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Izuku didn’t notice the pattern at first.
That was the thing about patterns, they felt obvious only once you stepped back far enough to see them. Until then, they were just moments. Coincidences.
Small, unremarkable choices that didn’t mean anything on their own.
Like the way Sero always ended up beside him during cooldown stretches.
They’d collapse onto the gym floor after training, muscles burning, lungs aching, and somehow Sero would be there, stretching long limbs with lazy ease, offering commentary that was half-joke, half-genuine advice.
“You’re tensing your shoulders again,”
Sero said one afternoon, looping his tape back into place. “You do that when you overthink.”
Izuku flushed. “I- I’m not overthinking!”
Sero hummed, unconvinced. “Sure, man.”
He didn’t push it. Just leaned back on his hands and let the silence settle comfortably between them.
Izuku realised, distantly, that he wasn’t rushing to fill it.
During combat drills, Sero’s tape found Izuku instinctively.
Not restraining him, never that, but guiding. Redirecting. Catching him mid-fall when Blackwhip stuttered instead of surged.
“Gotcha,” Sero said easily, hauling him upright after one particularly messy landing.
“Sorry! I misjudged my angle-”
“You didn’t,” Sero interrupted. “You adjusted fast. That was good.”
Izuku blinked.
Praise usually came with caveats.
Corrections. Notes for improvement.
Sero’s didn’t.
It wasn’t just training.
In the cafeteria, Sero would slide his tray closer without comment if the room got too loud. During movie nights, he’d casually take the seat beside Izuku, feet hooked over the edge of the couch, offering popcorn without making it a thing.
Once, during a particularly rough week, Izuku realised he’d started saving a seat for Sero without thinking about it.
The realisation startled him enough that he nearly dropped his notebook.
That’s… normal, he told himself.
Friends do that. Right?
“Hey, Midoriya.”
Izuku looked up from his notes to find Sero leaning over his desk, chin resting on his hands.
“Yes?”
“You’ve been staring at that page for like five minutes.”
“Oh! I was just-uh-recalculating support ratios for-”
Sero tapped the notebook lightly with two fingers. “You’re spiralling.”
Izuku froze.
Sero softened immediately. “Hey. I don’t mean that in a bad way.”
He pulled a chair closer and sat, lowering his voice without needing to be asked. “You’re allowed to stop thinking sometimes, you know.”
Izuku laughed weakly. “I don’t really know how.”
Sero grinned. “Lucky for you, I’m great at distractions.”
And then he launched into a ridiculous story about Kaminari attempting to tape himself to the ceiling “for science,” and Izuku found himself laughing, really laughing, before he could stop himself.
The knot in his chest loosened.
Other people noticed before Izuku did.
“You and Sero been hanging out a lot,”
Mina said one evening, eyebrows dancing as she passed them in the hall.
Izuku nearly tripped. “W-we’re just friends!”
Sero slung an arm around his shoulders briefly, light, familiar, gone as quickly as it came. “Relax, Midoriya. Friends are allowed to exist.”
Mina’s grin widened. “Sure they are.”
Izuku didn’t understand why his face felt so warm afterward.
Late at night, when the dorms grew quiet and the world felt smaller, Izuku sometimes found himself sitting on the common room floor with Sero, backs against the couch, talking about nothing in particular.
Music played softly from Sero’s phone.
Izuku talked more during those nights than he usually did, about training frustrations, about the pressure of expectations, about how exhausting it was to always feel like he had to earn the space he took up.
Sero listened.
Didn’t interrupt. Didn’t minimise.
Just listened.
“You don’t have to prove anything to me,” Sero said once, quietly, staring at the ceiling.
Izuku swallowed. “I know.”
But the truth was… it felt different hearing it anyway.
By the time winter crept in, by the time decorations started appearing in the halls and tinsel was strung carelessly over doorways, Izuku felt something settle into place.
Not excitement. Not nerves. Comfort.
And somewhere along the way, without him realising it, Sero had become the person Izuku looked for first when he entered a room.
He just hadn’t asked himself why yet.
Izuku started noticing it when Sero wasn’t there.
Training ran late one evening, the winter air biting through the open doors of Gym Gamma. Izuku wiped sweat from his brow and instinctively glanced to his left-
Empty space.
Sero was sparring on the far side of the room with Kirishima, tape snapping and retracting in sharp arcs. Laughing.
Loud. Effortless.
Izuku felt something… tug.
Not jealousy. He didn’t think. Just a faint, unfamiliar pull that made his attention drift no matter how hard he tried to focus on his own form.
That’s new, he thought, frowning at himself.
He began waiting.
Not obviously. Not in a way anyone else would clock.
But he’d linger a moment longer in the hallway after class. Slow his packing just enough to see if Sero would appear. Choose the long route back to the dorms because Sero liked it better, said the cold felt “less aggressive” there.
“You don’t have to walk me back, you know,” Sero said once, smiling sideways.
“I- I know,” Izuku replied quickly. Too quickly. “I just… don’t mind.”
Sero’s smile softened. “Yeah. Me neither.”
The first real choice came during patrol practice.
Teams were being assigned, voices overlapping as names were called.
Izuku’s heart stuttered when Aizawa paused.
“Midoriya. Sero.”
Izuku exhaled before he realised he’d been holding his breath.
The patrol was quiet, snow crunching underfoot, streetlights reflecting softly off frozen pavement. Sero walked close enough that their shoulders brushed when the sidewalk narrowed.
“You’re tense,” Sero noted gently.
“Sorry.”
“Don’t be.” Sero slowed his pace just enough to match Izuku’s.
Izuku nodded, throat tight.
It was during a late-night study session that things shifted further.
Izuku had spread notebooks across the common room table, muttering calculations under his breath. Sero dropped into the chair across from him, spinning it backwards and resting his arms along the back.
“You’ve been at this for hours.”
“I’m almost done.”
“You said that an hour ago.”
Izuku winced. “I just need to-”
Sero reached out and gently closed the notebook.
Not forcefully. Not teasingly.
Just… decisively.
Izuku looked up, startled.
“Hey,” Sero said quietly. “You’re burning yourself out.”
Izuku opened his mouth to argue, then stopped.
Because Sero wasn’t annoyed. Wasn’t judging. He was just… concerned.
“Oh,” Izuku said, small.
Sero smiled. “Come on. Five-minute break. I’ll even let you pick the music.”
Izuku laughed despite himself. “You say that like it’s a sacrifice.”
“It is,” Sero replied solemnly. “Your playlists are emotionally devastating.”
By the time December settled fully over U.A., Izuku’s thoughts had changed shape.
He caught himself thinking:
Sero would like this.
I should tell Sero.
I wonder if Sero’s free.
Once, Kaminari flopped onto the couch beside him and squinted. “Dude. You smile when Sero texts you.”
Izuku nearly dropped his phone.
“I do not.”
Kaminari hummed. “Sure. And I don’t scream when I see a pretty girl.”
Izuku hid his face behind his scarf, heart racing.
The decorations went up a few days later. Garlands. Lights. Paper snowflakes taped slightly crooked to the walls.
And mistletoe.
Izuku noticed it in passing at first, over a doorway near the common room, tied with a neat red ribbon. He paused beneath it instinctively, then moved on just as quickly, cheeks warming.
It’s just tradition, he told himself.
Still… every time he passed that doorway afterward, he found himself glancing up.
Wondering.
One evening, Sero stopped beside him there.
“Hey, Midoriya.”
Izuku turned. “Yeah?”
Sero followed his gaze upward.
“Oh.”
They both froze.
Laughter and voices spilled out from the common room behind them, the warm glow of lights framing the doorway. The mistletoe hung innocently overhead, swaying slightly as someone brushed past inside.
Neither of them moved.
Neither of them stepped away.
Izuku’s heart thudded.
Sero scratched the back of his neck, a rare hint of nerves slipping through his easy confidence.
“…So,” he said lightly. “Guess this is a thing now.”
Izuku swallowed.
“Yeah,” he said. “I guess it is.”
And for the first time, he didn’t rush to escape the moment.
Izuku nodded, fingers curling lightly into the hem of his hoodie. The sound of laughter behind them felt distant, muffled, like it belonged to another room entirely.
They stood there, neither rushing, neither pretending it was a joke. The mistletoe swayed gently above them, catching the light. Izuku became acutely aware of how close Sero was, close enough that he could feel warmth radiating off him, close enough that stepping away would feel deliberate.
Sero glanced at him, really looked at him.
Not teasing. Not playful.
Just… present.
“We don’t have to make this weird,”
Sero said quietly.
Izuku huffed a small, nervous laugh. “I don’t think we are.”
That earned him a smile, not Sero’s usual grin, but something smaller.
Something careful.
“Good,” Sero murmured.
He shifted closer, slow enough that Izuku had time to think, to second-guess, to overanalyse the way he always did.
He didn’t.
Izuku tilted his head up without even realising he was doing it.
The kiss was brief. Soft. Barely there. But it landed like a truth.
Sero’s hand hovered at Izuku’s elbow, never quite gripping, just grounding him there. Izuku’s heart raced, but there was no panic this time, no spiralling thoughts, no internal alarms. Just the quiet understanding that this felt… right.
When they pulled back, neither of them spoke immediately.
Izuku exhaled first, breath shaky but
warm. “Oh.”
Sero laughed under his breath. “Yeah. Oh”
They stayed close for another second, not touching, not separating either, before Sero finally stepped back just enough to give Izuku space.
“We should probably head back in,” he said, glancing toward the common room. “Before someone comes looking.”
Izuku nodded, cheeks warm.
“Probably.”
They turned together.
They made it exactly two steps.
“WAIT.”
Kaminari’s voice cut through the room like a siren.
Izuku froze.
Mina popped up beside him instantly, eyes wide, scanning between the two of them. “No way.”
Jirou followed, arms crossed, smirk already forming. Kirishima leaned in from behind her, curious.
Sero lifted his hands defensively.
“What?”
Mina gasped dramatically. “You were gone for, like, a minute.”
Jirou glanced pointedly at the mistletoe.
“Uh-huh.”
Izuku felt his face burn, but before he could spiral, Sero just laughed, easy, unbothered.
“It’s Christmas,” he said with a shrug.
“Stuff happens.”
Kirishima grinned. “Manly.”
Izuku glanced sideways at Sero, half-expecting regret.
Instead, Sero leaned closer and murmured, just for him, “You good?”
Izuku smiled, small, but real.
“Yeah,” he said. “I am.”
And as they stepped fully back into the warmth and noise of the common room,
Izuku realised something quietly important. For once, he wasn’t overthinking what came next.
He was just… here.
The party wound down slowly.
By the time the music softened and people started peeling off toward their rooms, the common room lights were dimmed to a warm glow. Someone had abandoned a mug of cocoa on the table. Tinsel sagged where it had been tugged too many times.
Izuku lingered longer than usual, helping Mina collect stray decorations, nodding along to Kaminari’s rambling story without really hearing it. His thoughts kept drifting, not spiralling, just… returning.
To the doorway. To the mistletoe. To the way Sero had looked at him afterward, like nothing had changed and
everything had.
When Izuku finally excused himself and headed down the corridor, the dorm was quiet in that end-of-night way, footsteps muffled, laughter distant behind closed doors.
“Hey.”
He stopped.
Sero leaned against the wall near the stairwell, arms folded loosely, hair still a little mussed from the party. He looked relaxed, but not casual, like he’d been waiting without meaning to make it obvious.
Izuku’s chest did that familiar, fluttery thing again.
“Oh,” he said. “Hey.”
They stood there for a second, the silence easy this time.
“Just wanted to check in,” Sero said.
“Make sure you didn’t, y’know… disappear into your brain.”
Izuku smiled faintly. “I thought about it.”
“Figures.”
“But I didn’t,” Izuku added. “I’m… okay.”
That seemed to matter.
Sero’s shoulders loosened, just a touch.
“Good.”
They started walking together without discussing it, steps naturally falling into sync as they headed toward the stairs.
No hands brushing. No rush to close the space. Just proximity.
At the landing, Sero stopped again.
“So,” he said, eyes forward. “About earlier.”
Izuku’s fingers curled reflexively, but his voice stayed steady. “Yeah?”
“We don’t have to label it,” Sero said.
“Or explain it. Or make it a thing unless you want it to be.”
Izuku considered that, not as a defence, but as an option.
“I don’t feel like running from it,” he said honestly.
Sero turned, surprised, then smiled.
“Yeah,” he said. “Me neither.”
There wasn’t another kiss.
Instead, Sero reached out and gently nudged Izuku’s shoulder with his own, a quiet, familiar gesture.
“Goodnight, Midoriya.”
Izuku hesitated, then returned the motion, just as lightly.
“Goodnight, Sero.”
They parted there, footsteps heading in opposite directions.