ni! Li!" The Nekomata sisters were almost executed along with other Nekomatas for Kuroka's crime but Riser made them pawns only to beat them and pull their ears, calling them freaks.
*BAM*
"Xuelan!" The Chinese national wanted to be stronger so she went to Riser but he would always say that she was weak because of her gender.
*BAM*
"Siris!" The Zweihander user was a soldier from a European country that was kidnap and force into Riser's Peerage.
*BAM*
"Karlamine!" The Knight was loyal to Riser but he never respected her no matter what she did.
*BAM*
"Mihae!" The Priestess use to take care of a temple only for it to be destroyed and Riser just so happen to be around to revive her. Now she knows the truth.
*BAM*
"Ravel!" The Phenex Heiress can remember the time her brother Riser would look at her as if he wanted to touch her which frighten and disgusted her.
*BAM*
"Yubelluna!" The Bomb Queen didn't want to be part of Riser's Peerage but her Devil family just sold her to him for money.
*BAM*
"And must of all, Isabela!" The scarred woman smiles at the man she would be proud to call her king.
*CRUNCH*
"Hokuto: Hundred Crack Fist." The last strike breaks Riser's nose and he holds his mangle face. He goes in his rage and yells at him. "Do you think you can end me trash!? I am the Phoenix itself! You may be from that clan but I will kill you!"
Within Issei's soul, Ddraig is shock by the attack. It is a technique a previous user used. "Interesting. Are you his descendant Issei Hyoudou?"
The Phenex heir feels his face breaks down and convulse. Before he explodes he says these last words with hatred in his voice. "Damn you Kure filith!"
*SPLAT*
"Winner by Death, Issei Hyoudou!"
Issei looks down at the corpse that will not regenerate and feels confuse by what he said. "Kure..."
He turns around showing everyone his eyes, black sclera with white pupils. Many reactions are shown: Ravel and the others are cheering as they run into the arena and hug him, Rias and her peerage are shock, Lord Phenex is gripping his chair enraged, and Sirzechs and Grayfia realize his identity.
As he walks away, he cannot help but be curious about that name.
"Why does that name seem familiar?"
Next Time- Consequence of the Phenex Slaying
"You will pay commoner!"
"You are my pawn Issei!"
"Thank you Issei."
"If you want my head then do it yourself!"