The two left the filtration plant, following the old cement road leading back to the inn as the sun tilted toward the west. The way back was familiar, but for some reason, Thuong Sinh's footsteps were slower than usual.
It wasn't because of fatigue, but because he felt a very familiar sensation appearing.
The feeling of being watched.
It wasn't clear, nor was it direct; it was like something standing just outside his range of perception—far enough to not be considered tracking, but not at all random.
Lam Thanh Moc, seeing Thuong Sinh slow down, gradually realized the problem. She did not turn her head, only asking very softly: "Is someone watching?"
"Yes," Thuong Sinh replied concisely.
The two continued walking, neither changing their speed nor their route. In the apocalypse, the one who changes direction first is usually the weaker one.
As they turned through a narrow alley, the light suddenly darkened. In that moment, Thuong Sinh felt it more clearly.
Not one person. At least two.
One stood high, with a stable aura, like an observer; the other was lower, with very light footsteps that would be mistaken for the wind if one didn't pay close attention.
There was no killing intent, only evaluation.
Thuong Sinh frowned slightly.
Azure Line Alliance.
He didn't need evidence; his feeling was enough. This method of observation wasn't like a predator, but like a chronicler—simply looking, remembering, and then withdrawing.
Upon exiting the alley, the sensation faded, as if it had never existed.
Lam Thanh Moc finally let out a soft breath.
"They didn't act."
"No," Thuong Sinh nodded. "They were only watching." "It seems I have been put on a list."
Lam Thanh Moc glanced at him.
"You don't like it?"
"No," Thuong Sinh gave a thin smile. "It's just a nuisance."
The two continued walking as the lights of Luc Thuy gradually appeared ahead. The crowd was sparse, voices mingled in the evening wind; everything looked as normal as any other day.
But from today onward, there were eyes that would no longer leave him. In a place higher and further away, a figure closed a notebook and turned to leave.
The following days passed quite normally.
In the mornings, Thuong Sinh and Lam Thanh Moc went to the old filtration plant, flipped through the mission board, and occasionally ran into Lam Vu and Trinh Tuan. The two women always looked at each other with eyes that disliked the other, choosing targets within their capability that weren't too ordinary. At noon they left the safe zone, and in the evening they returned to turn in missions and exchange for supplies.
No showing off, no drawing attention. But even so, there were eyes silently memorizing him.
That day, the mission led them to the edge of an old residential area, which had been a student dormitory before the apocalypse struck. The buildings were low, the paths narrow, and the walls were mottled with black scorch marks and zombie claw marks.
Just as they finished handling a group of the living dead scattered in a parking lot, another team appeared from the head of the opposite street.
Not many. Six people.
Equipped more neatly than ordinary people, with a reasonably spaced formation; their eyes were always scanning horizontally and vertically as they moved.
Azure Line Alliance.
No one needed to introduce them; looking at their aura was enough. Both sides slowed down at almost the same time. No greetings, no questions; just two groups of strangers accidentally crossing paths in a mission zone.
Lam Thanh Moc glanced over the opponents once, her gaze sweeping past and then retracting very quickly.
Thuong Sinh did the same, until he grazed past the person at the very rear. His gaze stopped on the person at the end of the opponent's formation—thinner than before, but a single glance was enough.
Chu Minh.
Thuong Sinh remembered very clearly—not because of hate, but because that was the first time he realized: humans in the apocalypse are more dangerous than zombies.
Thuong Sinh retracted his gaze, his expression unchanging, as if merely passing a stranger.
Chu Minh also flicked a glance toward him, then immediately moved it away—not recognizing him, or more accurately, not being sure.
Thuong Sinh's appearance was now too different compared to when he was at the school: his gaze was heavier, the aura around him was thicker, a faint scar stretched across his left eye, and his hairstyle had changed.
He no longer had the appearance of the ordinary student he was then.
Thus, both groups passed each other. After a while, the leader of the Azure Line Alliance gave a slight signal, and their formation changed direction, avoiding the area that had just been cleared.
Lam Thanh Moc, walking beside him, noticed Thuong Sinh looked at the last guy longer than the others. She tilted her head slightly, asking very softly: "An acquaintance?"
"No," Thuong Sinh replied immediately.
That wasn't entirely a lie.
Chu Minh wasn't the person he was looking for, wasn't the decision-maker at that time, and wasn't the debt he needed to collect. He was just a name that had once appeared on the road he traveled.
The two groups separated, each side continuing their own mission without looking back.
But in the final moment before turning into two different streets, Chu Minh instinctively turned back to look one more time.
There was something about that back that made his spine go cold.
In the following days, news of a new poisonous area began to spread through the underground trade routes.
At first, it was just whispers.
A medium-sized Black faction organization sent three people in to scout the path. Two days later, only one returned—surviving, but with ash-gray flesh and breath heavy with a metallic stench. Before he could give a full report, he coughed up blood right at the base gate; the poison had invaded his organs, and he could not be saved.
Another power was more cautious, equipping full filter masks, anti-toxin medicine, and even bringing a healing-type Ability user. This time more people returned, but none were whole. Some lost their sense of smell permanently, some were paralyzed in the lower half of their bodies, and some, though they kept their lives, found their Ability became unstable, causing nerve-shredding pain every time they used it.
The news was suppressed, but the consequences could not be hidden. In just three days, the three largest organizations in Luc Thuy all had to order a halt to approaching that area.
Finally, that sector was marked with a new symbol on the mission map: RED LEVEL DANGER ZONE (Long-term toxic gas accumulation, unsuitable for prolonged combat).
Accompanying it were a series of bounty missions. The rewards were very high, but no one accepted them.
That day, at the old filtration plant mission transit point, Thuong Sinh and Lam Thanh Moc stood at the edge, before the mission board.
"Heard about that sector yet?"
"The red poison zone? You'd have to be crazy to enter."
"Some people came out alive, but they'd be better off dead."
"True, even if cured, they're crippled for half a lifetime." Someone scoffed: "The reward is high because they don't expect anyone to return alive."
Lam Thanh Moc frowned out of reflex. She glanced over the area map displayed on the blue board covered in red mission papers and eye-searing red warning symbols.
"This kind of accumulated poison..." she lowered her voice. "Isn't something an Ability user should touch."
Thuong Sinh said nothing, his gaze lingering on a mission paper for a long time.
The mission they accepted today was unrelated to the red zone.
It was just an external residential area: confirming the mutation status, collecting samples, and clearing out a few wandering targets. Familiar work, not difficult, and not worth being tense over.
Until the wind changed direction.
Initially, it was just a very faint smell—lightly metallic, like damp metal mixed with the scent of mud. Lam Thanh Moc stopped first, frowning out of reflex.
"Do you smell that?"
Thuong Sinh didn't stop either—not because of the smell, but because of a sensation. The surrounding air seemed a bit heavier, cold and sticky; inhaling it into his lungs brought a slight numbing sensation to his throat.
He raised his head to look into the distance.
At the end of the ruined street, among the crooked buildings, a thin mist of deep gray was spreading—slowly but without stopping, as if something were breathing.
"This isn't right..." Lam Thanh Moc whispered.
Before she could say more, a dry shredding sound suddenly rang out from behind.
Lam Thanh Moc turned her head.
The road they had just traveled through had been swallowed by the gray mist. It wasn't immediately dense, but a single glance was enough to understand: they couldn't go back.
Thuong Sinh also looked around now; he sensed it much more clearly than Lam Thanh Moc. The air was not just heavy, but slowing down.
He frowned slightly; it wasn't an eruption of poison, it was poison accumulating and spreading, with a center and a trajectory.
"It's spreading faster than predicted," he said, his voice deep, carrying no panic.
Lam Thanh Moc immediately understood, her eyes darting through possible retreat directions, but the more she looked, the more worried her expression became. In front, the gray fog had crawled onto the steps of the residential area. To the left, the headwind carried a stronger metallic smell. To the right, the cracks in the ground had begun to emit faint smoke.
No direction was clean.
"We're pinned."
Thuong Sinh didn't reply. He took a step forward, standing slightly ahead of Lam Thanh Moc, his gaze locked onto the advancing fog. In that moment, he had finished his calculations. If they didn't retreat in time, she couldn't withstand the amount of poison inhaled if they ran, and if they waited, the poison would thicken by the minute.
There was only one choice: to render the encirclement useless.
Thuong Sinh took a deeper breath than usual.
Lam Thanh Moc was startled immediately: "You—"
"Don't breathe," he said quickly, not turning his head. "Keep your breathing light, don't circulate your Ability."
Lam Thanh Moc froze, looking at him.
Thuong Sinh lightly closed his eyelids. Inside his body, the "Vile Blood Heart-Corroding Art" quietly circulated—this time, it wasn't for blood essence or external objects. It was for the poison saturating everywhere.
The blue lines quietly turned black, rising in a tangled mess all over his body; his eyes also turned red.
The ice-cold air rushed into his lungs like needles piercing his meridians, painful to the point of numbness. But the toxic gas, upon entering, was diverted by a violent pulling force, forced to aggregate, and crushed bit by bit.
Not fully refined, but it couldn't be allowed to spread out.
Lam Thanh Moc, from behind, only saw the gray currents in front being rapidly inhaled by Thuong Sinh, bit by bit, by some force.
"Follow me." Thuong Sinh opened his eyes now, stepping forward, neither fast nor slow.
Lam Thanh Moc said nothing, but she understood. Looking at those black veins, she knew he was using that state again. She gritted her teeth in worry, following him closely.
With every step Thuong Sinh took, the ground beneath his feet cracked slightly.
It wasn't corrosion, but the toxic gas being pressed down, losing its grip, and forced to disperse. His breathing remained steady, but inside, it was entirely the opposite.
The "Vile Blood Heart-Corroding Art" was not circulating according to its familiar cycle. Blood vessels were forcibly widened, and the toxic gas was gathered like black mud, driven into a single point and then crushed, forced to dissipate into raw energy.
Every heartbeat carried a stinging pain, as if something were clawing from the inside. His skin grew gradually cold, and the black lines beneath his skin became clearer, spreading up his neck, reaching near his jaw.
Lam Thanh Moc saw it all. She didn't speak, didn't pull him back, and didn't ask "can you endure this?"
Because she knew if he had stepped this far, there was no way back.
The surrounding gray mist continued to roll, but the speed of its spread had slowed significantly. Not because it grew weaker, but because the center point was being drained.
Thuong Sinh stopped. He tilted his head, his deep crimson eyes glancing toward a ruined building on the right.
"Through there."
Lam Thanh Moc immediately changed direction without hesitation.
Just as they left the main street, a shredding sound rang out behind them, as if something inside the poisonous fog had collapsed. A dense patch of fog gathered and then suddenly flared up, but it only touched the empty space they had just vacated.
A few seconds late.
If they had been a few seconds slower, the consequences wouldn't even need thinking about.
Thuong Sinh placed his hand on the ice-cold wall, his body shivering once very lightly—only once—before he continued walking.
Finally, when they passed the edge of the most heavily contaminated area, the air suddenly thinned. The metallic smell faded, and the numbing sensation in his throat vanished.
The black lines on his body slowly receded, but they didn't disappear immediately, remaining hidden under the skin like traces that hadn't faded. The red in his eyes also paled, leaving only a deep exhaustion. He let out a long breath.
Only then did Lam Thanh Moc step forward half a pace, standing at his shoulder. She didn't touch him, just looked for a very long time.
"Are you alright?" she spoke softly, her voice a bit hoarse.
Thuong Sinh looked at her; his eyes were watering, and he didn't dare look back directly.
"I'm fine... just a bit tired." His voice was calm as if nothing had happened.
Lam Thanh Moc didn't believe him—not because his voice shook, but because he was too calm. She saw very clearly that his shoulders were still tense; his breathing had stabilized, but each inhale was deeper than normal.
She stepped up, intending to support him.
"Don't touch me."
Lam Thanh Moc froze, her hand hovering in mid-air trembling before slowly withdrawing. She understood—the toxic gas he had forcibly swallowed couldn't dissipate instantly; it was still lingering in his flesh and blood. If she touched him, that toxin would immediately transfer to her through the skin.
He didn't want her to be hurt. But that absolute protection felt like a knife cutting into her self-esteem.
"Find a place... to rest first," Thuong Sinh said, his voice gravelly.
They found a basement of an old townhouse; the iron door was rusted but still sturdy enough. Thuong Sinh stumbled into the darkest corner, sitting flat on the cold concrete floor, back leaning against the peeling wall. He placed his sword beside him, hands hanging limp over his knees.
Lam Thanh Moc stood at the basement entrance looking in. Under the dim light, she saw the black veins on his neck had not receded but began to twitch, spreading out like eerie tree roots. Black sweat flowed down, pungent and acrid, running from his temple to his jaw. He was shaking—a tremor from deep within the marrow that no amount of iron will could hide.
She couldn't stand it anymore. She stepped forward, kneeling down opposite him, at a distance just far enough to not touch but close enough to hear his teeth gritting together.
"Are you going to keep doing this forever?" Her voice shook, half in anger, half in pleading. "Every time something happens, you push me behind. Thuong Sinh, I am not a vase for you to display; I am your companion!"
Thuong Sinh opened his eyes slightly, the deep crimson pupils not having fully retracted, looking at her with exhaustion: "If I didn't do it... you would die. This poison... your Ability cannot filter it."
"Then let me hurt with you!" Lam Thanh Moc shouted, tears finally spilling over. "Watching you destroy yourself for me—that feeling is more terrifying than death! This way you protect me is what's turning me into a truly useless person."
Thuong Sinh was silent. He watched her tears fall onto the dust-covered floor. The blood essence in his body was roaring, demanding release, demanding blood and slaughter to dissipate the toxin.
"You don't understand..." he whispered, his breath carrying faint gray smoke. "My method... was always a dead-end road. I am only utilizing my own death to prolong your life."
Lam Thanh Moc was stunned. For the first time, he admitted the cruel truth about the method he practiced. She didn't retreat; on the contrary, she reached out. Emerald vines slowly crawled from her palms, but this time they carried no sharp thorns. They gently wrapped around Thuong Sinh's blackened hands, creating a lush green barrier.
"If it is a dead-end road, then I will plant flowers on that road for you to walk on."
She pressed her palm through the protective layer of vines onto his ice-cold back of the hand. Her plant-type Ability began to emit a gentle green glow, trying to neutralize the "fire poison" rising from his flesh.
Thuong Sinh shivered slightly. The cooling sensation transmitted from Lam Thanh Moc didn't make the toxin disappear, but it made his "rotting" heart beat for one second of peace.
Outside, the gray mist still shrouded the dead city. Inside the dark basement, two shadows leaned on each other—one deep black and full of sin, one bright green and full of hope, flickering amidst the apocalypse.