A/N: Rated T for coarse language.
Contrary to popular belief, Izuku Midoriya is actually 30 years old. Izuku blamed his genes for giving him a babyface and making him short. People think he's actually a high schooler.
He lost count of how many times the bartenders and bouncers thought his ID was fake.
So when he heard UA was letting quirkless examinees take the Entrance Exam this year he couldn't resist their offer.
This was his only chance to become a Pro Hero.
Aizawa was intrigued when he found out he would have a quirkless student in his homeroom class this year. He almost expelled him during the Quirk Apprehension Test but he proved his potential with his maturity.
However, throughout the school year, Aizawa sensed there was something off about Izuku. For starters, Izuku reminded him of how high schoolers acted back when he himself was a student.
When he became a teacher, he noticed the high school culture changed drastically. He figured Izuku probably learned that behavior from binge-watching too many old sitcoms because according to his records, Izuku was homeschooled his entire life prior to high school.
Aizawa later suspected Izuku must have some sort of secret mindreading quirk because after he made that observation, Izuku immediately acted more like his classmates.
Aizawa figured Izuku was probably a psychopath or depressed. He hoped it was the latter. He made a small note in his planner to talk to Inui about it.
He sighed in relief when he saw Izuku become friends with Ochaco and Tenya.
"Izuku Midoriya. Please come down to the Principal's Office." A Female Voice said over the intercom.
Izuku's eyes widened. "Uh oh."
"Psst. Midoriya. What did you do?!" Hanta said.
Izuku shrugged.
Aizawa told him to come to the front of the class to get a hall pass.
Izuku walked down to the Principal's Office. He was nervous. He was worried Nezu would see right through his charade.
"Hello Midoriya!" Nezu chirped.
Izuku smiled.
"Maybe I'm not in trouble? " Izuku thought.
"Oh no, you are definitely in trouble!" Nezu said passively-aggressively.
Izuku gasped and wondered if he said that out loud.
"Ooh. I'm not a mindreader, you are just very expressive. Please take a seat." Nezu explained.
Izuku did as told.
"So Midoryia, I have been looking through your records and I noticed something peculiar." Nezu said.
"Huh?" Izuku said.
"Apparently, you graduated from high school thirteen years ago!" Nezu said.
Izuku dropped his jaw. "What do you mean-"
"The Gig is up! I already know you faked your records. I'm surprised it took my system a long time to sense it. I'm kind of impressed." Nezu explained.
"You do realize you could get arrested for this?" Nezu questioned.
"I-" Izuku stuttered.
"You intrigued me, Midoryia. You were willing to go through high school again just to become a Pro Hero. Let's strike a deal! " Nezu said.
Nezu decided he will let Izuku continue his stay at UA because of how chaotic his situation is. He decided to use Izuku to test how well the teacher staff cared for their students.
A few weeks later, Shouta became more puzzled after he and Toshinori had a Parent-Teacher Conference with Izuku's mother Inko about students moving into the dorms.
There was something off about her too. Shouta is now worried there is something going on at home. He decided to bring out the big guns and called an old friend.
"Hey Naomasa." Shouta said.
"Ooh. What's up Sho?" Naomasa said.
"Can you do a background check for me?" Shouta said.
"Um…"
Aizawa can hear typing in the background.
"What's the name?" Naomasa said.
"Izuku Midoriya." Shouta said.
Naomasa quickly put the name into the police's database.
"Izuku Midoriya. 30 years old. Born July 15. His record is pretty spotless except for some parking tickets."
"Wait, what? Did you put in the right name?!" Shouta said.
"Yeah. Izuku Midoriya. I-z-u-k-u. M-i-d-o-r-y-i-a. Right?" Naomasa said.
"Can you send the police record through the Hero Network App?" Shouta asked.
Aizawa pulled out his agency-issued smartphone when it vibrated and pulled up Izuku's file.
Shouta dropped his jaw. His world came crashing down around him.
"Is he a suspect in a case you are doing?" Naomasa asked.
"Naomasa...he's my student." Aizawa explained.
"Wait, what?! You meant an old classmate right? You guys are the same age!" Naomasa added.
Shouta paused when he realized Izuku must be the UA Traitor.
"I...I gotta go!" Shouta said.
"Sho! Wait-" Naomasa said.
Aizawa hung up and quickly dialed Nezu's phone number.
"Hello?" Nezu said.
"Nezu! It's about Midoriya! I think he's the-"
"Ooh. I'm surprised you found out so soon. I thought Midoriya was good at giving everyone the slip."
"Wait...you knew he was the traitor?!" Aizawa questioned.
"Traitor?! I thought you were calling about him pretending to be a teenager." Nezu answered.
Aizawa pinched his nose. He was so done.
"Of course. Of course, Nezu would allow this!" Aizawa thought.
The next day, Nezu asked Izuku to come meet him before school.
He was thrown off guard when he saw Aizawa there as well.
"Um…" Izuku stuttered.
"Problem Child, the jig is up! Or should I say...Problem Man?" Aizawa said.
Izuku gulped.
A few minutes later, Izuku explained why he was pretending to be a teenager.
Aizawa facepalmed himself and groaned.
"This is the Hero Commission's fault. There should be other ways for people to become heroes even if they didn't do the Hero Program in High School." Aizawa said.
"So...can I remain in your class?" Izuku asked.
"I was already on board but since Aizawa is your homeroom teacher I say he can make the final call." Nezu insisted.
Aizawa hummed while he thought deeply about this situation.
His left eye twitched when he saw Izuku making a puppy face.
"Uh Uh. You're a grown-ass man! It's not gonna work on me!" Aizawa snapped.
Izuku's pouted even more.
Aizawa sighed.
"Fine!" Aizawa whined.
Both Izuku and Nezu cheered.
"But if I find out you have any ill-intent towards any of my students I will make sure you will never become a hero!" Aizawa threatened.
Aizawa crossed his arms in frustration. He kind of saw Izuku as his own son.
"Is he now my little brother?" Aizawa thought.
Aizawa facepalmed himself again and groaned.
He wasn't being paid enough for this.
A/N: Since Izuku was born 15 years earlier it would mean Inko was around 55 or 56 in this story.