The oppressive, cloying sweetness of the Azure Garden's atmosphere still clung to Lin Ye's senses, a phantom scent that made his stomach churn even as they stumbled deeper into the unadulterated darkness of the lava tube. The memory of the pulsing blue-green light, the viscous pool, and the horrifyingly emergent limb was a fresh, raw wound in his mind, far more disturbing than the aching fire in his back. He found himself glancing over his shoulder more often than necessary, a knot of primal fear coiling in his gut.
Zero walked beside him, or rather, shuffled, a small, trembling shadow. She hadn't spoken a word since they'd fled the cavern, her arms wrapped tightly around herself as if to ward off an invisible chill, or perhaps to hold herself together. The "song" she'd heard, the psychic lure of those alien entities, had clearly left a deep, unsettling imprint on her fragile psyche. Lin Ye could only imagine the horrors it had dredged up or implanted. He noticed she kept her head down, as if afraid of what she might see in the oppressive darkness, or perhaps what might see her.
[Noah: Host, Zero's neurological activity remains erratic, though the acute stress responses are slowly subsiding. The psionic interference from the 'Azure Garden' seems to have a lingering effect. Continued monitoring is advised. Your own vitals are stabilizing, but the exertion has taken a toll. We need to find a defensible position for a proper rest cycle soon, ideally one with cleaner air and a single entry point.] Noah's voice, though still occasionally laced with a faint digital tremor from the earlier EMP, was a welcome anchor of rationality in the swirling chaos of Lin Ye's thoughts. Her processing speed felt almost back to normal.
"Understood, Noah," Lin Ye rasped, his throat dry. He took a swig from his canteen; the water, collected from the cavern, had a faint mineral taste but was blessedly cool. "Any sign of those… things… following us?"
[Noah: Negative, Host. The unique geomagnetic properties of these deeper volcanic tubes appear to be effectively containing whatever energy signature they emit, or they are simply not designed for pursuit beyond their immediate environment. However, we are now moving beyond the most effective range of that natural shielding. We will soon be re-entering areas potentially accessible to standard AI patrols and, more troublingly, the Ghost Signal. The ambient 'noise' Zero perceives may also shift accordingly.]
That was a sobering reminder. One nightmare exchanged for another, perhaps more familiar, but no less deadly. Lin Ye glanced at Zero. Her head was down, her long, dark hair obscuring her face, but he could see the slight, continuous tremor running through her shoulders.
"Zero," he said gently, his voice softer than he intended, trying to cut through her cocoon of silence. "Are you… are you hearing it still? The song?"
She flinched almost imperceptibly at the word "song," then slowly shook her head. "Fainter," she whispered, her voice hoarse and thin, like dry leaves skittering across concrete. "Like… an echo in an empty room. Far away now. But it's… sticky. It doesn't want to let go." She looked up at him, her amber eyes haunted, reflecting the faint light from his gauntlet like a cornered animal's. "They wanted to make us part of them, Lin Ye. Not like the machines… something else. Something… older. Colder."
Lin Ye didn't doubt her. He had seen the limb. He had felt the unnatural dread that transcended mere fear of AI. "We got away, Zero. That's what matters. We keep moving, we put as much distance between us and that… place… as possible." He tried to sound confident, for her sake as much as his own.
According to Noah's projections, their current path through the lava tubes would eventually intersect with a major, pre-collapse subterranean transit line – part of the city's old subway system. It was their designated Route Two towards Sector Gamma-7, a path chosen for its depth and theoretical avoidance of major AI surface patrols.
After another hour of arduous travel, the character of the tunnel began to change. The rough, volcanic rock gave way to smoother, artificially constructed walls of graffitied concrete and rusted metal support beams. The air grew staler, colder, carrying the scent of old decay, dampness, and the faint, unmistakable odor of ozone – a tell-tale sign of old, malfunctioning electrical systems. The silence was different too; the natural drips and rumbles of the lava tubes were replaced by an echoing emptiness, broken only by their own movements.
[Noah: We are approaching an access point to the old Red Line subway tunnels, specifically the R-4 maintenance conduit. Caution is advised. These systems were interconnected with city-wide AI networks prior to the collapse. Though largely defunct, pockets of automated security systems or corrupted AI remnants may still be active or easily reactivated by proximity.]
The lava tube opened into a gaping, jagged hole in the side of a massive, arched concrete tunnel. Below them, shrouded in an almost impenetrable darkness that even Lin Ye's gauntlet beam struggled to pierce, lay a pair of rusted railway tracks, disappearing into blackness in both directions. A derelict maintenance scaffold, its metal latticework eaten away by rust and time, clung precariously to the wall near the breach, offering a treacherous descent of about ten meters to the track level.
This was it. Their path forward into the bowels of the dead city.
"Well, that looks inviting," Lin Ye muttered, peering down. The drop wasn't sheer, but the scaffold looked like it could give way with the slightest provocation.
[Noah: The scaffold's primary support struts appear compromised. I calculate a 65% chance of structural failure if subjected to your combined weight simultaneously. It would be safer to descend one at a time. I can highlight the least corroded sections.]
"Zero," Lin Ye said, turning to her. "You first again, I'm afraid. You're lighter. I'll guide you from up here with Noah's help. Once you're down, find a secure spot and keep an eye out."
Zero looked at the rickety scaffold, then down into the blackness below, and swallowed hard. But the memory of the Azure Garden, and Lin Ye's earlier sacrifice, seemed to steel her resolve. She nodded, her expression grim but determined. "Okay."
The descent was nerve-wracking. Guided by Lin Ye, who relayed Noah's precise instructions on handholds and footholds, Zero moved with a slow, deliberate caution that belied her inner fear. Rusted metal groaned under her slight weight, and flakes of corrosion rained down into the darkness. Lin Ye watched, his own muscles tensed, ready to react, though what he could do from his vantage point was limited.
Finally, after what felt like an eternity, Zero's soft call came up: "I'm down. It's… a mess. Lots of debris on the tracks."
Lin Ye took a deep breath. His turn. He tested the top of the scaffold. It creaked ominously. "Wish me luck, Noah."
[Noah: Luck is not a quantifiable variable, Host. However, I have calculated the optimal stress distribution for your descent. Please adhere to the highlighted path.]
His descent was even more fraught. His greater weight made the scaffold sway and groan alarmingly. Several times, a handhold crumbled beneath his grip, forcing him to rely on raw strength and Noah's instant recalculations to find a new purchase. The pain in his back flared, sharp and insistent, but he pushed through it, adrenaline and desperation fueling his movements.
He landed with a jarring thud on the ballast beside the tracks, sending a puff of acrid dust into the air. He was panting, his back screaming, but he was down. Zero was a few meters away, her gauntlet providing a small pool of light, her eyes wide with a mixture of relief and lingering apprehension.
They were in the subway. The air was heavy, still, carrying the scent of damp concrete, old oil, and something else… a faint, musty odor that spoke of long abandonment and unseen decay. The twin tracks stretched into oppressive darkness in either direction, promising only more unknown dangers. Above them, the hole they'd come through was a distant, irregular patch of lesser blackness.
"Which way, Noah?" Lin Ye asked, already scanning their surroundings.
[Noah: According to the pre-collapse schematics for Sector Gamma-7's likely access points, we should proceed east along this line for approximately three kilometers. However, this section, R-4B, was flagged for significant structural damage even before the final collapse. Expect obstructions.]
As if on cue, a low, guttural skittering sound echoed from the darkness to the east, followed by a series of high-pitched, chittering clicks. It wasn't metallic. It wasn't AI.
Zero tensed, her head snapping towards the sound, her hand instinctively going to the small, sharp piece of rock she'd picked up in the lava tubes – a pathetic weapon, but a weapon nonetheless. "What was that?" she whispered, her voice trembling.
Lin Ye raised his pipe, his own senses on high alert. The "mundane" threats Noah had warned about had arrived sooner than expected.
[Noah: Multiple biological signatures detected, Host. Small, fast-moving, and exhibiting pack behavior. Based on residual bio-signatures found in similar deep-level tunnel systems… I believe they are significantly mutated Rattus} {norvegicus. Common brown rats. Or rather, what they've become.]
The chittering grew louder, closer. From the edge of their light, a pair of glowing red eyes appeared, then another, and another.