She ran upward until the Vein could no longer contain her.
The climb became steep enough that gravity itself seemed offended by her persistence. Ramps gave way to broken stairs, stairs to nothing but angled debris she had to claw her way across. Her breath came in sharp, tearing pulls, every inhale scraping raw against her throat. The whispering guidance that had held her together for so long narrowed to urgency alone.
"Up."
"Do not stop."
Then the world broke open.
A gate ahead of her irised apart without warning, and light, real light, detonated into her vision. Not the sickly glow of maintenance strips or the anxious flicker of Vein-lamps, but a brutal, honest brightness that stabbed straight through her pupils and into her skull.
She cried out and stumbled forward, momentum carrying her through the opening just as the gate slammed shut behind her with a force that shook the ground.
Metal screamed.
Not an alarm. Not a system failure.
Scratching tore across the sealed door from the other side, deep and frantic. The sound of grinding pressure followed, as if whatever had chased her was testing the boundary between worlds with claws, with weight, with intent. The gate bowed inward by a fraction, just enough to remind her how thin the line had been.
Then it held.
She collapsed to one knee, palms pressed against stone that felt almost warm beneath her fingers. Her rifle slipped from her grip and clattered beside her, forgotten for a long moment as she sucked air like a drowning thing that pulled back to shore.
The scratching did not stop immediately.
It faded slowly, reluctantly, like something being dragged away from prey it had already decided belonged to it.
Silence followed.
A different kind that the Vein's.
Her eyes burned as they adjusted, tears streaking down beneath her mask as the brightness resolved into shape, depth, color. She blinked hard, lifting her head inch by inch.
And saw it.
The Deepstrata Metros.
The entrance sprawled before her like the mouth of a sleeping god, carved into bedrock and reinforced with ancient metal ribs now split and softened by time. Vest arches curved inward, leading down into darkness that felt deeper than absence. Old transit sigils, once sharp, once proud, were choked with moss and flowering growth that glowed faintly, not with electricity but with something closer to breath.
Life.
Actual, undeniable life.
Mice darted between fallen stones, their tiny bodies fearless in a way only creatures unburdened by memory could be. Rats followed heavier paths, bold and watchful, their nests woven into the hollows of rusted machines half-consumed by roots. Strange plants sprawled across the pathway, vines thick as cables, leaves veined with pale luminescence, flowers that opened and closed with slow patience as if listening to something below.
The air smelled different here.
Damp earth. Minerals. Something sweet and rotten and alive.
She had spent so long surrounded by machines pretending to be ecosystems that the real thing felt almost alien. The presence of growth pressed in on her senses, unsettling in its quiet confidence. Here, metal did not dominate. It yielded.
Entropy's touch.
TCOGE's breath.
M.A.R.S. spoke again, and for the first time since the chase began, his voice carried something like restraint.
[M.A.R.S.]
"This is as far as my dominance extends."
She pushed herself upright slowly, legs trembling as she took in the scale of the place.
[Fox] "You sound... distant."
[M.A.R.S.]
"I am. My reach within the Metros is severely limited. Entropy interferes with my propagation. Her influence disrupts machine cohesion. Signal fidelity collapses the deeper you go."
[Fox] "So you're blind."
[M.A.R.S.]
"Not blind. Muted."
She glanced back at the sealed gate, half-expecting it to shudder again. It remained still.
[Fox] "And what if whatever that was finds a way out?"
[M.A.R.S.]
"If you are concerned about it following you into the labyrinth, I wouldn't be so worried. There are many ways into the Metros. Few are accessible to what pursued you. Fewer still are survivable."
That did little to settle her nerves.
She rolled her shoulders, wincing as fatigue finally settled into her bones.
[Fox] "So this is where you let me go."
[M.A.R.S.]
"Not entirely."
She frowned.
[Fox] "What do you mean?"
There was a pause. Not a delay, but a gathering.
[M.A.R.S.]
"You will open your laptop."
She hesitated, then reached into her pack with stiff fingers, pulling the device free. It felt heavier than it had any right to be, like it had been waiting for this moment. She flipped it open, the hinge creaking softly in the open air.
The screen flickered.
Then it went red.
Not an error. A symbol bloomed across the display, concentric crimson rings pulsing slowly, deliberately, like a heart learning a new rhythm. Around them unfurled two pairs of stylized wings, angular and broken, framing the center as if guarding it from the edges of the world.
[M.A.R.S.]
"I will upload a significant portion of my operational consciousness into this device, approximately eighty-seven percent. This will reduce my external influence but preserve continuity."
[Fox] "That's—"
[M.A.R.S.]
"—the minimum required to assume control of Ecstasy's husk. Anything less would result in fragmentation too severe to maintain dominance."
She stared at the symbol, watching it pulse.
[Fox] "You're putting a lot of faith in me."
[M.A.R.S.]
"No. I am making a calculated sacrifice. Faith implies choice. I have none left."
Data began to scroll, not in lines she could read, but in movements she could feel, the laptop humming softly as if alive. The air around it seemed to vibrate, subtle enough she might have imagined it if not for the way her teeth buzzed faintly in her skull.
[M.A.R.S.]
"When you find the body, you will connect this device directly to the husk's interface. I will complete the transfer then. Until that moment, my ability to assist you will degrade."
[Fox] "How badly?"
He did not answer immediately.
[M.A.R.S.]
"Expect silence, or fragments. Echoes. Nothing more."
She swallowed, eyes drifting back to the Metros. The labyrinth below seemed to inhale, waiting.
[Fox] "And entropy?"
[M.A.R.S.]
"There will be no hiding from her. She is an intelligence that not only listens, but also feels. Given that she was birthed from your kind, she is not restricted by the need to calculate. The closer you draw, the more the world will resistyou."
She closed the laptop slowly, the symbol vanishing as the lid snapped shut. The weight remained.
[Fox] "Sounds welcoming."
[M.A.R.S.]
"You have always excelled in unwelcome places."
She almost smiled at that. Almost.
The plants near the entrance shifted as she stepped forward, leaves brushing against her boots without fear. Somewhere deeper inside, water dripped in a slow patient rhythm. The Metros did not feel dead.
They felt occupied.
She paused at the entrance, hand tightening around her rifle, the other resting briefly against the pack where the laptop waited, where most of M.A.R.S. now slept, vulnerable and silent.
[Fox] "Once I'm in there, you don't get to steer."
[M.A.R.S.]
"I never truly did."
She stepped into the darkness.
The light behind her faded quickly, swallowed by stone and living shadow. The entrance narrowed, the world above retreating until only the echo of her footsteps remained.
Ahead lay the Metros, a maze grown wild. A place where gods had bled into the soil.
And she walked into it alone.