Chapter Text
Chapter One: The Thirteenth Experiment
It was late, the kind of hour when even the hum of L-Corp’s servers sounded like a lullaby. Most of the building slept, but Lena Luthor rarely did.
She was reviewing research data when a soft ping cut through the silence. A notification window blinked in the corner of her screen:
“Legacy Protocol Triggered — Redirected Lex Luthor Communication Packet Detected.”
Lena froze. She hadn’t seen that alert in months. She’d built it as a failsafe to protect herself, to catch anything Lex sent through his private channels before the authorities could scrub it. It had gone off several times since his imprisonment, and always filled her with dread; she had quietly passed most of the information she had learnt to the Prosecutor in charge of Lex’s case, some she had hidden. She’d only hidden what couldn’t be proven in court, or what was too vile to be legal but sadly was. She had the right to protect herself.
Her fingers hovered over the keyboard, then moved quickly, decrypting the data. Lines of code resolved into a transmission, short, but for his direct attention. The message had been auto-sent to an unregistered server under Project Prometheus- Experiment 13
Then she saw the attached data: Subject Status: Viable. Accelerated growth cycle suspended. Awaiting further instruction.
Her pulse stumbled. “Subject?”
Her stomach dropped. She had never come across the ‘Project Prometheus’ title before, but Lena could guess from the name that it was some kind of weapon or attack against Superman. After all, Prometheus stole fire from the gods to uplift humanity, and there was only one being that Lex ever referred to as a god. Though his tone was almost always mocking or disgusted
She opened the routing file and traced the alert back through the system that she had set up and found the coordinates of the alert, an isolated industrial park on the outskirts of National City.
“Damn it, Lex…” she whispered, rubbing her temples. “At least it’s close,” she really couldn’t have hidden a trip to Metropolis right now.
Lena stood so fast her chair rolled back. She grabbed her coat and bag, phone already in hand.
“Security, bring my car around,” she said, voice low but urgent. “I won't need my driver.”
For a heartbeat, she hesitated, not out of fear, but of instinct. There were things her brother touched that even she didn’t want to find. As much as what he had done had broken her heart, a part of her would always be the little grieving orphan he’d once made feel welcome, and that little girl still loved him. Seeing more of his dark deeds would hurt.
Then she steadied herself, eyes hardening. “If Lex made something… I’ll see it before anyone else does, and if I can, make it right.”
The road to the industrial district was nearly deserted, a skeleton of warehouses and empty loading bays half-swallowed by the dark. National City slept, unaware of the secret beating beneath its veins.
Rain slicked the streets, a rare thing in National City. Lena drove with both hands clenched on the wheel, headlights carving twin tunnels through the mist. The wind off the bay smelled like rust and ozone. When she finally pulled up to the coordinates, she sat there for a long moment, engine idling, the rhythmic swipe of the wipers the only sound.
Lena’s headlights cut a long beam through the rain as she pulled up to the coordinates. The warehouse looked ordinary, squat, windowless, its concrete walls slick with rain, a disused freight depot owned by one of a thousand shell companies that had once fed Lex’s twisted empire. But the moment she stepped out of the car, she knew better. The air hummed.
She stood there for a moment, her coat plastered against her legs, staring at the faint vibration underfoot, not the mechanical thrum of power lines but something deeper, older. A frequency she almost recognised.
“Lex, what have you done?” she whispered.
She circled the side door, testing the keypad. The lock yielded too easily under her hand, and Lena wondered if this was a trap, one of Lex’s little games. She’d broken into enough of his vaults to know that sometimes the monsters he built weren’t metaphorical.
For a second, she thought of turning back. She could call the DEO, let them claim jurisdiction, and stay safely detached. But she pushed the thought down. Whatever waited in there was hers to face. Hers to set right.
It was a lab, and though Lena always found comfort in the controlled environment of a lab, this one was just wrong, like a ghost’s imitation of a hospital. White tiles. Chrome tables. The faint hiss of filtration vents that hadn’t been serviced in years but somehow still ran. It looked a little like how the movies or television portrayed a morgue.
She moved slowly, eyes scanning for familiar insignias, and found them.
Cadmus. DEO. Copied, mislabeled, and hidden among medical supply inventories. She felt her pulse trip, her hand braced against a counter as she realised where she was.
Lena crossed to the terminal, fingers flying as she decrypted the first batch of files. The data scrolled fast: alien cell samples, radiation stability graphs, DEO frequency intercepts, even telemetry from when Fort Rozz had crashed to Earth.
A chill crawled up her spine.
“This wasn’t just some private obsession,” she breathed. “He built it here on purpose.”
Her mouth went dry. “National City… of course.”
She could almost hear Lex’s smug tone in her head, that mixture of arrogance and poetic spite. He hadn’t chosen the location because of Supergirl. She hadn’t even shown herself yet when the lab was built. No, he’d chosen it because this city was already a nexus:
The DEO’s West Coast headquarters and the high extraterrestrial population that they hunted.
The lingering Fort Rozz radiation field, rich with Kryptonian residue, and tech
To Lex, that meant one thing: access. Proximity. Potential.
She opened the folder for the project that had brought her here. Project Prometheus- Experiment 13, and her stomach turned at the name of the first of the three folders:
Primary Objective: Hybridisation — Kryptonian genome (Superman) × Human superior genome (Luthor).
The other two were slightly less concerning.
Monitored DEO channels.
Utilisation of Fort Rozz ambient radiation for cellular stabilisation.
Lena swayed where she stood.
Her gaze flicked toward the rows of cylinders at the far end of the lab. The realisation crawled through her veins like ice.
Lex hadn’t built this lab near the DEO for protection; he’d built it to feed on them. To intercept their research, their scans, their prisoners. To get to a Kryptonian before the government could.
And somewhere in here, that hunger had finally succeeded.
Lena’s pulse beat loud in her ears as she forced herself forward, through the maze of sterile metal and dead terminals, until the first cylinder came into view, then another, and another.
The dread that had been coiling in her gut turned to horror.
The overhead lighting flickered on as she stepped further in, a harsh, clinical white, casting long shadows that stretched like bony fingers along the rows of glass and steel tanks.
Each chamber she passes is a grim showcase of failed attempts. Some tanks hold tiny forms, only a foot tall, curled up and suspended in a pale, bluish fluid. These fetal remains never had a chance, and the glass of their chambers is clouded with faint condensation, as if the room itself is trying to breathe out the horror.
As she moves further down the line, the tanks contain progressively larger figures. One chamber holds the preserved body of a toddler-sized clone, its eyes forever closed, its torso malformed, its ribcage exposed as though it had grown without skin, its limbs slightly contorted in the eerie stillness of suspended animation.
Lena used to stand at Lex’s shoulder when she was nine, watching him rebuild circuit boards and whisper equations like prayers. He’d told her once that brilliance was its own morality, that if you were clever enough, right and wrong were just obstacles to innovation.
For years, she’d believed him.
Standing in his lab now, with the ghosts of his genius floating in tanks, she wondered if that had been his first experiment, testing how much of her soul he could reshape.
The next tank reveals a slightly older child’s form, delicate but lifeless, a three-year-old with the marks of autopsy showing clearly on his preserved remains; the marks looked wrong to Lena somehow. She reached out and pressed a finger to the dark screen displayed on the chamber covering the dead child's genitals; she doubted the placement was for the departed's benefit. At her touch, the screen lit up.
SUBJECT 12: Viable musculature, limited cognition. Deemed unfit. Disposal by vivisection. Recordings archived.
Now, reading it, Lena understood why the Incisions looked wrong, and she wished she didn’t. They were red, dead tissue doesn’t do that, the boy had been alive when they had cut him open. And they had recorded it. Lena turned away, hand over her mouth and stumbled to the wall, breathing through the need to vomit. Her hand moved from her mouth to her chest as though to shield her heart from the horror around it. She stood there so long, the wall her only support as she fought for control of her body's reaction, that the lights went out above her, the sensors assuming that she had left the lab.
It was the memory of the alert’s message that got her moving again: “Subject Status: Viable.” Subject 13 was viable, but there was a fault in the chamber. She had to find him, and help him.
Finally, she reached the last chamber. Housing a four-year-old boy, his small body covered in a network of electrodes. Each pulse sent through those wires makes his limbs twitch slightly, a grotesque parody of life meant to stave off muscle atrophy. Over his head, a neural interface glows faintly, feeding him streams of data, a poor substitute for a childhood. He is the last viable experiment, a fragile promise of what Lex hoped to perfect, surrounded by the silent, eerie testament of all the failures that came before.
He looked both heartbreakingly human and impossibly fragile.
Lena took a step closer, hand rising to the glass. “You’re safe now,” she whispered, though she didn’t believe it.
Her reflection wavered across the surface, pale, hollow-eyed, trembling. She barely recognised herself.
Lena’s hands were still trembling when she pulled her phone from her pocket.
Her first instinct was to call the DEO. But she knew how that would end: containment, weapons protocols, a boy dissected by people only slightly less monstrous than Lex.
Her second instinct was to call Kara.
Her fingers hovered over the screen for only a second before she hit the contact. The line clicked almost immediately.
"Kara?" Lena’s voice cracked despite herself, urgent and low. "I need you to listen carefully. I’ve found one of Lex’s labs. You…" She glanced at the boy in the tube, lowering her voice further. "You have to contact Supergirl. Tell her to come here. Right now. And she has to come alone."
On the other end, Kara sat bolt upright on her couch. "Lena, what’s wrong? Are you safe?"
"I’m fine," Lena said too fast, and too sharp, her voice full of splintered glass. "I’m fine. But there’s something here. Something Lex left behind. It’s… It’s a child, Kara. And I swear, if anyone else finds this place before Supergirl does, the boy is as good as dead."
She hadn’t meant to say that. Hadn’t meant to start with that. But once the words were out, more tumbled after them like water breaking through a dam.
"I didn’t know," she whispered, her breath hitching. "I didn’t know what he was doing. He used Fort Rozz, and Cadmus data, and DEO intercepts. All of it. And there are bodies, Kara. Children. Twelve of them."
She swallowed hard, but the lump in her throat didn’t go away. "One of them is still alive. Four years old, maybe. In a tank, hooked up to wires like he’s a machine. And I think, I think Lex used his own DNA. And Superman’s. My brother made a child just to see if he could."
There was silence on the line, but Lena barely noticed it. She pressed a trembling hand to her mouth, trying to slow her breathing. She didn’t remember sitting down, but now the cold polished concrete of the lab floor was against her hip.
"I didn’t mean to say all that," she muttered, voice smaller now, breaking apart. "I just, I couldn’t keep it in. Not after seeing them. Not after reading what he did. I thought I could handle it, but…"
Her voice trailed off into a silence weighted with grief.
On the other end, Kara pressed her hand to her chest, heart thundering. She recognised that voice, the one Lena used when her walls cracked. The one she never let anyone else hear.
She lowered her own voice, soft but certain. "Lena. I’m still here. I’m going to get Supergirl. Stay there. Don’t let anyone else near that lab. She’ll be there soon."
Lena nodded shakily, then remembered Kara couldn’t see her. She forced her voice to steady. "Thank you. I knew I could trust you."
Her thumb hesitated over the screen before she added, almost as an afterthought, almost like a confession:
"I needed you to be the one who hears it first."
Then she hung up.
Silence closed around her again, heavy and echoing. For a moment, she just sat there, phone still clutched in her hand, listening to the hum of the filtration vents and the faint, rhythmic pulse of the tank behind her.
She could have left then. Waited outside for Supergirl.
But her eyes kept drifting back to the terminal on Subject 12’s chamber, its display still dim and waiting.
She told herself it was for proof. That she needed to know how far Lex had gone, whether he had truly…
Her throat tightened. She couldn’t finish the thought.
Lena stepped closer, fingers brushing the keys. The screen brightened, text rippling into focus:
SUBJECT 12: Viable musculature, limited cognition. Deemed unfit. Disposal by vivisection. Recordings archived.
Lena stared at the words until they blurred. Then, despite herself, she tapped ARCHIVE ACCESS. A list of audio files appeared, each stamped with a date and and the last file a video recording.
The first one played automatically.
[Recording 12-A | Cognitive Assessment — Month 36]
LEX LUTHOR: “Can you tell me what colour this is?”
SUBJECT: “R-r-red.”
LEX: “Good. And this?”
SUBJECT: “B-blue.”
A pause. The faint sound of the child breathing too fast.
LEX: “How many sides does a triangle have?”
SUBJECT: “Three.”
LEX: “And a square?”
SUBJECT: “Four.”
There’s a soft click of a pen against metal.
LEX: “You learned that from the flash cards?”
SUBJECT: “Y-yes, sir.”
LEX: “Recite the periodic table, beginning at hydrogen.”
The child hesitates.
SUBJECT: “H-Hydrogen, Hel-Helium, L-Lith-ium, Be-Beryllium, Bo-Bor-”
Lex cuts him off with a sigh. The chair scrapes back.
LEX: “Deficiency in verbal control. Motor hesitation persists. Emotional contamination noted.”
The next file loaded without her command.
[Recording 12-C | Creative Response Test — Month 37]
LEX: “I’m drawing a man on the board. Tell me who he is.”
SUBJECT: “Ya-You.”
LEX: “And this one?”
SUBJECT: (hesitates) “Mmm - mother.”
(The sound of a pen striking metal, sharp.)
LEX: “No. Try again.”
SUBJECT: “Ma- Mother.” (smaller, frightened)
LEX: “You have no mother.”
(the child whimpers)
LEX: “Do you know why?”
SUBJECT: (tiny voice) “ Ba- ba- Because… I’m ba-bad?”
LEX: “Because you’re not a person. Only people have parents. You are a construct. You are mine. And mine alone.”
(pause — Lex exhales, composed again)
LEX: “Terminate recording.”
Lena’s hand hovered over the console, the audio still echoing faintly through the lab. Lex’s voice, calm, patient, godlike, carried the same tone he’d once used on her when explaining the properties of thermodynamics.
But this time, it wasn’t knowledge he was sharing. It was doctrine.
She replayed the last line again:
“You are a construct. You are mine. And mine alone.”
Lena froze. The voice of the child, so small, so eager to please, still hung in her ears. Because I’m bad?
She pressed a trembling hand to her mouth. That was how the boy had understood himself, as a failure, as something unworthy of love because Lex had told him so.
The screen’s reflection glinted off her eyes as she whispered, “You couldn’t stand it, could you? That he saw you as human.”
Her mind raced through Lex’s old habits of control, the way he punished vulnerability. Even now, it made sense in that terrible, awful way that everything Lex did made sense to him. He hadn’t dehumanised the clones to maintain scientific distance. He’d done it because he couldn’t share divinity. Because if the child were a person, then Lex was just a man, and he would rather be a god alone than a human with company.
Lena’s voice cracked. “You were jealous. Of a child who would have loved you, if you’d allowed it.”
“Oh, baby boy, you were not bad,” she whispered. “And you are not his. You never were.”
[Recording 12-D | Termination Evaluation — Month 38]
LEX: “Cognitive plateau confirmed. Emotional instability unresolved. Subject associates test administrators with parental archetypes. Recommend disposal.”
The file ended with the sharp hiss of a door sealing. The last file started to load, the video file, [Recording 12-D | Vivisection — Month 38]. Lena shut it down; she would not subject herself to watching that. She could only offer a prayer that the child hadn’t known what was about to happen.
The moment she stopped the playback, the lab seemed louder, every hum and hiss magnified, as if the place itself resented her for turning away.
Lena’s hand was still on the console when she realised she was shaking. Her throat ached.
He’d called it “emotional instability.” A child’s stutter. A child’s attachment.
She stumbled back from the tank, one hand over her mouth. For a long moment, she stood in silence while the light over Subject 12’s chamber flickered, reflecting the pale curve of a small hand suspended behind the glass.
Lena turned toward the last chamber, toward Subject 13, and laid a hand against the cold glass.
“You’re not going to end that way,” she said softly. “Not if I can help it.”