Archive of Our Own

Your Systems Architecture lab started in nine minutes. Room 4.12, Kepler Building, second floor. The sign above your head read MECHANICAL ENGINEERING CAPSTONE LAB in blocky red letters, which was wrong by every metric that mattered.

The campus map had done this to you. The PDF version on the university website, copyright 2014, listed Kepler as "adjacent to Huxley." In practice, adjacent meant a twelve-minute walk across a courtyard, through a car park, past a coffee stand you'd never once seen before. You were in Huxley, third floor. But, wrong building, department, discipline. Basically, wrong everything. This is so not your place.

Your laptop bag strap had been losing its will to live since October; it slid off your shoulder for the fourth time while you stood in the doorway of a room that smelt like solder and burnt ambition. You pulled out your phone. The blue dot on the campus map placed you inside Kepler. The blue dot was a liar.

The workshop stretched out in front of you. Workbenches in rows under flat fluorescent lighting, cluttered with soldering stations, power tools, half-assembled chassis trailing wires. Metal shavings dusted the floor like industrial confetti. Nothing in here looked like a terminal. Nothing in here belonged to your degree.

"You lost?"

Barnes. Third row from the back in your Thursday AI module, usually quiet until a lecturer got something technically wrong, at which point he corrected them with the patient precision of someone who'd been waiting for the mistake since the sentence began. He wore a grey henley today, sleeves shoved past his elbows, leaning against his workbench with his arms crossed while he watched you with something between curiosity and amusement.

You'd noticed Bucky before. The way you noticed anyone whose seminar contributions made you sit straighter. Academically, exclusively that.

"Looking for 4.12."

"Wrong building entirely." He tilted his head towards the window. "This is Huxley. Kepler's east, past the courtyard, by the bike racks."

"The campus map says this is Kepler."

"The campus map hasn't been accurate since before we enrolled." The corner of his mouth pulled up, barely, like he found your faith in university infrastructure endearing. "You're in the Thursday module, yeah? Machine learning applications."

"That one. Tuesday seminar too."

"Right." Something behind his eyes shifted. A recognition, quiet, unhurried. "You did the finite state machine presentation a few weeks back."

"Three weeks ago."

"It was good." He didn't elaborate. His eyes stayed on yours when he said it, though, holding longer than the compliment required, warm in a way you felt at the base of your throat.

You should have said thank you, turned around, found Kepler the honest way. Your lab was down to seven minutes. Your lecturer had a door-locking policy that you'd assumed was a bluff right up until someone tried the handle at 10:02 last Thursday. You weren't looking at his forearms, totally not. The pushed-up sleeves, the lean muscle shifting when he adjusted his weight, the micro-scarring across his knuckles from metalwork. None of it was relevant to your navigational crisis. You were lost, and really fucking late.

"So what is all this?" you heard yourself ask, because apparently you were also staying.

"Capstone projects." He gestured around the room. "Final year builds."

From the far end of the workshop, a soldering iron hissed in short precise bursts. Stark was hunched over his workbench with his back to the room, entirely absorbed.

He hadn't looked up when you walked in. He hadn't registered your conversation. His t-shirt pulled across his shoulders when he reached for a component, the tension in his upper back visible through the fabric, the focused set of his frame radiating the specific energy of someone who'd forgotten other people existed. You clocked all of this in about two seconds before deliberately looking away.

Bucky's workbench held a prosthetic arm in a custom cradle, matte black with silver joint plates, articulated from shoulder to fingertip. The fingers curled in sequence while you watched, slow, deliberate, each one bending with a mechanical precision that made something in your brain light up despite itself.

"That yours?"

"Since second year." He uncrossed his arms. His gaze dropped to your laptop bag for half a second before returning to your face. When he spoke again, his voice was different. Still quiet, but the idle friendliness was gone. This was directed. "The hardware's finished. Servos, flex sensors, full range of articulation. Every mechanical component works." He paused, deliberate. "But it needs a software layer. Gesture mapping, real-time haptic feedback on screen, a responsive front-end system that talks to the hardware without latency. I need someone who writes that kind of logic."

He stepped closer. Not crowding, just halving the distance until the warmth coming off him registered against your skin, until the workshop felt considerably smaller than its dimensions. His eyes settled on yours, held there without wavering.

"I've been looking for the right person."

The sentence had a professional shape. The way he said it did not.

"You're describing a full-stack integration." You shifted your laptop bag higher, mostly to give your hands a job. "That's not a small ask."

"I know exactly what I'm asking." His gaze was steady, certain, the kind of eye contact that made it very difficult to remember you had a lab to be at. "Your systems architecture is clean. Your seminar code is clean. I've been paying attention."

For three weeks, probably longer, probably since September.

Your mouth opened to respond.

Tony's soldering iron clicked off.

"Oh, we're doing this now?" His voice carried across the workshop before he did. He straightened, pulled his safety goggles up into his hair, turned around.

For the first time since you'd walked in, his full attention landed on you. Dark eyes tracked from your face to your laptop bag to your face again with the unhurried focus of someone running an assessment. His expression recalibrated mid-look, something shifting behind it, sharpening.

He crossed the room in a few strides. Up close, Tony was every bit the problem Bucky was, just louder about it. He stopped on your other side, mirrored Bucky's position like a territorial claim.

You were now flanked by two engineers who had arranged themselves like competing recruitment booths at a careers fair you hadn't signed up for.

"If we're recruiting," he said, still looking at you, "I should mention my project is slightly more ambitious than a single limb."

"Your project fell over last Tuesday." Bucky's voice was level. "In front of the whole lab."

"Centre-of-gravity calibration test."

"It wasn't."

Tony didn't acknowledge this. His eyes were on yours, direct, unbroken. The eye contact was nothing like Bucky's. Bucky's was warm, grounding, something you could settle into. Tony's sat behind your ribs. Every time you met it, you felt the heat of it somewhere inconvenient.

"Full humanoid," he said. "Systems AI. Sensor integration, decision architecture, neural net training. The hardware moves. It just can't think yet." His voice dropped half a register. "I need someone who can build it a brain."

"That's a neural net."

"That's you." He said it like a conclusion he'd already proven. "I've heard you talk about recursive systems in lecture like it's a first language. Most people in that room fake their comprehension. You don't."

"What's your repo look like?" you asked.

Tony blinked. "Functional."

"His commit messages say 'fixed stuff,'" Bucky offered quietly, something helpful, or lethal.

"One time."

"Three. I checked."

"You checked my repo?"

"Know your competition."

Your laptop bag slid again. Both of them tracked it. Not the bag itself; what it carried. The laptop, the code, the architecture, the brain they were both trying to get their hands on. You hitched the strap back up. Both pairs of eyes followed the movement of your hand.

"What middleware is the arm running?" you asked Bucky.

"ROS." He shifted closer. Close enough that you could count the flecks of grey in his eyes, close enough that professional was a generous word for the distance between you. "Motor command layer's handled. The interface layer is empty. Nobody in the mech cohort writes front-end logic clean enough to integrate without breaking the pipeline."

"So you need someone who can build a responsive UI that maps gestural input to real-time visual output without introducing latency."

His jaw tightened. His eyes dropped to your mouth for half a second before catching themselves, pulling back up to meet yours with an expression that looked like you'd just said something devastating in a language only he understood. Your breath caught. Just once, and he noticed.

Tony, who had been involuntarily side-lined during this exchange, physically could not stand it.

"My decision architecture." He stepped into your sightline, reclaiming it. "You were about to ask."

"Was I?"

"Neural net. Supervised learning for motor function, reinforcement for adaptive behaviour." His eyes locked onto yours, close enough now that you could smell solder on his skin, something metallic underneath. "I could build it myself."

"Then why do you need me?"

The workshop went very quiet. Bucky didn't smile, although the restraint was visible through his whole body. Tony's face changed. The performance fell away for two clean seconds, replaced by something unguarded, almost startled. "Because you'd build it better than me." No charm. No projection. Just the flat truth delivered like it cost him something. "Your systems design is sharper than mine. I've sat through enough of your work to know."

The honesty lasted long enough to matter. Then the mask slid back.

"Plus, my project is getting published. You'd want your name on that."

"His project can't stand up," Bucky said.

"It stood for forty-five seconds."

"Then it fell. On its face."

You bit the inside of your cheek. Something in your expression cracked; both of them clocked it instantly, straightening like your almost-smile was a metric they fully intended to win.

Two pitches. Both real, both the kind of portfolio line that would make a recruiter pause mid-scan. A prosthetic interface with genuine hardware integration. A humanoid AI system with publishable scope. Either project would be the strongest thing on your CV before you'd even graduated. The fact that both offers came attached to people who made your pulse stutter was a variable you were electing not to examine within their line of sight.

"Send me your project briefs." You adjusted your bag with a finality that signalled exit. "I'll review them this week."

"Inbox tonight." Tony already had his phone out. "Full scope, timeline, technical spec."

"Mine's already done." Bucky reached behind him on the workbench. He produced a physical folder, printed, tabbed, colour-coded.

Tony stared at it. "You had that ready."

"I respect people's time."

"You had a printed recruitment pack for a comp sci student who might wander in?"

"For the right one." Bucky held it out. His fingers grazed yours when you took it, slow, deliberate, warm. The contact lasted a beat longer than transfer of a document required.

Tony's jaw flexed.

"I'll read both." The folder sat against your chest. You held each of their gazes in turn, long enough to give nothing away. "Properly."

"You'll like mine better," Tony said.

"You'll like mine more," Bucky said.

You left that unanswered, because you genuinely didn't know which one you agreed with, and that felt like the most honest thing in the room.

Your phone buzzed before you reached Kepler.

He'd already added you to the repo. You had never given him your GitHub. You photographed the folder, and screenshotted the email. Your group chat needed this immediately.

In the Huxley workshop, Tony refreshed his sent folder. Bucky reorganised tools that didn't need reorganising. Neither looked at the other. Both checked the door more than once.