Sins of the Father

Izuku and the rest of the Injustice League were looking at the newly built weapon, or I.A.M.M.A.D., Mei was also covered in cybernetic armor put her hand on the switch, "The machine is ready when you are."

Izuku looked at his watch smiling, "Let's start the show!"

Mei then turned on the machine which the clown that was on the building's head came off to reveal the machine pumping out green gas into the air. The league walked to the window with binoculars looking to see people looking at the green clouds and gas coming at them. The people started running away and getting in car. Scarecrow chuckle, "Car ACs won't filter the gas, the gas is designed to go through any air filtration system."

Then they saw people falling victim to the gas, one person started stabbing people while laughing and another started using their quirk to destroy anything nearby them. Izuku smiling, "It's perfect."

The heroes, police, and military were heading over to Izuku's hideout until they saw the gas coming at them. All Might then threw a 'Texas Smash' to blow the gas off of the way to make a clear path to Izuku. Izuku looked at All Might coming, "He is coming Nana!"

Nana grunted, "I hope he stops you, you evil little shit."

Man Bat punched her face hard, AFO chuckle, "Let the mouse walking in a lion's den."

Izuku then nodded at his league which they left to their posts, AFO standing next to Izuku with Nana on a leash like a dog, "Keeping All Might separate from the rest. I like that you are giving such a stage to perform on."

Izuku giggle, "Even if you die, you win and I win in the end."

AFO looked at All Might coming, "I wish I was there at the beginning."

Izuku turned to AFO, "What?"

AFO handed Izuku a letter, "You might want to read that later. My last advice to you is that… if you want something then take it."

Izuku looked at him confused then smiling, "Go get him, Tiger!"

AFO laughing, "I will, my boy!"

All Might then saw two figures in front of him, he got a closer look to see All for One and a woman with a collar on her. AFO chuckle, "It's been a while… All Might!"

All Might charged at AFO but AFO used a quirk to block his punch, then All Might just back, "All for One!"

AFO looked at the woman, "Hey Nana… your successor is here."

Nana then looked up to see Yagi, Yagi was in shock, "M-Master."

AFO smiling, "Deku gave me her bones to bring her back from the dead. She is the real deal, not a clone, not an illusion, but the real Nana."

Yagi looked at AFO pissed, "I will save her unlike last time!"

AFO laughing, "By yourself!"

Yagi turned to see the other heroes, police, and military were being attacked by the Injustice League and their grunts. AFO stretched his arms out, "I'm not letting you fight with backup and…"

AFO made a blade with his arm to slice off Nana's head off, "With your full power and rage."

Yagi snapped to fly at AFO, but AFO grabbed both of his hands which caused an earthquake that shook the entire city bring building down. Izuku's base was earthquake proof so his machine was still running without damage. Izuku watched the battle in front of him then he got curious about the letter which he opened it up to read it.

Yagi then punched AFO hard enough to send him to the ground breaking his mask. Yagi was deflating and reaching his limit, until AFO laughed a little more, "You know All Might, I'm going to give you a secret about myself…"

AFO shot his 'Air Cannon' combo at him, Yagi was flying back until he had a flashback of Nana and her decapitation. Yagi clenched his fist then jumped back to the battle, Izuku at his base reading the letter and holding a picture of his mother and a white hair and grey eye man. The letter read:

Dear Izuku,

I'm dying and after this fight with All Might that will lead to my death, I want you to know that Hisashi Midoriya isn't your biological father…

Yagi stood on his two feet which AFO giggling, "Hisashi Midoriya isn't Izuku's biological father."

Yagi froze in place, "What?"

AFO looked at him smiling, "You see his mother had an affair with another man… and that man is me!"

Izuku reading the letter:

I'm your biological father, your mother and I had an affair. I was going to take her away from her arranged marriage from Hisashi but then All Might and I had a fight. The result of the fight led to injuries that my quirks cannot heal.

Izuku looked out to the battle in shock, AFO smiling, "His Resurrect quirk is one the quirks that I give him before you separated us."

Yagi raised an eyebrow, "Quirks?!"

AFO raise his arms to the air, "His main quirk that he was born with is All for One!"

Izuku looked at the letter:

Resurrect and the longevity quirk are your quirks. Your main quirk that you were born with is All for One, I was low of funds because of the medical equipment cost to keep me alive to see you again. The doctor lied to you to protect you from All Might and his successor because like One for All is destined to fight All for One, All for One is destined to fight One for All to survive. It's like two alpha predators in the same ecosystem always clashing each other.

AFO looked at Yagi, "I will die and you will lose the last bit of One for All in your body. My son and your successor are destined to fight each other like me and your predecessors."

Yagi clenched his fist, "I guess the apple didn't fall too far from the tree."

A circle of the gas and debris formed around AFO, "Even though I didn't raise him like I wanted to… he has turned out better than I have ever dreamed of. He is beyond worthy of inheriting my title 'Symbol of Evil' and as his father… I'm excited by what he will do!"

Izuku tearing up as he read the letter:

I'm sorry I wasn't there for you and your struggles, but I'm proud of you. Your ideals of giving the world the villain it so badly deserves; I couldn't help but smile. You have surpassed me in every way, now that you are equipped with the knowledge of your real quirk. I am leaving behind my more than 200 years of research of quirks and their combos, information of people with quirks you might be interested in, and my strongest nomu that I have not named yet. I will let you name that one, I can't wait to be reunited with Inko.

Love your father, Komatsu Akikazu

Izuku looked at the picture then to AFO who was fighting Yagi, "My real name is Komatsu Izuku… I…"

Izuku started have flashbacks of his time with AFO, as he encouraged him, have conversions with him, giving him the longevity quirk, helping him break All Might, creating the strongest nomu with him, and now looked at him about to win against him. Izuku with tears rolling own his cheeks, "I… I forgive you… Dad."

Yagi then punched AFO with his strongest punch, 'Good-bye All for One!' "UNITED STATES OF…"

Yagi punched AFO to the ground, "SMASH!"

Yagi was now in his normal weak form, 'Good-bye… One for All'

AFO chuckling weakly, "It's your turn…"

Yagi saw AFO pointing at Izuku, "Deku: Symbol of Evil."

AFO coughed out some blood then Yagi checked his pulse to find that he was dead. Yagi started giggling, then laughing in joy. Yagi then started kicking AFO's body then punching it, Izuku talked in his earpiece, "We did it… begin phase two."

Shinso had control of some military men got up to walk back while Koda rode his elephant back. Koda reached his hand out to Shinso, Shinso took his hand to jump on the elephant. Neito used a copy of Captain Celebrity's quirk to fly back, Ibara made a plant monster to fly her back. Mei use her suit's jetpack to fly back, Sato ran back with Toga, Momo, and Jiro on his back. Shoto smirked at the heroes before making a tornado with his quirk to destroy whoever was left of the raid. Man Bat was eating the flesh of some of the heroes then he flew off with a body to eat later.

Aizawa saw Yagi laughing while beating up the body of AFO which he came over to kick him off, "What the hell is wrong with you?!"

Yagi looked at him, "I finally did it, after centuries of this bastard. I finally was the one to defeat him for good."

Sir Nighteye came over, "But he won in the end, you no longer have One for All and you are broken mentally."

Aizawa and Sir glared at Izuku which Izuku took his face off to reveal is skinless face smiling back at them. The two looked to see that they lost their whole team to raid them with and their machine is pumping the gas into the air. The turned to see the military men with gas masks laughing like madmen and killing each other. Aizawa and Sir grabbed Yagi to retreat, Izuku was laughing as they retreated.

Izuku then heard someone coming in which he turned around to see a teen about two years older than him with blonde hair and blue eyes. Izuku smiling, "All Might's successor, Lemillion… or Mirio Togata."

Mirio's eyes widen, "How do you know?"

Izuku put his face back on, "You see Mirio, All for One and I have a hobby that we share… we love quirks!"

Izuku revealed a remote in his hand, "All for One and I made something that is design to kill every user of One for All, if he were to die."

Izuku pressed the button which a cage opened up, Mirio heard growling and stomping. Izuku pointed at the beast, "This nomu is unlike any nomu that the world has ever seen. This nomu is made from over 300 heroes, villains, and civilians… I give you…"

A huge monster came out standing on two legs with crystals and horns coming out of his body, gleaming red eyes, grey skin, and it was 5 times Mirio size. Mirio looked at the monster in fear and Izuku yelling, "DOOMSDAY!"

The monster then roared so loud the windows of all the building in its one-mile radius broken. As Sir, Yagi, and Aizawa were running; Sir's glasses shattered which the glass got in his eyes. Aizawa looked back to hear the roar, "That doesn't sound human, what is going on."

Mirio looked at Izuku, "This is so wrong, how can you use the lives of people to create this thing."

Izuku laughing, "I will send a video of how I did it to your address if you survive this."

Doomsday looked at Mirio then Izuku shouted, "Go get him, Doomsday!"

Doomsday threw a punch at Mirio but Mirio phased through it then Mirio use 30% of One of All to punch Doomsday. But Doomsday didn't flinch or move, Izuku smirked, "Doomsday don't have one shock absorption quirk, but multiple and different versions of shock absorption."

Doomsday grabbed Mirio to throw him out the window, Mirio landed on his feet but Doomsday came in flying at Mirio. Mirio phased to not get hit but Doomsday's punch created a crater to destroy everything in a one-mile radius. Mirio unphased himself to see the destructive power of Doomsday, "Oh… my… god."

Izuku felt the building collapsing, "Well I need a stronger building, oh well…"

Izuku then went over to grab a jetpack that Mei made for Izuku's escape. Izuku then flew out of the building as it collapsed, the machine then stopped producing gas but Izuku really cared about Doomsday because it was extremely valuable. Shoto called up, "Deku, the packages have been delivered."

Izuku in a dark twisted tone, "Good, put them in my office."

The heroes who survived Doomsday's earthquake causing punch got up and out of the rumble to see Mirio fighting Doomsday. Aizawa and Yagi saw the beast as it shot lasers out of his eyes. Mirio dodged the lasers to then throw a steel rod at Doomsday which it penetrated its skin but then Doomsday absorbed the rod and the wound disappeared. The major in the squad of the army with the heroes shouted in his radio, "We need an airstrike NOW!"

Then two planes came over to shoot missiles at Doomsday and a giant cloud of smoke cover the monster, as the smoke cleared, they saw Doomsday dead. Mirio sighed in relief but then Doomsday regenerated to full health then it's skin because grey as steel. Mirio, the major, and the heroes were in horror by Doomsday. Izuku laughing, "One of Doomday's most valued quirks, Evolution. It can evolve to suit their surrounding and for their survival, he can never die! He will just be close to death, then regenerate, and evolve to where it wouldn't die the same way twice."

The major got close to his radio, "Give that monster everything those jets can offer."

The two jets came back but Doomsday opened its mouth to shoot plasma at the jets to destroy them both. Mirio shouted, "One for All: 100%"

Mirio punched Doomsday with everything he had but Doomsday was unaffected and Mirio broke his arm. The major said, "Drop a nuke on that thing!"

Sir got next to the major, "No! We have people here!"

The major shouted, "We have an unkillable monster here as well, we must drop the nuke."

Aizawa shouted, "Mirio! RUN!"

Mirio heard Aizawa which he used his quirk to get away from Doomsday with getting killed. Doomsday was about to chase him but Izuku said, "Doomsday wait!"

The beast stopped then Izuku saw the plane with the nuke which Izuku pointed at the plane, "Snack."

Doomsday growled as the plane came, the plane dropped the nuke which it was coming to Doomsday which Doomsday jumped in the air to eat the nuke. The major and the heroes were in shock that this monster just ate a nuclear bomb. The creature came back to the ground roaring and Izuku laughing, the major said, "No way… that thing just ate the nuke."

Aizawa in horror, "What is that thing?"

Mirio said, "According to Izuku, it's All for One's strongest nomu made of over 300 quirks."

Yagi thought to himself, "Such power, if I was in my prime… even I wouldn't be able to stop that thing."

A portal opened behind Izuku and Doomsday which Izuku waved, "See you soon… Mirio."

Then the two entered in the portal to Izuku's new base with new plans and for Izuku to learn to use his real quirk.