Chapter Text
Mates Through Time
Chapter 1
It was the first day of class at UA Academy. The only thing on Shouta’s mind was how sleepy he felt. Being tired was his norm, so he expected it to be an uneventful day with a brand-new class of teenagers. At least, that’s how it should have been—but he quickly realized just how wrong he was.
He saw bright green hair, freckles, a big smile, and sparkling eyes.
Shouta turned even paler than usual, the color draining from his face. Why was that boy there? It couldn’t be him. How? The teacher was stunned—why was Izuku there, and wearing a student uniform? Searching for an explanation or hoping he was just mistaken, Shouta looked over the group of teens. The green-haired one was chatting with two others—one blond, the other with red and white hair.
The teacher looked for anything out of place about the boy, but everything matched. Even—much to his dismay—his scent. When the wind blew, Shouta caught a familiar smell of rain and mint. It was fainter than he remembered, but unmistakable. The same scent. The same omega.
Shouta took a deep breath, his knees weakening as if about to give out. But then it hit him—this Izuku was younger than he remembered.
This Izuku wasn’t his Izuku. He was far too young. The Izuku Shouta remembered had been 21 years old. Why was there a 15-year-old boy with that same scent, ten years later?
Reeling from the realization, Shouta pulled himself together and went to class. During roll call, he learned that the young omega he thought he knew as Izuku Arakawa was listed as Izuku Midoriya. So not only was the age wrong—so was the last name.
When the final bell rang, Shouta went to find his pack. He needed help.
That night, at his apartment, Hizashi and Nemuri came over. They’d been his pack since high school—his friends and the people he trusted most. They sat at a small table with beers and snacks. Even though Shouta had called them, his eyes stayed fixed on the floor, as if the corner of the room held some secret truth.
“Shouta, just say it. We know something’s wrong. We’ve worked together for a long, long time, and not ONCE have you asked us to celebrate the start of a new semester,” Hizashi said, loud as usual—subtlety had never been his strong suit.
“Izuku.” The name was all Shouta could say.
“The one in Class 1-A?” Nemuri asked gently. Then, in a near whisper, added, “Or… your mate?”
He answered without looking up. “He’s my mate. He’s Izuku Arakawa, but at the same time he’s not. But his scent—it’s his scent. But he can’t be my mate… Can he?”
The realization that his student was in fact his mate was more than Shouta could process—now or ever. It had been five years since the last time he saw Izuku. Five years since they had met, grown close, fallen in love, become mates—and five years since the omega had disappeared.
Shouta could barely remember the first few days after learning that Izuku had “left.” It was like a haze, as if he hadn’t really been present. He didn’t remember events clearly, just a bitter, acrid scent. Hizashi had dragged him into the shower, forced him to eat, to drink, to leave the apartment. According to his friend, it took nearly a month for Shouta to return to some kind of normal. Shouta only knew that his turning point came when Nedzu gave him a letter written by the omega, along with some of his clothes and a blanket that still carried Izuku’s minty scent.
The alpha felt like an omega when he received those items, wanting nothing more than to build a nest with his mate’s scent. But he needed to function again. So he carefully separated the clothes, storing them in vacuum-sealed bags to preserve the scent for as long as possible. He cut a small piece of the blanket and made it into a handkerchief he kept with him. It comforted him enough to return to his routine.
Shouta’s instinct was to skip class that day and go home to process everything. He felt dizzy, his head ached, and his breath caught in his throat. But he took a deep breath and did what had to be done—even if his eyes never left the green-haired boy.
That night, his pack came to comfort him, when he was finally able to gather his thoughts enough to explain what had happened. Hizashi and Nemuri were as shocked as he was, but the resemblance between the boy they had met five years ago and the student was undeniable.
“Shouta… and the letter?” Hizashi asked quietly, which was odd in itself.
“Still as mysterious as it was five years ago,” the dark-haired man replied, placing the letter on the table. He knew it by heart, every word—he had lost count of how many times he had read and tried to decipher it. But it never revealed more.
The letter, written in clear, elegant handwriting that matched its author, read:
“I’m sorry.
I asked Nedzu-sensei to give you this letter after I left. Shouta, I can’t give you any answers. I needed to go home. I really can’t stay.
Forgive me.
Take care of yourself, Shouta. I hope you can forgive me.
I love you.
Izuku.”
A simple letter. Just an apology—nothing more, nothing less. No explanation, no clue where Izuku was, no hint of when they might meet again. Shouta had often thought it would’ve been better if the letter had never been written. Knowing that Izuku had left him hurt. But he also knew that without the letter, he might have gone mad searching for the omega. Of course, he had tried to find him—but it was impossible. Eventually, Nedzu-sensei made him stop.
“Nedzu-sensei.” Shouta’s eyes widened. “How could I be so stupid?” he shouted, slamming his fist on the table.
“What?” Nemuri asked, startled.
“Nedzu. He was always so secretive about what happened. If anyone has answers, it’s him. Izuku went to him when he first arrived at university. He had the letter. He was the one who convinced me to stop looking.”
“But Shouta, you’ve questioned Nedzu again and again. Why would he tell you anything now?” Hizashi asked, clearly discouraged.
“Because Izuku is back at UA. He’s under Nedzu’s care again. Whatever they were trying to hide—it has to come out now.”
A new energy surged through Shouta. There had to be answers. He needed something solid to hold onto so he wouldn’t lose his mind. Especially now that his mate was a teenager again—and his student. He needed something real to keep him from doing something reckless.
To his relief, the next morning, Nedzu was waiting for him.
“Are you going to tell me the truth now, Nedzu-sensei?” Shouta asked, his voice sharp like venom.
“Aizawa-sensei, no need to kill me. Now there’s no way around it—I have to tell you the truth. The real question is: will you believe what I’m about to say?”
“That depends. Will it make sense?” he hissed, the murderous rage still burning inside.
“It won’t. But listen anyway,” Nedzu said, his tone steady, full of his usual confidence. “Izuku Arakawa is indeed a false name. Izuku Midoriya is the same Izuku you knew.”
“So the boy really is him.”
“Yes. He is the same person…” A pause. A deep sigh.
“But he’s not the same yet,” Shouta finished. “That much I’ve figured out. His scent—although it’s the same—hasn’t matured. He’s not quite him yet…”
“By my calculations, it will take about five more years for him to become the Izuku you knew,” Nedzu added slowly, choosing his words carefully. “So what happened is going to happen in five years for Izuku… while for you, it already has.”
Shouta tried to keep up with Nedzu’s words. It couldn’t be true—but it was. He knew the older man wasn’t lying. Nedzu always told the truth. And besides, such an absurd lie would be foolish coming from someone as intelligent as him. The air around him seemed thinner, harder to breathe.
“Well, according to Izuku, he suffered an accident in the university lab. The device they were working on was meant to transport people through space—teleportation—but it ended up sending him ten years into the past. That’s when you two met,” Nedzu explained slowly, calmly, waiting for Aizawa’s next question.
“Why didn’t you tell me? Why didn’t either of you tell me?” Shouta’s voice was strained, angry. His chest felt like it was going to explode. It took all the self-control he had not to storm off and confront the omega—no, the teenager. He held on to the little logic he had left; the boy would just be scared and have nothing to say.
“Because of the potential effects on the timeline. Izuku never told me details. He’s too cautious to spread future information. The false name was meant to stop you from looking for him. Try to imagine how it would have affected you, Shouta, if you’d found a ten-year-old child instead of your Izuku. He wanted to preserve the timeline.”
“But…” The alpha tried to think calmly, the irritation rising again. He could’ve handled the information and still preserved the future Izuku was trying to protect. But no—the real issue wasn’t just the omission. “Why didn’t he stay?” The question slipped from his lips, though it was meant to stay in his head. He hadn’t wanted Nedzu to answer—but he did.
“Besides the implications of a temporal paradox, he knew he would be pulled back eventually. The adjustments he made to the anomaly machine were meant to help the colleague who caused the accident. And… I dare say, he liked the life he was living.”
“And now?” Shouta felt dizzy. It was true—he knew it was. His inner alpha screamed in pain and anger: Rejection. The omega had rejected them. Shouta thought just like his instincts—if Izuku had chosen to return home instead of staying with him, then the bond truly had been severed. The apology in the letter wasn’t enough—not even close.
“Now, Aizawa-sensei, we teach. We guide our new students. And we remember that what has happened to you, has not yet happened to young Midoriya.”
Shouta could only remain silent. There was no way out of this. He would have to swallow what he felt. That storm of emotions had to be buried and wait. He would have to wait another five years before meeting his Izuku again. Watching as a teenager slowly became the man he loved.
He left Nedzu’s office, slamming the door behind him and swallowing the growl that threatened to rise in his throat.
Maybe Izuku really would grow into a good man. But by then, the alpha might have already gone mad. He swallowed the bitterness, the rage, and the sadness—and somehow managed to survive the day and face a classroom full of teenagers.
------
The first time Shouta Aizawa saw Izuku was at university.
He had been standing there, staring at the dormitory entrance. His messy green curls and dusty, wrinkled clothes stood out. Shouta remembered perfectly the oversized sweatshirt with an All Might design and baggy, high-waisted jeans. His first thought was simply: he’s beautiful. But what really floored him was the scent. A mix of mint, rain and home. It was delicious. Shouta knew immediately—it was the best scent he had ever experienced. He had to get close to that omega. He needed to be with him. His inner alpha screamed: Omega. My omega. It’s him.
As he approached, another student got to the omega first. Aizawa growled quietly, forcing it back down his throat. He overheard bits of their conversation—it sounded like flirting. The moment the other boy placed a hand on the green-haired one's shoulder, Shouta felt something inside him snap. He quickly stepped between them.
“That’s enough,” he said, his tone calm, firm, commanding—like a quiet threat. The other student backed off immediately with a hiss of annoyance.
Then their eyes met—black and green. Shouta absorbed everything: the freckles, the small lips, the thick eyebrows, and those deep emerald eyes filled with quiet confidence. The omega smiled—a soft, beautiful smile, like he was relieved to see him. Aizawa noticed that just as he was memorizing every detail of the omega, the same was happening in return. They were imprinting on each other.
Izuku’s lips moved, but no sound came out. He barely stopped himself from shouting, “Aizawa-sensei!” His heart leapt into his throat at the sight of a younger Shouta Aizawa. He’d always thought the professor was attractive, always had a bit of a crush on him—but looking into his young eyes was something else entirely. The alpha wore a long-sleeved black V-neck and matching pants, his long hair pulled into a perfect high ponytail, not a strand out of place. His eyes seemed less tired, softer, with shallower shadows. He didn’t just look younger—he looked more alive.
Relief—that was exactly what Izuku felt. A familiar face. Someone he knew he could trust. It was what he needed, because right now, he was lost. Completely lost. And the day had started like any other, in his dorm, attending classes like usual
------
That day had started like any other.
Izuku had gone to class and then headed to the lab where he worked with Hitoshi. They were part of the Applied Research Department in Mechatronic Engineering, working on solutions and inventions to assist rescue and relief teams. As a child, Izuku had dreamed of being a modern hero—someone who saved lives like a firefighter or a police officer who prevented crimes and protected people. But when his secondary gender manifested, he realized that path wouldn’t be possible. So he turned to the one thing he had always excelled at—his mind. He would save lives in another way, by creating better tools for those who did that work.
Now in his second year of university, he and his colleague Hitoshi were helping their professor adjust machinery and conduct research on materials and solutions.
Their lab was a large room with a big window, two desks with computers along one wall, and a crowded center workspace filled with wires and equipment. They were working on two devices that looked more like oversized portable gaming consoles than anything else—black, about twenty centimeters wide, with a display dominating the center and buttons on either side. Identical twins. The goal was to create a device capable of transporting objects—or people—from one point to another.
That day, he and Hitoshi met in the lab as usual. Hitoshi, an alpha with spiky lavender hair and tired, thoughtful eyes, was in a good mood. He carried a large gift bag with a bow—it was clearly a present.
“Good afternoon, Zuku,” he said softly as he entered.
“Hey, Toshi,” Izuku replied, already focused on the equipment. You could almost see the gears turning in his head as he muttered quietly to himself.
“Zuku… Before we start, can I talk to you for a minute?” the lavender-haired alpha asked nervously, placing a gentle hand on Izuku’s shoulder. Izuku snapped out of his trance and looked up.
“What is it? I was having some ideas—I think we can…”
“I’ll hear your ideas in a moment,” Hitoshi said, raising the gift bag into Izuku’s view. “I want to give you this.”
“Thanks...?” Izuku said uncertainly, opening the bag. Inside was a plush, cozy blanket. He lifted it carefully—and that’s when he noticed it smelled just like Hitoshi: the scent of new books and freshly brewed coffee.
“This is…?” His face flushed red as he took a small step back.
“It’s exactly what you’re thinking. A courting gift,” Hitoshi answered like it was no big deal. He gently took Izuku’s hands to stop him from hiding his face. “It’s time I started pursuing you, Zuku. It’s what I want.”
“But… Toshi…” Izuku was almost breathless. His mind couldn’t catch up to what had just happened—he was speechless.
“Zuku, breathe. It’s just a gift. The first one. You don’t have to do anything right now. Just… accept it. See if it fits your nest. All I ask is that you think about it, okay?”
“Okay,” Izuku replied quickly, still unsure of what else to say. He had suspected Hitoshi liked him—especially after Izuku turned down the last alpha who courted him a few weeks back. He stored the gift carefully. He didn’t want to admit it yet, but the blanket was perfect for his nest.
It took a few minutes before he could concentrate again. But when he did, it was like nothing had happened. They got to work. The initial diagnostics were done. Now it was time to run the internal calculations on the devices. Hitoshi had one. Izuku had the other.
It was the last normal thing that happened to Izuku that day.
Moments later, when he regained awareness, he was standing in a classroom holding the device.
___
Confusion.
That was exactly what Izuku felt. Nothing made sense. Hitoshi wasn’t there, and the device in his hand seemed to have powered off. He took a breath and looked around. The classroom he was in looked like their lab—the window, the layout of the walls—but instead of a lab, it was just a small classroom with a few desks and a whiteboard.
The only thing to do was investigate.
He checked his watch: 3:37 p.m., October 17, 202X. But then he noticed—it wasn’t working properly. The time was frozen, and the date… something felt off. He walked out into the hallway. It looked like the university’s corridor. That was familiar. But there was no one around.
From what he could tell, it was the end of the academic day, but he hadn’t encountered anyone. He decided to go back to his dormitory, which was shared only with other omegas. Laws for omega inclusion required universities to not only offer quotas for omega students but also ensure access to safe housing and support. Discrimination in the job market still made it hard for many to study while working.
Despite the quota, classes were still incredibly difficult, and most omegas studied education or healthcare—still shaped by the outdated idea that they were “biologically better at caring.” In any case, Izuku decided to go back to his routine—rest a little, and then call Hitoshi to figure out what had happened.
He reached into his pocket and realized—he didn’t have his phone. He let out a long sigh.
“I put it away to avoid any accidents in the lab… and here I am, after an accident, without it.”
He started walking quickly. He had to contact Hitoshi. He knew the alpha would be worried. But when he arrived at the dorm, he stopped in shock.
The building, which had always had two brick towers, now had only one. Where the other should have been, there was a garden and a large tree where people sat reading and laughing in the shade.
“Where is the tower?”
The omega felt dizzy. Things were only getting worse. Everything felt wrong. He was at his university… and yet he wasn’t. He walked toward the building—maybe he could find some explanation. But when he reached the door, there was a sign posted:
“Reminder: the dormitory will be closed for renovations from November 201X to July 201X.”
Izuku nearly lost his balance. He read the notice again. It wasn’t a typo. The date… was ten years ago.
This had to be a dream. There was no way he was ten years in the past. The machine they were testing wasn’t that powerful. It was meant to teleport people across space—not through time.
He couldn’t breathe. He was hyperventilating —probably having a panic attack. His scent started to leak out. People began turning to look at him. Izuku knew he had to calm down and leave. The looks weren’t just curious or concerned—they were predatory.
He took a deep breath, trying to steady himself and come up with a plan.
If he really was in the past, where could he go for help? He couldn’t go to his own house— it would create a paradox, especially for the younger version of himself. Hitoshi was just a kid now too. Even if Izuku knew the alpha would believe him, it wouldn’t help.
He had to find someone he could trust. Someone who would believe his story. Someone who wouldn’t cause a temporal paradox. Someone who was already an adult.
The question was—who?
In the middle of his spiraling thoughts, with anxiety rising…
Someone approached him.
And that’s how Shouta and Izuku met —once again. Their eyes locked, and the world stopped.