Chapter Text
The elevator groaned to a halt with a hydraulic hiss, doors parting to reveal a narrow corridor of reinforced steel and humming fluorescent lights. Kara stepped out behind Lena, her boots clicking softly against the polished floor. The air was cool. Sterile. It smelled faintly like a hospital.
Ahead, a massive vault door dominated the hallway. A blackened lead-lined metal framed in dense alloys, tall enough to dwarf a semi-truck, thick enough to stop a small war.
Kara blinked. "That's… a lot of door."
Lena didn't slow her pace. "It's overkill until it's not."
She reached a control panel mounted beside the vault. A faint beep echoed as she pressed her palm to a scanner. A light passed over her hand, followed by a second device scanning her face, then her eye. Then she leaned in:
"Lena Kieran Luthor. Level Zero clearance."
Another beep. A panel slid open, revealing an old-fashioned mechanical keypad. Lena entered a pass-code so long that Kara lost track halfway through.
"Is all this really necessary?" Kara asked, watching the process. "It's not… not guarded by killer robot or anything?"
"Well, the robot doesn't kill," Lena smirked faintly. Kara assumed she was telling a joke. Lena's smirk faded as she entered the final buttons on the panel "…Not anymore, at least."
With a final hiss of pressure release, the enormous door shuddered, then slowly began to open inward with a deep metallic groan. Lena stepped inside. Kara hesitated for half a second before following.
The space inside was huge. A cavern of reinforced walls and softly glowing containment cases, stacked in long rows that stretched far beyond what Kara expected. Some shelves went as high as the ceiling. Others looked like sealed lockers. Everything was quiet except for the low electric hum.
Rows of objects gleamed under the white lighting, some metallic and obviously technological, others more obscure. Alien geometries twisted into impossible shapes. Jewellery that shimmered without light. Books sealed in airtight containers. A few things looked like toys. Others resembled weapons. Many looked like junk. But Kara knew better than to assume.
She stepped closer to one of the containment cases and tilted her head. Inside floated a small orb, faintly glowing purple, spinning endlessly in a slow orbit.
Kara pointed. "What's this one do?"
"We don't know," Lena said simply. "Lex recovered it from an asteroid mining project ten years ago. No one's figured out how to open it. It might be dangerous. Or just broken."
Kara blinked. "You really don't touch anything, huh?"
"Lex didn't," Lena said, her voice clipped. "And believe me, he liked touching things. If he was afraid of what something might do, that meant it was really dangerous."
They passed another section. Kara saw what looked like an alien sculpture of twisting silver tendrils, encased behind energy shielding. The next shelf over held something that looked suspiciously like a crystal lollipop in a block of ice.
Lena continued, her tone all business. "Anything potentially radioactive is stored at the far end, under additional containment. Still, don't assume anything in here is safe. Half of it came through black market channels. No labels, no provenance, no real testing. And our last vault tech ended up-" she paused, then softened it, "-well, he doesn't work here anymore."
Kara gave a nervous half-laugh. "Okay. Don't touch glowing stuff. Got it."
They walked in silence for a moment longer before Lena paused her step, remembering something important to her. She spoke again without turning. "And in case you're wondering, there's no Kryptonite in this vault."
Kara's brow lifted. "Really?"
Lena nodded. "Lex kept that elsewhere. Off the books. I personally cleared this entire wing after he disappeared. Anything even remotely green or crystalline was removed and neutralised."
"Huh…" Kara mused wistfully.
"You sound disappointed?" Lena questioned, turning to look at her. "You do know what that stuff does to you?"
Kara relaxed a little, then chuckled, "Kal-El told me about Kryptonite when I arrived. Little pieces of Krypton, irradiated by space and yellow sun. Said it was one of few things that could hurt us."
"It does more than hurt you," Lena added, still curious about Kara's reaction.
"I know," Kara shrugged. "Well, no. I don't know. I've never seen it. Never even felt it. But it's little sad, no? Little pieces of Krypton made it all the way out here. And now it's all gone. Like home."
"Gone?" Lena gave a dry laugh. "Maybe in Metropolis. But Lex had caches all over. And he wasn't the only madman to realise its effect on Superman. I'm sure there are safehouses, labs and buried facilities in countries around the world that have samples of the stuff. It's not all gone. I doubt it ever will be."
Kara swallowed. That was… unsettling.
"Still," Lena added, stopping in front of a sealed column of dark material wrapped in chains of containment glyphs. "You're safe here. I've made sure of that."
Kara looked at her, thoughtful. "Thank you. So, where we start?"
Lena extended her arms in a wide gesture toward the rows of containment cases, the faint blue glow of the security fields reflecting off her sleeves.
"Start wherever you want," She said. "There's no real system yet. Everything that's still down here is equally untested, undocumented, or frankly, unwelcome. Go with your gut."
Kara hesitated, scanning the rows. So many artefacts, shapes and materials she couldn't name, some faintly familiar, most completely alien. Some were clearly technological, metal panels, humming nodes, tools with moving parts or blinking indicators. Others were inert, stone tablets, metal rods, crystalline objects, or even things that looked handmade.
She drifted toward the nearest shelf, eyes narrowing as she studied a black oval the size of a coconut, encased in a thick, clear shell. Inside, a violet mist swirled like a storm trapped in a bottle. It reminded her of the storms that used to roll over the northern poles of Krypton.
She passed on it, it looked dangerious and Kara was more interested in things that would turn out to be useful.
Skipping anything with too many sharp edges or that pulsed in ominous reds. Her eyes flicked past a box made of braided organic fibres, a glittering stone pyramid, a floating cube spinning endlessly on three axes.
Kara moved on. She passed a case holding what looked like a charred book, its pages fused shut. She didn't touch it. A floating mask behind glass stared at her. She didn't like the way the eyes glowed. Then her gaze landed on a golden necklace. It pulsed gently like a heartbeat.
"Magic," She muttered, backing away.
Lena, a few steps behind, gave her a dry look. "You know, not everything that glows is magic."
"No, but that one feel like it," Kara replied quickly, shuddering faintly. "Seen it on Themyscira. Magic is unpredictable. No rules, no logic. I don't like it." She blushed slightly, hoping that Diana would never hear her say that in person.
"You know the saying," Lena offered as they passed another display, a tangled vine frozen in amber. "Any sufficiently advanced technology is indistinguishable from magic."
Kara raised a brow. "I not know. But makes sense."
One device caught her eye. A small, gun-shaped instrument made of brushed silver and blue alloy. Sleek, elegant, unmistakably not of earth origin.
Kara picked it up casually. "Huh… What is this?-"
"Don't touch that!" Lena turned sharply. Her heels echoed as she strode toward Kara.
Kara froze, blinking at the woman.
"Put it down carefully," Lena reached her just as Kara tilted the device in her hand. "That thing… Of all the things. I had no idea that was still in here."
"This?" Kara's eyes widened, more in disbelief than fear. She held it up closer to her face, inspecting the gun for any obvious dangers.
"I'm serious," Lena hissed. "I thought we got rid of all of Lex's anti-Kryptonian weapons. I'm so sorry Kara, I had no idea. Lex used it during one of his attempts on Superman's life. And it nearly worked."
"This is no weapon," Kara giggled. She ran her fingers along the side of the gun, highlighting Kryptonian glyphs that were faded into the side of it. "Solar Pattern Adjustor – Series 3." She translated with a sly grin. "It's tanning gun."
Before Lena could stop her, Kara flicked the switch with a quiet click.
A low hum filled the air, followed by a gentle burst of warm, reddish light that bathed her forearm. The sensation was faintly nostalgic, summer on Argo. She let it run for a few seconds, then switched it off and turned her arm toward Lena.
"See?" Kara said proudly, flexing her now slightly golden-toned skin. "Had one just like this back home. Would tan before formal events." She smiled fondly at the memory. "Make you look healthy, yes?"
Lena's face was stuck somewhere between relief and exasperation. "You're telling me my brother tried to assassinate Superman with a Kryptonian tanning lamp?"
Kara giggled, then her smile faltered a little as she flexed her arm. "Hmm. Weird?" She flexed her hand again. "My arm feel… heavy?"
Lena's eyes narrowed, concern returning. "Red sun radiation," She said quietly. "It mimics Krypton's natural light spectrum. That's why Lex thought it could suppress Superman's abilities. Makes you like the rest of us."
Kara nodded slowly. "I forgot what it felt like…"
She stared at her arm, brows furrowed, flexing her fingers again. The strength was still there, but dulled. There was no pain, only the absence of a strength she'd grown so used to living with.
"Strange," She murmured. "I used to live under red sun, so many years. But now…" She trailed off and flexed her hand again, the differences between her arms were immeasurable. "I don't think I remembered how small I felt back then."
Strength returned to her arm as Kara let out a slow breath and gave a small, shaky smile. Then she considered returning the device before turning to Lena.
"May I keep this?"
Lena considered the small silver device still cradled in Kara's palm. Then she gave a slow nod. "You can keep it. Anything Kryptonian in here technically belongs to you." She crossed her arms, her tone still practical. "Just… maybe don't use it in the middle of a crisis?"
"Only when I need to look presentable," Kara grinned, placing the tanning gun back to be picked up later.
Lena gave a small smirk. "If you spot anything else from your homeworld, it's yours. We're not interested in locking away heritage, just danger."
Kara's expression sobered at that. She walked slowly along the nearby shelves, stopping to examine a series of similarly shaped devices. Sleek, gun-like objects arranged in neat rows. Each had varying construction. Different alloys, different grips, different energies humming faintly beneath the glass.
She inspected one with a jagged barrel and a dull green light pulsing along its spine, then another with a spiral-shaped emitter like a corkscrew. Kara frowned and shook her head.
"These are not Kryptonian," She said finally. "At least… not ones I recognise. These feel different. Crude. One of them smell like ozone and tar."
"Why is it always guns?" Lena muttered. She stepped beside Kara, studying the lineup with an arched brow. "You go across half the galaxy, dig through a hundred civilisations, and half of them end up building weapons that fit in your hand."
Kara tilted her head thoughtfully. "Some things are simple. Tool to hurt, or protect."
"A sword is a sword, even when it glows and talks," Lena mused. Then she gestured broadly to the room. "And isn't it strange how many aliens look humanoid? Like us, I mean. Two arms, two legs, one head, upright spine. Most are bipedal. Some around here take it as proof of a god."
Kara gave a soft laugh under her breath. "E'a var talon Vey'Anur…"
"What was that?" Lena turned slightly.
Kara smiled gently, brushing her fingers across the edge of a containment case. "Kryptonian. A phrase from scholars. Roughly… 'life echoes life.' Idea was, same looking species are more chance to finding each other. To recognise self in similar alien. To adapt. So more 'humanoids' mix. Non-humanoids don't blend in as well. Probably keep to themselves, or find other similar aliens."
"I guess that makes sense." Lena pondered.
"Also," Kara continued, "Most humanoids come from planets like Earth or Krypton. Same kind of gravity, air, pressure, light. So life, plants and animals. Biology all converges. Similar evolution, similar problems. Similar solutions…" She looked to the many gun-shaped devices lining the halls. However, she quickly turned back to Lena with a smile. "That's why alien animals sometimes look familiar, also."
"You mean Krypton had animals like Earth?" Lena's brow lifted slightly.
Kara nodded. "Some were… very different. But some not so different at all. I had never seen anything like cows. Very cute animals. Should not eat. But dogs? Very similar."
"Wait," Lena blinked. "Krypton had dogs?"
Kara had a soft, fond smile tugging at her lips. "Yes."
"Did you have a dog?"
Kara hesitated a second. "…Yes."
"What was his name?" Lena leaned in, curious now.
Kara shifted on her heels and mumbled, "…K-Krypto."
"You're kidding." Lena stifled her laugh, trying to appear professional. "You named your dog Krypto? Isn't that like someone here naming their dog 'Eartho.'"
Kara's cheeks flushed bright pink. "I was four..."
Lena laughed again, leaning against the edge of a sealed container for balance. "Please tell me he had a cape."
"He did not have cape." Kara snapped, trying not to smile. "…He always shook it off when I tried."
"Oh my god."
Kara rolled her eyes, muttering under her breath in Kryptonian. Lena didn't ask for a translation this time, she was pretty sure it wasn't flattering.
----------------------------------------------------------------------
The rest of the day passed in a blur of light, metal, and questions.
After their run-in with the tanning gun, Kara stuck closer to Lena's side, still wide-eyed but a bit more cautious. She stopped picking things up without asking.
Not that it helped much.
The vault offered no roadmap, no neat labels, no catalogued inventory, no way to tell if something was a universal translator or a planetary doomsday device. Kara quickly found herself paralysed by the sheer variety. Every row was packed with strange, gleaming shapes, humming softly or pulsing like sleeping hearts.
Every time she reached toward something, she stopped. What if it exploded? What if it turned her into a bug?
Lena noticed the hesitation.
"You're allowed to touch things," She said dryly, sifting through a crate filled with crystalline rods, "Just… with your brain on."
"I don't even know what I am looking for," Kara admitted, glancing helplessly down a shelf of curved glass objects. "They all feel like… like they're waiting explosion."
"They probably are," Lena muttered, picking up what looked like a long, sleek baton with two humming notches on either end. She examined it closely, then tapped it lightly against her palm. It vibrated once. She set it down. "Still too warm. Let's tag it and store it for later."
And so they began to make a system. It was crude, imperfect, but functional.
Obvious weapons were separated first. Handguns humming with unspent energy, sleek rifles with unfamiliar trigger mechanisms, a serrated blade that crackled with electric heat the moment it left its sheath. Lena directed Kara to help transfer these into a reinforced holding unit.
"This one has safety," Kara said at one point, pointing out a glowing alien sidearm with a magnetic seal.
"It also has a kill count etched into the grip," Lena replied. "Let's not test it."
Not everything was dangerous. Some items made Kara laugh outright.
Like the spherical device that, when activated, emitted warm air with the faint scent of citrus.
"Hairdryer?" She guessed, holding it to the side of her head. "Very nice airflow. Would recommend."
"More like a scented heater?" Lena considered, only half paying attention. "Could imagine a lot of people making use of it during winter."
Another object, a fist-sized polyhedron with shifting outer panels, seemed menacing at first until they realised it was just a portable lamp. Soft bioluminescence glowed in gentle blues and greens, lighting up Kara's face like firelight.
"It's pretty," She said, mesmerised. "I'd keep it next to bed."
"Maybe turn it off until we know why the light is emitting," Lena replied. "Could be a large tracking beacon? Doubt any signal is getting out of here, but you never know."
The earlier tension the day started with had thinned out into something more collaborative, maybe even friendly, if Kara believed hard enough. Kara asked questions. Lena answered, or admitted when she didn't know. Occasionally, their guesses overlapped.
A few of the items reacted to her. One lit up in her presence and then shut down the moment she walked away. Another attempted to inject Kara with a syringe the moment she picked it up, thankfully breaking on contact with her skin. Lena made note of those.
By the end of the day, they had created three distinct piles:
Definitely weapons: Tagged, sealed, and locked in containment behind two extra security fields.
Definitely not weapons: Hairdryers, lamps, tools, and two items Lena suspected might be alien kitchen equipment.
Look like weapons but not sure yet: Which included a curved staff that Kara swore was a ceremonial baton, but Lena argued might actually be an energy whip without a power source.
Kara still insisted it was a baton.
"Why does everything with handle have to be death machine?" She asked, twirling it playfully through the air, pretending to conduct music.
"Because people are death machines," Lena said. "They build what they are."
It was said so simply, so matter-of-factly, Kara frowned at how bleak the woman sounded.
Eventually, Kara noticed how dim the vault had become. A glance at her communicator made her blink. "It's almost midnight?"
"I lost track around nine," Lena said without looking up. She was still scanning the last of the "not harmful but vaguely ominous" pile.
Kara stood up from where she'd been cross-referencing glyphs on two separate gauntlets. She rolled her shoulder, then smiled sheepishly. "We should go home, yes?"
The pale hum of containment fields faded as Lena snapped the final registry closed and set the scanner down with a tired sigh.
"I think…" Lena began, running a hand through her hair, "...we've earned food. And maybe sleep. Definitely sleep."
Kara perked up, stretching her arms over her head. "Yes, yes. Sleep is a must."
They made their way back down the long aisle of containment units. The massive vault door loomed in the distance, still cracked open from earlier, cool air brushing against their faces as they approached. Lena keyed in a brief shutdown sequence, and the system's deep whirring subsided as containment protocols entered standby.
Kara looked over her shoulder at the modest chaos they'd left behind, half-sorted crates, tools still out, three tagged piles clearly marked but not yet relocated.
"Should we clean up?" She asked.
Lena pressed her hand to the biometric pad again. "No. No one else comes down here. I'd rather not waste time undoing everything we actually accomplished."
The vault door began to close, a low rumble vibrating through the floor as the massive locking arms began their slow spin.
Kara hesitated a moment. "Why don't you have more help?"
"You mean why haven't I hired a small army to comb through decades of dangerous, alien contraband?" Lena looked at her sidelong.
Kara nodded, genuinely curious.
Lena exhaled. "Because I can't trust a small army. I can't even trust a small team. And even the ones who are vetted tend to get too curious and end up touching a ball that gives you cancer." Kara's eyes widen at that. Lena waved the comment off with her hand. "Don't worry, we removed the cancer orb last year, and Alan's already in remission."
Kara felt like she should still worry, but chose not to say anything.
"Truth is, I was days from writing off the entire vault," Lena added, her voice quieter now, "Sealing it permanently. Then you came crashing through my labs." She offered a faint, knowing smile. "Kind of hard to ignore fate after that."
Kara's face flushed with colour, rubbing the back of her neck. "Right… sorry about that."
The elevator hissed shut behind them. Silence fell as it began to rise, up and up, far from the buried tombs of alien mystery.
When the doors opened again, they stepped out into Lena's sleek office, bathed in the cool blue glow of the city beyond her tall windows. Night had deepened over Metropolis. The skyline shimmered like polished chrome.
"I'll call it here," Lena said, tossing her security badge onto the desk. "You can fly from the balcony if you want. Save yourself a few thousand stairs."
"I need sign out at security desk, though." Kara shifted awkwardly, thumbing back to the elevator. She wanted to mention it before the long ride to the top floor, but became nervous. "Um, Protocol. Yes?"
Lena gave a sharp laugh, not even bothering to turn. "I'm the CEO, Kara. I am protocol."
Kara gave a sheepish smile as she moved toward the far corner of the room and turned her back. A swirl of warm air and red fabric later, Supergirl stood in Kara's place, brushing a strand of hair behind her ear.
"Well… thank you," She said softly. "For trusting me. For letting me help."
Lena nodded once, smiling at the emblem on Kara's suit. "Thank you, Supergirl." She gave a lazy two-finger salute, already moving to a bottle of something on the back wall of her office.
Kara gave her a small salute in return, then turned and stepped onto the balcony. One last glance over her shoulder. She still wasn't quite sure what to make of Lena Luthor. A smile exchanged between two women who weren't quite friends, but weren't just colleagues either.
And then, with a burst of air, she launched into the night.
------------------------------------------
Supergirl soared through the clouds, the night air biting cool against her skin. Gotham was a different beast beneath her, no gleaming spires, no soft golden hues. Just sharp rooftops and a tangle of shadows threaded by flickering lights.
Even at this hour, it was a noisy city, but no one was calling out for any immediate help, so Kara could focus on landing in her bedroom window and hopefully getting a few hours of sleep before she returned.
Then, she saw it.
A sharp beam cutting through the sky. Brilliant white against the clouds. The Bat-Signal.
Kara only knew about it through its reputation. She hadn't seen it used once since moving to the city, and none of the Bat-Family had even mentioned it when they talked about their work. Curiosity got the better of her in the end.
Supergirl angled downward, descending fast. The closer she came, the more oppressive the city felt. But she landed with grace, her boots clicking softly against the rooftop of the Gotham City Police Department.
Only one man was standing by the signal.
He was older, coat flaring at the edges, white in his beard, eyes tired. The man regarded her with a glance, one that hovered somewhere between hope and disbelief.
"Oh, I heard you were in town," He said simply, dropping a cigar from his mouth and stamping it out. The man sighed, reaching up and flipping a switch. The beam cut off abruptly, and the rooftop fell back into shadow.
"Well," He muttered, more to himself than to her. "This'll have to do."
Supergirl tilted her head, uncertain. "Is something wrong? I can help, if-"
"I hope so," He said, looking her straight in the eye. "Because come sunrise, six people are going to be dead."