78: Chapter 78 Promethium Criticality and Mutation Stance

The air in the lower abandoned city carried a metallic sweetness mixed with rust and ozone, feeling like swallowing sandpaper with every breath. A piercing red warning flashed on Lin Yuan's tactical visor; the Promethium reserve reading sat at 2.1%, the numbers slightly distorted by electromagnetic disturbances in the Phase Interference Zone as if being tugged by invisible fingers.

Carrying the wreckage of THRONE-01 on his back and dragging his younger brother Lin Chen with his right hand, he moved through a collapsed mag-rail tunnel. Three hundred meters behind them, the ear-piercing sound of metal scraping against rock never ceased—it was the sound of the Reaper Mother's six mechanical legs climbing the walls of the vertical shaft. The four-meter-tall war machine was adapting to the complex terrain of the lower levels, its biosensors emitting high-frequency pulses in the interference zone. Each scan sent a needle-like sting through the Silver-wire Network at the back of Lin Yuan's neck.

"Left," Lin Chen suddenly spoke, his voice hoarse.

Lin Yuan did not hesitate, immediately ducking into a gap in the pipes on the left. Almost in the same second, a brilliant white particle beam pierced the spot where they had just been standing. The concrete vaporized instantly, releasing a pungent smell like burning sulfur. Moss on the pipe walls was scorched into charcoal, falling away in flakes.

"How did you know?" Lin Yuan lowered his voice, shielding his brother behind him while adjusting the position of the THRONE-01 wreckage on his back. That metal shell, which once belonged to an Astartes, was rising and falling slowly and rhythmically on his back, as if breathing. Dark red liquid metal seeped from the joint crevices, dripping onto Lin Yuan's shoulder armor. It was hot enough to make his muscles tense, yet it didn't burn his skin, instead leaving behind dark red patterns that cooled rapidly.

Lin Chen didn't answer. His right hand was trembling, and the 09-Ω pattern beneath the skin of his neck emitted a faint blue light. Through the one-way neural empathy link, Lin Yuan could feel the pain transmitting through his brother's neural dendrites—a fine, continuous burning sensation, as if someone were embroidering his spinal cord with red-hot needles. But at this moment, this pain was mixed with a colder signal, pointing toward a specific spatial coordinate behind them.

"It's locking onto my biosignals," Lin Chen sent the thought through the empathy link, more direct and fragmented than speech. "Like... a bell."

Lin Yuan's pupils constricted slightly. In the upper right corner of his vision, the transparency of the White House hallucination had climbed from 25% to 30%. The second hand of the bronze clock ticked across his retina, accompanied by the auditory hallucination of a rhythmic clicking. The time displayed 3:17:15, but the second hand moved significantly slower than reality, as if dragged through a viscous liquid.

They passed through the mag-rail tunnel and entered the Core Zone of the lower abandoned city. The architectural structures here bore the hallmarks of pre-war military facilities, with heavy concrete walls riddled with bullet holes and radiation scorch marks. Rusted remains of automated weapons were scattered across the ground, along with mechanical limbs torn apart by brute force—not belonging to the Reapers, but to an even older model.

Lin Yuan's breathing became rapid. Promethium reserves dropped to 1.8%, and black spots began to appear in his vision. He had to make a choice, and he had to do it within ten seconds.

Tactical calculations whirred through his mind. Option A: Reserve the final 0.5% of Promethium for his brother's potential worsening condition or emergency medical needs; survival probability 12%. Option B: Inject the Promethium into the THRONE-01 wreckage and gamble on its mutation generating a defensive mechanism; survival probability 47%.

There was no Option C.

Lin Yuan stopped and laid the THRONE-01 wreckage flat on a relatively intact alloy platform. The chest armor of the wreckage was completely open, revealing the complex neural conduits and cooling systems within. The machine spirit core, which should have been dormant, was now emitting a dark red glow that pulsed with that eerie "breathing" rhythm.

"Brother, don't let me down," Lin Yuan whispered, his voice as raspy as sandpaper.

He pulled out the Promethium injector from his waist and plunged the needle into the power interface of the THRONE-01 wreckage. The final 0.5% of Promethium was pumped into the mutated mechanical body. The moment the injector emptied, the power reading on the system interface plummeted to 1.6%, and a glaring red warning nearly occupied his entire field of vision.

The wreckage of THRONE-01 began to tremble violently.

It wasn't the shaking of a mechanical failure, but a more primitive, biological convulsion. Dark red liquid metal erupted from every crevice like living blood, condensing into filaments in the air before rapidly weaving into a web. The metal threads emitted a high-frequency hum, resonating with the background noise of the Phase Interference Zone.

Lin Chen suddenly let out a muffled groan and collapsed to his knees. His right hand clawed uncontrollably at his neck, where the 09-Ω pattern flared with a blinding blue light. Through the neural empathy link, Lin Yuan felt his brother make a resolute choice.

Lin Chen's fingers dug into the Neural Inhibitor interface beneath the skin of his neck, forcibly tearing out the fuse that prevented neural signal overload.

Agony flooded back into Lin Yuan's perception through the empathy link like a tide, making his vision go dark. But within this intense pain, he sensed the high-frequency bioelectric pulses released by Lin Chen. Those pulses created a harmonic with the dark red liquid metal seeping from the THRONE-01 wreckage, acting like an invisible key sliding into a keyhole.

In the tunnel behind them, the Reaper Mother's movements lagged for 0.3 seconds. Its biosensors were jammed by this interference—a mix of mechanical and biological signals. Its six mechanical legs slipped in place, producing a sharp noise of scraping metal.

"Go!" Lin Yuan gritted his teeth and hoisted THRONE-01, dragging the nearly exhausted Lin Chen toward the end of the tunnel.

The dark red liquid metal didn't recede; instead, it hovered in the air, flowing along with the movement of the THRONE-01 wreckage to form an irregular barrier. As they rushed through a collapsed archway, Lin Yuan saw their target: a heavy radiation shielding door, covered in dust but still bearing a recognizable, massive embossed emblem.

The Imperial Aquila symbol. The wings of the double-headed eagle were spread, its beaks clutching gears and lightning. Below the symbol was a blurred line of code that resonated faintly with the homologous STC code in Lin Yuan's system.

Lin Yuan kicked open the rusted door access system and dragged his brother into the radiation shelter. The moment they entered, the dark red liquid metal on the THRONE-01 wreckage suddenly surged. Instead of covering Lin Yuan, it lunged toward Lin Chen like a pack of hunting snakes, rapidly weaving into a cocoon-like structure around his body, completely enveloping him.

"No!" Lin Yuan reached out to grab him, but only felt cold metal.

The dark red cocoon emitted a steady, pulsating glow, perfectly synchronized with the flashing frequency of the 09-Ω pattern on Lin Chen's neck. Lin Yuan could feel that inside the cocoon, Lin Chen's vital signs had stabilized, and that intense neural pain was being largely shielded by some external field.

But Lin Yuan himself was excluded.

The wreckage of THRONE-01 lay on the ground, the machine spirit core within its chest cavity dimming as the "breathing" movements became extremely weak, as if it had exhausted all its energy. It had prioritized protecting Lin Chen, treating the organism marked as 09-Ω as a higher-priority target for protection.

Lin Yuan leaned against the heavy shielding door and slid to the floor. Promethium reserves were at 1.6%. The Silver-wire Network on his right hand continued to sting from the previous forced bridging, and the transparency of the White House in his vision jumped to 40%. The second hand of the bronze clock moved noticeably slower, with a ratio of about 1:0.7 to real time. He could indeed hear the physical echo of the pendulum resonating in this deathly silent pre-war laboratory.

Lin Chen's voice suddenly rang in his mind, not through his ears, but through the neural empathy link that had just upgraded to a shallow two-way connection.

"Brother, above."

Lin Yuan looked up. Through the observation window at the top of the shelter, he could see toward the vertical shaft. The Reaper Mother hadn't chased them down; instead, it hovered in the middle of the shaft, its six mechanical legs unfolded, releasing a large number of micro-drones. Like a swarm of bees, those drones dove toward all the exits in the upper levels of the abandoned city and began spraying quick-setting alloy.

The Mother was cutting off their retreat. It had activated the Hive Hunt Protocol, turning the lower abandoned city into a sealed, three-dimensional killing field.

Lin Yuan clenched his fists until his knuckles turned white. They were safe for now, but they were trapped. He looked at the dark red metal cocoon enveloping his brother and the completely silent wreckage of THRONE-01.

Lin Chen's hand reached out from a gap in the cocoon, his fingertips lightly touching the back of Lin Yuan's hand. Through the empathy link, Lin Yuan felt his brother transmitting more than just pain; there were also fragments of images—Lin Yuan's own tactical map memories were now flowing back into Lin Chen's consciousness.

At the moment their skin touched, the last drop of dark red liquid metal seeping from the THRONE-01 wreckage resonated visibly with the 09-Ω pattern on Lin Chen's neck, their frequencies matching and their light flashing in synchronization.

A connection older than the wasteland was confirmed at this moment.