Chapter Text
The U.A. dorms buzzed with their usual nighttime chaos. The air smelled faintly of butter and sugar thanks to Sato’s latest baking spree, while Kaminari and Mina argued over a video game in the common area, the flashing lights from the TV casting bursts of color on the walls. Kirishima lounged upside down on the couch, offering unhelpful commentary about who was “totally crushing it, bro,” while Jiro flicked one of her headphone jacks at his forehead without even looking up from her phone.
To anyone else, Class 1-A seemed like a group of carefree teenagers unwinding after a long day of intense hero training. Their laughter rang through the halls, echoing all the way upstairs. If you squinted, you might think this was just a normal dorm, filled with kids whose biggest worries were homework and late-night snacks.
But behind one particular closed door, Tenya Iida sat alone.
His room, neat to the point of sterility, smelled faintly of cleaning spray and the laundry detergent he used religiously. The desk was spotless, each book stacked by size, his hero costume maintenance kit lined up in perfect order. The stillness was suffocating, made worse by the faint laughter downstairs. His glasses sat on his desk; without them, his vision blurred, leaving him staring at his trembling hands like they belonged to someone else.
The light from his desk lamp illuminated his knuckles. The faint scars and fading bruises weren’t from training. He flexed his fingers, guilt flooding him as the sharp sting from earlier pressed into his consciousness. He’d been careful, always careful, but tonight he’d slipped.
His quirk, Engine, was a symbol of speed, of precision, of power. To his classmates, Iida was the responsible one—the leader, the one who enforced rules and structure when no one else could. He was their big brother, their compass. They didn’t know that when the dorm lights went out, and the responsibility became too heavy to bear, he would retreat to his perfectly organized sanctuary, curl in on himself, and try to quiet his thoughts in ways he’d never be proud of.
A soft knock jolted him upright.
“Yo, Iida, you up?” Sero’s voice, warm and teasing, floated through the door.
Tenya froze. “I—I am, yes,” he called back, his tone clipped. “Do you require something, Sero?”
Sero chuckled. “Just checking if you wanted a brownie before Kaminari eats the rest. That guy’s like a sugar vacuum.”
“I—ah, no. Thank you.”
There was a pause. “You sure, dude? You sound… I dunno, stressed or something.”
Tenya’s throat tightened. He forced his tone into one of brisk dismissal. “I appreciate your concern, but I am simply… studying.”
Sero hummed softly. “Alright, if you say so. Just… don’t overdo it, man. You’re always running at, like, a hundred miles per hour. Even engines overheat, y’know?”
Tenya’s heart stuttered at the unintended accuracy of that statement. He waited until Sero’s footsteps receded down the hall before letting out the breath he’d been holding.
Downstairs, Sero dropped himself into a beanbag with a frown. He’d known Iida long enough to recognize when the guy’s “everything’s fine” voice was masking something. Normally, Iida’s room was open to anyone who needed a quiet space to study or vent, and Sero had walked in plenty of times to find him polishing his armor with methodical precision. But tonight’s clipped responses? The tension in his voice? That wasn’t normal.
“Yo, Sero, you bringing snacks or what?” Kaminari called, mouth already full of a brownie he’d swiped.
Sero tossed him a glare. “You’re lucky I didn’t trip you on the way back.”
“Harsh, dude.” Kaminari grinned, crumbs sticking to his cheek.
Kirishima nudged Sero with his foot. “What’s with the face, man? You look like Todoroki when he’s trying to do math.”
“Nothing.” Sero leaned back, staring at the ceiling. “Just… Iida’s acting weird.”
“Isn’t that just Iida?” Mina chimed in from the floor, laughing. “The guy’s practically allergic to relaxing.”
Sero shook his head. “Nah, this feels different. Like… stressed-out different.”
Jiro finally looked up from her phone, raising an eyebrow. “Maybe he’s just tired. We’ve all been pushing hard in training.”
“Maybe,” Sero muttered, but he couldn’t shake the image of Iida’s tense voice, or the way he hadn’t even opened the door.
Upstairs, Iida slipped his gloves back on. The snug material covered his hands, concealing the faint red lines he couldn’t stop tracing with his eyes. He knew what he was doing was wrong. He knew that if anyone—especially his classmates—found out, they would worry, they would look at him differently, and he couldn’t let that happen.
He had to be perfect.
Iida leaned forward, burying his face in his hands, the weight of leadership pressing down on him. His brother, his classmates, his teachers—they all expected so much from him. And he delivered. Always. Because if he didn’t… who would he be?
His mind replayed every mistake, every moment he’d faltered in battle, every time he hadn’t been fast enough or strong enough to protect someone. The images blurred together until he felt dizzy. He reached instinctively for his drawer, the one with the first-aid supplies he always kept stocked.
The next morning was bright and cheerful in contrast to the heaviness that had settled in Iida’s chest. The dorm kitchen was alive with noise. Mina and Kaminari were attempting pancakes, which looked more like abstract art, while Yaoyorozu offered polite advice they both ignored. Shoji passed plates down the line like a silent assembly worker, and Jiro scrolled through her phone, pretending not to be amused.
“Morning, Iida!” Kirishima called cheerfully as Tenya descended the stairs, perfectly pressed uniform making him look like he was ready for an inspection.
“Good morning,” Iida replied with a polite bow.
Sero noticed immediately that Iida’s smile didn’t reach his eyes. He watched as Iida adjusted his gloves twice, a subtle movement that most wouldn’t notice.
“You alright, dude?” Sero asked, leaning casually against the counter.
“Of course,” Iida said, voice brisk. “Thank you for your concern, but I am perfectly well.”
Sero narrowed his eyes. “You sure? You seem kinda… off.”
Iida stiffened. “I assure you, I am fine.”
The conversation was cut short by Bakugo storming into the kitchen, yelling about “idiots who can’t cook” and stealing a plate from Kaminari, who yelped in protest. The room dissolved into chaos, but Sero’s eyes stayed on Iida, who moved like a shadow, quiet and careful, slipping into his usual role of making sure no one set the dorm on fire.
Sero didn’t buy it.
Classes that day passed in a blur for Iida. He threw himself into combat training, his movements sharp and precise, determined not to show any weakness. To his classmates, he was the same as always: disciplined, focused, the model student.
But Sero kept watching.
He noticed the way Iida winced when Kaminari playfully slapped his shoulder, how he flinched slightly when Tokoyami brushed past him during drills. He noticed how Iida kept his gloves on even after training, long after everyone else had shed their gear.
Sero wasn’t stupid. Something was wrong.
That night, the dorms settled into their usual rhythm. Music drifted softly from Jiro’s room, Mina and Kaminari were plotting a prank, and Todoroki sat quietly in the common area with a cup of tea.
Sero made his way upstairs, heart pounding. He stopped outside Iida’s door, hesitating before knocking softly.
“Iida? It’s me.”
There was a pause. Then, “Yes, Sero. What do you need?”
“Can I come in?”
Another pause. Then a reluctant, “Very well.”
The door opened to reveal Iida’s immaculate room. Sero stepped inside, eyes scanning the tidy space. Iida stood stiffly by his desk, glasses catching the light.
“You okay, dude? You’ve been… off lately.”
“I am fine,” Iida said quickly. Too quickly.
Sero crossed his arms. “You know I’m not buying that, right?”
Iida flinched. “Sero, I—”
Sero’s gaze drifted to the edge of the desk. A small roll of gauze peeked out from a drawer that hadn’t been fully closed. His stomach dropped.
“Iida… what’s going on?”
Iida’s composure cracked, just for a moment. His shoulders slumped, and he looked away, unable to meet Sero’s gaze.
“I… I cannot burden you with this,” he whispered.
“Try me,” Sero said softly, stepping closer.
For a long moment, the room was silent except for the faint chatter of their classmates downstairs. Then Iida’s voice broke.
“I… I don’t know how to stop.”
And that was how it began.
That was how Hanta Sero became Tenya Iida’s quiet protector, the one who stayed up late just to make sure Iida wasn’t alone, who made jokes to mask his worry, who became a shield no one else realized Iida needed.
Their classmates thought it was cute, the way Sero always lingered near Iida, always checked in on him. They thought it was friendship, maybe even a crush. They didn’t see the trembling hands Sero held steady, or the nights he sat with Iida in silence, refusing to leave until the tears stopped.
Because Iida was their leader, their role model, their steady engine. And no one could know that even engines break down.