The Birth of Fear
"Life without fear is meaningless." - Scarecrow
15 years ago
It was another night for the pro hero Midnight, she had stopped a couple of muggings and captured a few small-time villains. Safe to say she was a little tired for the night, but she was going to stop by Eraserhead's patrolling area first to check on how he is doing. She was on her way until something started come at her from behind, she barely dodged the first attack which the attacker said, "Not bad, as I expected from 18+ rated hero, you don't let up."
Midnight asked, "Who are you and why are attacking me?"
"Just a guy with a job, nothing personal." The attacker responded. The attacker then threw some blades at her, but she dodged them except one which gave her an advantage. She activated her quirk, but the attacker wasn't be affected by it which she asked, "Why don't you go to sleep for me."
The attacker said, "Sorry, I have a quirk that makes me unaffected by any gas that kills or knocks me out."
Midnight used her whip and the attacked kept dodging; the fight was just a series of attacks and dodges until the attacker made a fake opening. Midnight took the opening but then the attacker knocked her down and use it to pull out an empty syringe and took Midnight blood. He then said, "It's been fun Midnight, but I got what I was paid for."
The attacker ran off into the shadows, Eraserhead found Midnight and asked, "Nemuri, are you ok?"
Midnight said, "I'm fine Shota, the attacker didn't hurt my too badly, he did take some of my blood though."
Eraserhead said, "I wonder who would want your blood?"
An hour later at a warehouse somewhere
The attacker went inside the warehouse to drop off the blood and get his pay so he can leave. The warehouse was dark, it had chambers with people and monsters in them, he was wondering why someone wanted Midnight's blood, but he chose to not question his client. He walked until he found his client in his desk and hi client said, "Did you get what I paid you for?"
The attacker showed the syringe full of blood which the man said, "Excellent, as for your payment."
The man gave the attacker a suitcase full of money and the attacker gave the blood to the man. When the well-paid attacker left, the man said, "With this blood and this DNA modifier, I will bring to life a new symbol, a symbol of fear."
5 years later
The child that was created that All for One named Izuku, was learning to control his quirk so he couldn't hurt Tomura and Kurogiri, as well as other allies. All for One made the child have green eyes and hair, which Izuku asked, "Why did you give me green eyes and hair, Sensei?"
Sensei said, "Because life without fear is meaningless, green is the color of life, and in a way, you are the one who will give meaning to the lives of society."
Izuku grew up to learn that his quirk makes a greenish yellow gas that put people is a state of fear, he is unaffected by his own gas, and in his off time he read books on chemistry, psychology, and psychiatry. Sensei liked that Izuku was studying the right subjects that would help him and his quirk to grow. Izuku then learn that he can change the intensity of the gas putting people into a nightmare induced comas and make people so scared that they will commit suicide. Over the years Sensei started to see Izuku started to show his mother's sadistic side, which Sensei was proud of the most because it made it to where he shows no mercy to his enemies. When Izuku trains with the nomus, which Sensei though they were empty emotionless shells, Izuku showed Sensei that they still had a sense of fear which impressed him the most. Izuku was to build muscle, constantly study to improve himself, but the most important thing was to become the Symbol of Fear.
Present day
Izuku was a decently known villain that no one really knew about, because he mostly did his work in the underground, he would use his quirk to make thugs and small-time villains join the League of Villains. Izuku was a teen, who was the living embodiment of fear which was Sensei's intension when Sensei told him of his origin, Izuku said, "So I'm the son of Midnight, that neat I guess."
Sensei asked, "You think that it's neat, not sadden that your mother don't know you exist?"
Izuku said, "Well I don't know really if people know I exist, all I care about is that I will for fill my role as the symbol of fear, and to bring society fear."
Sensei laughed in happiness that Izuku was ready for Tomura's plan to attack UA where it hurts and his first steps to destroy the hero loving society. Tomura and Izuku always saw each other as bothers, they saw Sensei like a father, and Kurogiri like a second father. Izuku had a hobby of improving his villain outfit (I'm to lazy to describe it so it's the same design as Scarecrow from Arkham City but with green eyes and a scythe) making it fire-proof and other things as well. His syringe gloves continue a form of his quirk that puts people in a nightmare induced coma, if he was fighting someone like Eraserhead, and he wielded a scythe which he is shown to be skilled with. His other hobbies would be reading chemistry, psychology, psychiatry, and experimenting his new gas combinations on people who were chained up in the basement. He would make his gas using his quirk then combining it with other compounds to make new fear gases that were either make a weaker or stronger version of his gas, which he would put them in gas grenade containers. Izuku was know in the underworld as Scarecrow because of his outfit, but people feared him to a point, where they gave him whatever he wanted which Izuku found it satisfying that his dominates doesn't have to be shown for people to do whatever he asked for.
Two days before the USJ
Tomura had recruited some thugs and grunts from Giran, but Tomura thought is wasn't enough and asked Izuku, "Can you bring me some more recruits please, Izu-chan?"
Izuku, in his outfit, looked at his brother and said, "Ok, I'll be back in two hours."
In two hours Izuku bought in about 150 more thugs and grunts, which made the league have about 250 disposable grunts at in Tomura's hands (this may or may not be an unintentional Tomura hand joke) to use at the USJ. After Tomura made his speech about the nomu should be able to kill All-Might, everybody left which led Izuku to go back to his room to prepare for tomorrow.
Izuku looked at the roster of the entire school, then he saw Midnight's face which he stopped and said, "I guess I'll be at the school where mom teaches at, guess I'll just leave a note or message for her."