I'm doing engineering in the instance.

The footprints are pointing downwards.

Instead of walking along the top of the dam, we climbed over the edge of the dam top and went down the downstream slope.

Xie Chengzhou shone his flashlight toward the gap in the guardrail. The guardrail was broken here; the rust at the break matched the surrounding area perfectly, indicating it was already there, not newly broken. The gap was wide enough for a person to squeeze through sideways. Footprints continued downwards from the gap, disappearing into the darkness of the dam surface, the steps even, without any signs of slipping.

He has walked this route many times.

"There's someone down there," Xie Chengzhou said. "Headl, crouching, about twenty meters away."

He swept his flashlight around the dam surface, the beam sweeping across the slope, over the cracks, over the moss, and finally settling on the faint light in the middle of the dam surface.

"Get out of here."

Old Zhao didn't ask why. He twisted the lid of the thermos—not tightened, but just checked to make sure it was loose—then turned sideways and went out through the gap, grabbing the remnant of the guardrail with his right hand, stepping onto the dam surface with his left foot first, pausing there for a second to feel the friction, and then started walking down.

His stride was small and his center of gravity was low, as if he had walked up this slope many times before.

Xie Chengzhou followed him out.

The surface of the concrete slope was rougher than he had anticipated—it was a rough surface with exposed aggregate, feeling like walking on coarse sandpaper. The anti-slip properties were better than he expected, but he had to avoid the areas covered in moss. The moss was wet, giving a soft, sinking feeling underfoot; he could feel a film of water forming between his shoes and the concrete, like walking on a thin layer of ice. He avoided the moss, stepping carefully down the rough surface with exposed aggregate.

The wind was blowing upwards, not across the dam, but up along the dam surface. I turned up the front of my work clothes, and it was damp with moisture, carrying a smell that I couldn't quite tell if it was the reservoir or the concrete. It was cold and wet, and it seeped into my collar and down my neck.

The numbness in my right ankle was more pronounced on the slope than on flat ground. Each time I stepped firmly, the force traveled from my ankle to my calf, causing a series of fine, stinging pains, like needles moving under the skin. It wasn't intense, but it was persistent—the kind of pain you could ignore but that wouldn't go away.

Then, on the ninth step, my right ankle buckled.

It wasn't a complete loss of control, but rather a feeling of suddenly not having enough force—like a bolt in the supporting structure that wasn't tightened properly. You wouldn't notice it normally, but it would loosen for a moment when it was under pressure on the slope. His right foot slid about ten centimeters to the side, the sole of his shoe making a short, sharp scraping sound on the exposed concrete. His left hand instinctively pressed down on the dam face, his palm directly against the concrete, the edges of the aggregate digging into his palm. At the same time, his right knee went down, his knee hitting the embankment with a dull thud, not heavy, but real.

He stopped there.

His heartbeat wasn't accelerating, but each beat was forceful, as if reminding him that he had almost missed. There was a mark on his palm, left by the sharp edge of the bone, not a cut, but a pressure mark, the edge still warm. There was also a warm spot on his right knee, from where he had been hit.

He pressed down on his right ankle to test it, and found he could exert force, then stood up.

Old Zhao glanced back at him but didn't say anything. Then he took two steps back, stood slightly lower to Xie Chengzhou's right, and extended his left hand, back of which was up, placing it under Xie Chengzhou's right arm—not to support him, but to cushion it, as if adding a temporary fulcrum to an unstable pipe. Only after Xie Chengzhou stood up and regained his balance did he withdraw his hand, turn around, and continue walking downstairs without saying a word.

Xie Chengzhou followed, bypassing the next patch of moss.

Li was at the very back, his left hand hanging limply, his right hand pressing against the slope surface for balance. His left ring and little fingers hadn't fully recovered. Xie Chengzhou didn't turn around, but he could hear Li's footsteps—slightly slower than Lao Zhao's, each step landing more cautiously, the rhythm of someone whose left hand wasn't entirely reliable walking on a slope.

They walked for about four minutes on a 20-meter slope.

They're getting closer.

Xie Chengzhou could see that person clearly now.

He crouched, his back to them, headlamp pointing downwards at a low angle, observing a detail on the dam surface, not looking at the distance. He held a notebook in his hand—a physical paper notebook, not a phone, not a tool for conscious manipulation, but a physical document in which he wrote with a pencil. The pencil traced across the page, then paused, tapping the edge of the notebook with the end of the pencil—a soft "tap"—as if confirming a number or considering what to write on the next line.

Xie Chengzhou shone his flashlight on him.

The beam of light fell on his back, but he didn't turn around. He simply tucked the notebook to his chest, obscuring its contents, then turned his head and glanced at Xie Chengzhou out of the corner of his headlamp.

He was in his early forties, with a square face, high cheekbones, and dark skin—not the kind from sun exposure, but the kind of dark skin that comes from years of working outdoors, exposed to the sun and wind. His skin was even and without sunspots. His work clothes were dark blue, a different style from Xie Chengzhou's, but still field work clothes. The cuffs were worn, and there was a slightly lighter-colored area on the elbow, a mark left from frequently kneeling or squatting while working.

Engineering boots, size 42 to 43, with the center of gravity shifted towards the forefoot.

it's him.

He didn't stand up, but simply adjusted the angle of his headlamp so that the light didn't shine directly on Xie Chengzhou's face, and then said, "You're the one who sealed that crack."

It's not a question.

"Yes," Xie Chengzhou said.

"Mortar sealing, quick-drying type." He paused, clipping the pencil between the cover and the first page of the notebook. "After sealing, the seepage agent retreated and moved upstream. Both left, the frequency decreased, and the rhythm changed."

"You saw it."

"I've been here for a while." He didn't say how long, but simply opened his notebook again, wrote a line on a certain page, and then said, "You've done something very important."

Xie Chengzhou did not respond to that sentence.

He was looking at the man's left wrist.

The cuffs were pressed down, pressed very firmly, so they couldn't be seen.

"How long have you been here?" Xie Chengzhou asked.

"Longer than you."

"This time? Or have you been here before?"

He turned to a page in the notebook, but didn't show it to Xie Chengzhou. He just glanced at it himself, then closed the notebook and said, "I've been here before."

Xie Chengzhou noted this detail down in his memo. The copy could be entered multiple times—he hadn't verified it, but this person's answer implied it was possible, or that he had some way to repeatedly enter the same scene. This detail itself was a piece of information, and important information at that.

"What's your name?"

You can call me whatever you want.

He wasn't looking at Xie Chengzhou when he said that; he was looking at the dam surface, at the spot where he had been squatting down to record—a crack, not wide, about two millimeters, running horizontally, perpendicular to the dam's axis, a location subjected to lateral tensile stress. His headlamp shone on that crack, as if he was still thinking about the line of text he hadn't finished writing.

Xie Chengzhou noted in his memo: "Third party, male, 40+, water conservancy engineering background, engineering boots 42-43, long-term slope walking, paper notebook, pencil, entered the same copy multiple times, number: covered, title: unknown."

Old Zhao squatted down next to Xie Chengzhou and shone his flashlight on the edge of the man's notebook. The notebook was already closed, but Old Zhao could see the cover—a blank kraft paper with no markings, held together by a rubber band. The rubber band was old and had fine cracks on its surface; it would break at the slightest touch.

I've been using this notebook for a very long time.

"You said part of this dam was designed in," Xie Chengzhou said. "What do you mean?"

The man then looked up, glanced at Xie Chengzhou, then at Engineer Li, and finally looked back at Xie Chengzhou, saying, "You're different from that geologist."

"What's different?"

"He wants to beat the game. You need to figure that out."

He paused. The wind blowing from the dam upwards flipped the hem of his dark blue work clothes up, but he didn't press it down, letting it flip. Then he pressed the notebook down on his knees, as if looking for a foothold to support the next sentence, before speaking:

"There is a rule in this dam, not in the explicit rules, but written in the structure."

"What rules?"

"Construction behavior influences the behavioral patterns of threatening entities," he said. "Destruction behavior, in turn, activates rather than retreats."

He paused, letting the words linger in the air for a second.

"I was verifying this rule, and you helped me verify which side to build today."

Xie Chengzhou remained silent.

It's not that I have nothing to say, it's that I need a second to put those words into action.

Build → Retreat. Destroy → Activate.

He pressed his foot firmly against the ground, feeling the coldness of the concrete seeping through his shoe, all the way to the lingering numbness in his right ankle. This wasn't random; it was a directional pattern. And this person said it was "written in the structure"—not a system rule text, not an explicit rule, but something embedded in the physical structure of the dam, the logic inherent in this particular scenario itself.

How did you know?

“I didn’t know when I first came,” he said. “The second time I came, I filled a crack with sand and gravel, and the seepage receded. I thought it was a coincidence.” He tapped the cover of his notebook lightly with the end of his pencil. “The third time I came, I changed the location, did the same thing, and got the same result.”

"You've come three times."

Four times.

He opened the notebook, found a certain page, turned it over, and handed it to Xie Chengzhou.

Xie Chengzhou took it and looked at it with a flashlight.

The densely packed numbers, timestamps, location coordinates, operation logs, and changes in seepage participant behavior—not qualitative descriptions, but quantitative ones, with frequency values, distance estimates, time intervals, and error annotations. This isn't a player's note-taking; it's an engineer's experimental record, the kind of data jotted down on the spot after a test. The handwriting is somewhat messy, but every number is written clearly.

The notebook was printed on ordinary graph paper, with slightly curled edges. Several pages were wet, causing the writing to become blurred, but the numbers were still legible.

Xie Chengzhou flipped through the notebook, turned to the record of the third experiment, stopped on that page, and looked at it for about twenty seconds.

"Your major."

"Water conservancy," he paused, "I've been doing it for twelve years."

Li, standing next to Xie Chengzhou, glanced down at the notebook, then looked up at the man and said, "Part of this dam was designed in—are you referring to the crack, or this rule?"

The man glanced at Engineer Li. This was the first time he had looked at Engineer Li seriously; it wasn't just a quick glance, but a pause, as if he were reassessing Engineer Li as a person.

Then he said, "Yes, they are."

"Even cracks?"

"The crack was deliberately created, but the location was intentional," he said. "It wasn't chosen randomly; it was chosen according to this rule—to create it at the node most easily triggered by construction activities, making repairs more difficult." He paused, "You almost disturbed that crack in the corridor today."

Xie Chengzhou handed the notebook back to him.

"Feng Bo," Xie Chengzhou said, "was he someone you arranged?"

“No,” he said. “He came on his own, and he has his own judgment.” He took the notebook, closed it, and wrapped the rubber band around it twice, moving very slowly, as if giving himself time to think through his next sentence. “But his judgment happens to be in the interests of certain people.”

"Who is it?"

He did not answer the question.

He put the notebook into the inside pocket of his work clothes, pressed it down to make sure it was secure, and then said:

"Part of this dam was designed in."

He repeated it, but his tone was different from the first time. It wasn't a statement, but a conclusion. It was the last sentence that remained after the man had squatted on the dam four times and filled a notebook.

"I'm referring to this rule. Someone wrote it into this copy."

He paused for a moment.

The wind was still blowing on the dam, carrying moisture and that fishy smell.

"Not constitutive."

The way these four characters land is different from the previous ones.

Xie Chengzhou pressed his foot firmly on the ground, the coldness of the concrete seeping through his shoes to his ankle, and into the lingering numbness. He didn't speak immediately, nor did he jot anything down in his notes. He simply stood there, letting those four words linger in his mind for a second.

It is not an constitutive model.

This means that someone wrote a rule—a rule that the constitutive didn't write or didn't know about—outside or within the constitutive framework. This implies that this copy is not just a scenario generated by the constitutive; someone added something to it, added logic, added a rule for "construction behavior," making it part of this copy.

Xie Chengzhou felt the soles of his feet.

The vibration has changed.

It wasn't the frequency that changed, it was the weight that changed—it was as if something in the distance stood up and put its feet on the ground. The entire dam body slightly transmitted that weight at that moment, from the soles of the feet up to the knees, to the waist, and then it dissipated, but that moment was real.

"It's here," Old Zhao said.

That person has already stood up.

He wasn't going uphill to retreat to the top of the dam; he was going downhill to a lower part of the dam. His steps were quick but not flustered. It was the rhythm of someone who had walked this path many times. Every step he took was steady, with his toes touching the ground first and his center of gravity slowly shifting backward. It was the kind of gait that only someone who had walked on slopes for a long time could have.

"It won't go below this height," he said, taking a few steps, stopping, and not turning back. His voice drifted upwards. "The water pressure isn't enough. It needs sufficient water pressure to maintain its shape. The water pressure is low at the lower part of the dam, so it won't come down."

Then he continued walking down.

Xie Chengzhou mentally checked the information—the seepage agent's range of movement was related to water pressure, something he hadn't verified himself, but this person had verified it four times, and the data was in that notebook. This was a new fragment of a rule, not in the explicit rules, but derived from experiments.

"Go down," Xie Chengzhou said, "follow his route."

Old Zhao was already moving. He unscrewed the lid of his thermos halfway, ready to throw it in at any time, and then started walking downhill. His stride was the same as that person's, with his toes touching the ground first and his weight shifting back down – an instinct honed from thirty years as a plumber on various slopes.

The three of them walked down the dam. Xie Chengzhou was in the middle, Lao Zhao was in front, and Engineer Li was behind. They shone their flashlights under their feet, avoiding the moss and stepping on the rough surface of the exposed aggregate, descending step by step.

The tremors intensified behind them.

It wasn't the vibration under his feet, but the vibration of the entire dam, emanating from the concrete of the dam surface, from the soles of his shoes to his feet, to his legs, like a low hum emanating from the dam itself under some kind of pressure. It wasn't a sound, but a vibration, a frequency you couldn't hear but could feel. Xie Chengzhou didn't turn around. He knew he wouldn't see anything if he did. The large entity wasn't on the dam surface; it was inside the dam, in the water, in some place he couldn't perceive.

He put his foot firmly on the ground and continued walking down.

At the lower part of the dam face, at the end of the slope protection is a drainage ditch. Behind the drainage ditch is a gravel area, and beyond the gravel area is a flat area with several structures on the flat area—a monitoring station, a drainage pump house, and management buildings, which are auxiliary facilities of the dam area.

The person was standing in the gravel area, with their back to them, looking in the direction of the management office.

Xie Chengzhou walked over, stood next to him, and followed his gaze.

There was light coming from the window of the management office. It wasn't a flashlight, but a fixed lamp, a warm yellow, like an incandescent bulb, shining through the window cracks and falling on the gravel at the doorway, illuminating a small patch of ground.

"There's electricity here," Xie Chengzhou said.

"There's a lot here," the man said. "You didn't look at this area carefully before you came in."

"You saw it."

"The first time I came, I walked through the entire dam area," he said, "It took me about two hours." He didn't turn his head; his eyes remained fixed on the window. "How much time do you have left today?"

Xie Chengzhou glanced at the numbers on his wrist.

Water level: 5.71 meters. Distance from warning line: 2.29 meters.

"It depends on the rate of increase," Xie Chengzhou said. "If it maintains the current level, it'll take about two hundred minutes. If the rate of increase accelerates—"

"It will speed up," the man said. "The rate of increase will accelerate as we approach the warning line; this is a pattern in this instance, and I've observed it three times." He paused for a moment. "About forty minutes before we approach the warning line, the rate of increase will double."

Xie Chengzhou noted this number down in his memo.

"What's in the management office?"

"We have more and better repair materials than we do in the maintenance room," he said. "We have templates, waterstops, expansion bolts, and a small manual grouting machine." He paused for a moment. "The mortar in the maintenance room isn't enough to repair the main crack."

Old Zhao, standing nearby, said, "How did he know we were going to repair the crack in the main shaft?"

"Because you are engineers," the man said, "when engineers see a crack, their first reaction is to fix it."

Old Zhao twirled the thermos in his hand, but didn't reply.

Xie Chengzhou asked, "You've been inside?"

"I've been inside, the materials are genuine and usable." He paused, then said, "But there's a problem inside that you need to know before you go in."

"explain."

"The door lock is a mechanical lock, the key is inside, but the door is ajar and can be pushed open directly." His tone was calm, as if he were explaining the entry conditions for a construction site. "The problem isn't the door, it's that something is waiting inside."

"The Infiltrators".

"Not a seepage agent." He paused. "It's another kind. I don't have a name for it. Go in and see for yourselves."

Xie Chengzhou went through the information and then said, "Aren't you going in?"

"My work is outside," he said. "Your work is inside."

He adjusted the angle of his headlamp and walked deeper into the gravel area. After a few steps, he stopped, turned his back to them without looking back, and said:

"Construction changes the rules; this is the most important hidden rule in this instance. You have already verified it."

He paused for a moment.

"But you haven't figured out to what extent it can change things."

Then he left.

The light from the headlamp grew smaller and smaller in the darkness of the gravel area, and finally disappeared.

Xie Chengzhou stood in the gravel area, looking at the lit window, for about a minute.

The vibrations behind him gradually weakened and subsided. The large entity either stopped or turned away, retreating to a more distant location. The sensation under his feet changed from "something standing there" back to "something waiting in the distance." The two sensations were different, and Xie Chengzhou could distinguish them.

Old Zhao stood beside him without saying a word, and used his flashlight to scan the management room—doors, windows, roof, and the ground at the entrance. He conducted a basic survey before entering the site, a habit honed from thirty years of construction site experience. He did it naturally without thinking.

Mr. Li slowly bent his left ring finger down to the bottom, and then straightened it out.

"I'm all better," he said. "Completely recovered."

Xie Chengzhou nodded.

He opened the memo.

Find the entry for "Construction Behavior - First Validation" and add the following paragraph below it:

"Construction behavior, formal confirmation, mechanism: Construction → Infiltrators retreat; Destruction → Infiltrators activate. Directional pattern, not random, not accidental. Data source: Third party, four experiments, quantitative records, paper notebooks. Rule nature: Implicit rules of copying, not explicit rules of constitutives, not system-generated—someone wrote it in, not constitutive."

He paused after “not an essentialist”.

He knew the meaning of those four words, but knowing and understanding are two different things. He only knew them now; he hadn't figured them out yet. He added parentheses after that line: "(Meaning: To be expanded)" and continued writing:

"Unresolved issues: ① Who wrote it in, and why; ② Feng Bo's judgment 'just happens to align with the interests of certain people'—who are they, and what are their interests; ③ The third party's purpose, identity, and how much they know."

He paused below these three points, then started a new line in his memo and wrote a question:

"If the act of building can change the rules of this copy, then what can a systematic act of building—planned, logically designed, and targeted—change?"

He paused for a long time after that line of text.

In every project he'd worked on before, there was a core question before construction began: How much load can this structure bear? Load isn't just weight; it's all the forces applied to the structure—live loads, dead loads, wind loads, seismic loads, temperature loads. An engineer's job, in a sense, is to calculate the loads and then design the structure to support them.

But what if the load could be applied actively?

If the act of building itself is a load, applied to the copy rules and altering the "load state" of the rules, then—

He cut off that line of thought.

Too fast. There's not enough data, not enough inferences; this direction needs more validation, not now.

He wrote one word after that line of questions: "Waiting".

Then close the memo.

"Go in," he said, "and see what's waiting inside."

Old Zhao was already walking towards the management office, his steps steady, his flashlight shining on the doorway, and his other hand unscrewing the lid of his thermos halfway open.

Xie Chengzhou followed.

After walking a few steps, I felt the vibration under my feet.

The amplitude has decreased to 0.1 Hz; the larger entity has retreated, upstream, back to where it was. But it's still there. Xie Chengzhou mentally matched this detail with what the third party had said—"The water pressure isn't enough; it needs sufficient water pressure to maintain its shape." So, when the water level reaches a certain height, when the water pressure reaches a certain critical value, it can maintain a larger shape, reach a higher position, and—

He cut off this inference, marked it "to be verified," and then turned his attention back to the door of the management office.

The door was ajar, with a gap of about two centimeters. Light shone through the gap and fell on the gravel at the doorway, a warm yellow, incandescent light.

Old Zhao placed his hand on the door frame, but didn't push it open. He listened intently.

Quiet.

There was no sound inside.

Old Zhao glanced at Xie Chengzhou.

Xie Chengzhou nodded.

Old Zhao pushed the door open.

The light shone out, illuminating a small patch of ground in the gravel area and the faces of the three people. The warm yellow light seemed out of place in the gray dam, as if it were leaking from somewhere else.

The things inside saw them.

Xie Chengzhou stopped at the door, glanced around at the situation inside, and then wrote the last line in his memo:

"Management room; repair materials; confirmed; other threatening entity; type: unknown; third party claims 'another'; different from the seepage entity."

Then he stepped inside.