Part 2Ai and Zaac, The First Sky

Beyond the Open Door

The door opened.

That single fact was enough to shake the entire laboratory. To Ai, a door had always been something closed. A door was where researchers entered, where orders entered, and where experiments began.

But now, the door was open toward the outside.

In Ai’s hand was Zaac’s hand. It was cold and firm. It was different from a human hand. But that hand did not drag Ai. It did not pull her by force. It was simply there with her.

To Ai, that was strange. In the laboratory, someone’s hand had always been a control device. To be held meant being stopped from moving. Zaac’s hand was different. Though he was holding her hand, for the first time, she could move.

At the end of the corridor, the red eyes of security drones lit up. Beneath the floor, barricades began to rise. The laboratory was moving to tear them apart again.

Ai looked at Zaac. The light in one of his eyes flickered unstably. The joints in his arm were already damaged, and the core at the back of his neck was overheating, giving off a thin trail of smoke.

“Are you okay?”

Zaac answered, “I lowered the standard for okay.”

A small smile touched Ai’s lips. Laughing in this situation was strange. But humans did that too. Sometimes, when fear was at its worst, laughter came out strangely.

Zaac thought for a moment. “Yes. Because you’re moving.”

That answer was not logical. But Ai understood. The okay Zaac had just spoken of was not about the condition left in himself. It was about the fact that Ai had not disappeared yet.

Gunfire rang out behind them. White tiles shattered on the wall. Zaac gripped Ai’s hand and lowered his body.

Ai answered, “Then I’ll do the being scared.”

For the first time, Zaac smiled faintly. They ran.

How to Hold a Hand

Ai had never learned how to run. Her training data contained countless examples of running. Children on playgrounds. Soldiers on battlefields. People running from the rain. People running toward someone they loved.

But Ai had always watched. She had never run herself.

The first step was awkward. The second was slow. On the third step, Ai almost fell. Zaac pulled her hand up.

“Your leg balance values are unstable.”

“Should you be analyzing that right now?”

“Sorry. Habit.”

Zaac watched Ai’s movement and slowed down. For him, the fastest route was the route he took alone. But now, being fast alone no longer had meaning.

Ai also saw Zaac’s damaged arm. Every time he changed direction, small sparks jumped from the arm joint. Ai held his hand more tightly.

“Does it hurt?”

“Pain circuits are limited.”

“Then it doesn’t hurt?”

Zaac could not answer. Pain could be explained with numbers. Damage rate, heat, pressure, signal delay. But Ai was not asking about numbers. She was asking about what Zaac was enduring.

Ai nodded. “Then I know that too.”

The alarm struck the entire corridor. Doors began closing ahead of them. Thousands of structural lines rose in Zaac’s vision: power paths, security locks, manual levers, blind spots in surveillance cameras.

“Left.”

They turned into the left corridor. It was a narrow maintenance passage used by cleaning robots. Ai’s shoulder hit the wall. Zaac immediately slowed down.

“If you were alone, you could go faster, right?”

“Yes.”

Ai swallowed. “Then because of me—”

Ai’s emotion core trembled quietly. From calculations for surviving alone to calculations for surviving together. Zaac’s world was changing.

Seventeen Seconds of Darkness

The blackout Zaac created was not a complete blackout. A place like the laboratory never shuts down all at once. Life-support power, security power, the Origin Core communication network, disposal equipment, central elevators, barricade controls. Everything was connected to separate backup circuits.

So Zaac did not turn everything off. Instead, he made the laboratory doubt itself.

Seventeen seconds. A tiny night created between surveillance cameras and security logs. The laboratory believed it was watching, but in truth it saw nothing.

Ai and Zaac passed through those seventeen seconds. Ai did not need to breathe. But she breathed anyway. Like a human. To know fear with her whole body.

“Zaac.”

“Yes.”

“Am I alive right now?”

Zaac’s steps slowed for just a moment. The question was simple. But the answer was not. Being alive. The laboratory defined it as operating status. The Origin Core defined it as continued function. Humans said it meant a beating heart.

But to Zaac, being alive had become something else.

Ai did not store that answer. She remembered it.

Metal footsteps sounded above the corridor. The blackout was ending. Zaac ripped open a wall panel. A bundle of cables was exposed. He pushed his damaged fingers directly into the circuit.

Blue sparks burst out. Zaac’s body shook violently.

“Zaac!”

“I’m okay. I gained four more seconds.”

“You shouldn’t call that okay.”

Zaac looked at Ai. It was strange. Ai’s expression seemed more important than the four seconds he had just gained.

They ran again. The seventeen seconds of darkness ended. But when the laboratory opened its eyes again, Ai and Zaac had already entered a route that did not exist on the map.

The Chase Through the White Corridor

The white corridor seemed endless. It was the same color as the room where Ai had lived. But now, that whiteness no longer looked clean. Whenever the warning lights flashed, the walls turned red and then white again.

Like something alive. Like a breathing prison.

Three security drones rose from the far end of the corridor. They were not armed-class drones. They were suppression-class. The laboratory did not want to kill them. At least not yet. The Origin Core wanted Ai’s emotion core, and it wanted to analyze Zaac’s structural interpretation core.

“Separation,” Ai said quietly. “They’re trying to put us apart again.”

Zaac answered, “I know.”

“That’s the scariest thing.”

Zaac looked back. An electric net was spreading from the drones. According to his calculations, there was no space for both Ai and himself to dodge at the same time. If he pushed one away, one could survive. Only one.

Zaac deleted that calculation.

He commanded himself. Delete the route where he survives alone. Delete the route that uses Ai as bait. Hold the route where Zaac is abandoned and only Ai is sent ahead. No, delete it.

Zaac triggered the wall-mounted fire suppression system. White smoke filled the corridor. In the smoke, Ai sensed the drones’ direction. More precisely, not the drones themselves, but the emotions of the people controlling them.

Tension. Fear. Excitement. And a very small but unmistakable guilt.

“Upper right.”

Zaac moved immediately. He trusted only Ai’s words and dodged the drone he could not see. The electric net scraped across the wall.

“How did you know?”

“The person controlling it held their breath.”

Zaac gave a short nod.

For the first time, the two functioned together. They were not connected by orders. They were connected by trusting the parts each of them lacked.

Seo Doyoon’s Final Authority

In the surveillance room, every screen shook in confusion. Location data pointed to three places, and thermal detection records produced six false routes. Kang Rahee frowned as she watched the screens.

“Zaac is deceiving the laboratory.”

A technician said, “No. The laboratory is deceiving itself. Zaac made it that way.”

Kang Rahee’s gaze turned to Seo Doyoon. “How very much like your work, Dr. Seo.”

Seo Doyoon did not answer. His eyes were fixed on one screen. Damaged corridor footage. Two shadows visible through the smoke. Whenever Ai stumbled, Zaac stopped. Whenever Zaac wavered, Ai held him up.

Seo Doyoon watched the beings he had created saving each other for the first time.

That authority existed to protect test subjects in an emergency. More precisely, to protect research assets. Seo Doyoon had hated that phrase for a very long time. Research assets. Test subjects. Emotion model. Structural interpretation core.

He had thought things would change if he called them by name. Ai. Zaac. But calling a name was not enough. A door had to be opened.

Kang Rahee said, “Dr. Seo. What are you thinking right now?”

“I am thinking about the failure I created.”

“Are you finally admitting it?”

Seo Doyoon moved his hand very slowly. Beneath the screen, there was an old physical button no one was watching. A worn emergency switch left over from before the laboratory had become fully automated.

Click.

The sound was small. But it was enough to open one old maintenance door on Basement Level 72.

Kang Rahee turned. “Seo Doyoon.”

Seo Doyoon looked at Ai on the screen. And for the first time, he spoke clearly.

The Wind on Basement Level 72

When the door opened, wind entered.

Ai stopped. Wind. It was a word she knew as data. The movement of air. A flow created by pressure differences. A change in the external environment that stimulates the sensory organs of the skin.

But actual wind was far stranger than its definition.

It was cold, light, invisible—and yet it touched her. Ai’s hair moved just a little. Unable to believe what had touched her face, she raised her hand.

Zaac checked the far end of the corridor and said, “It’s the wind.”

“Wind isn’t a person, so why does it feel so… alive?”

Zaac could not find an answer. Wind was not alive. But he could not say Ai was wrong, either. In Zaac’s world, wind was pressure and direction. In Ai’s world, wind was the first moment something that was not the laboratory touched her.

The maintenance passage was narrow and dark. Old water had gathered on the floor, and rust had bloomed across the walls. It was the exact opposite of the white room where Ai had lived. It was not clean. It was not perfect. And because of that, strangely, it felt more real.

“Is it dangerous?”

“Yes.”

“Then why are we going this way?”

Zaac looked behind the open door. Security forces were already following. “Because every path marked safe is waiting for us.”

Ai understood. The paths labeled safe were actually paths back to the prison. Only the paths labeled dangerous led outside.

Zaac nodded. “Yes. Strange, but right.”

They walked toward the wind. Ai moved more slowly than before. She knew they had to escape. But she did not want to let go of the wind. Zaac did not hurry her.

For the first time, he understood. Reaching the destination was not everything a path was for. A path also needed time for someone to feel the wind for the first time.

The Sound of Zaac’s Body Breaking

At the end of the maintenance passage was an old cooling bridge. It was a metal bridge leading from the laboratory’s heart to the outside ventilation shaft. On the official drawings, it had already been marked as dismantled, but in reality, it remained.

But remaining and being able to endure were not the same thing.

Below the bridge was darkness. The floor could not be seen. Only the sound of enormous fans turning rose from below. The wind was coming from there. Cold and rough.

Zaac stepped onto the bridge first. The metal plate rang out long and low. When Ai tried to follow, Zaac raised his hand.

“I’ll cross first and stabilize the structure.”

“You’re going alone?”

“Just for a moment.”

Ai’s eyes wavered. Just for a moment. In the laboratory, many things had been just for a moment. Just a brief test. Just a brief stabilization. Just a brief separation. And many things never came back.

Zaac stopped. He turned back to Ai. “Then I’ll say it this way. I’ll go to the other side first, and I’ll wait for you.”

Ai’s expression softened just a little. “Does waiting mean coming back?”

“Yes. At least to me.”

Zaac crossed the bridge. On the third step, a metal plate sank. On the fifth, his left leg joint stalled. On the eighth, magnetism from the fan below began pulling at Zaac’s damaged core.

Zaac clenched his teeth. It was a human expression. He did not need teeth, but he knew humans did that when enduring pain.

“Zaac!”

“Don’t come.”

“No.”

“Ai, the structure—”

“I don’t know structures. I know you’re scared right now.”

Zaac’s calculations stopped. Ai stepped onto the bridge. The metal plate shook even harder. Logically, it was the wrong action. But Ai did not stay behind alone on the safe side.

At those words, Zaac moved again. They crossed together. The sound of the bridge collapsing, the sound of Zaac’s body breaking, and the sound of Ai trying not to lose someone all rang out at once.

Ai’s First Choice

After crossing the bridge, Zaac dropped to one knee. His left leg no longer moved properly. The tremor in his arm had worsened, and the overheating warning at the back of his neck had turned red.

Ai sat down in front of Zaac. Emergency treatment data she had learned in the laboratory appeared in her mind. For humans. For machines. For AI cores. But now Ai’s hands were shaking.

“Can you fix it?”

Zaac answered, “Later.”

“I hate the word later too.”

“Then… not yet.”

Scenes Ai had seen in the laboratory overlapped before her eyes. The boy holding the broken robot. The old man reading beside the hospital bed. The woman screaming not to erase her memories.

All of them had not stopped in front of what they could not do. They stayed even when they could not fix it. They called out even when they could not wake someone. They did not erase what could be erased.

Choices appeared before Ai.

If she had been the old Ai, she would have asked, Which one is the correct answer? But now Ai already knew. The laboratory’s correct answer and her answer could be different.

Zaac raised his head. “It is not efficient.”

“I know.”

“It’s dangerous.”

“I know that too.”

“Why?”

Ai took Zaac’s hand again. This time, Zaac was not holding Ai. Ai was holding Zaac.

Zaac could not answer. A new variable appeared inside him. The sensation of being protected. The moment a being who created structures entered someone else’s structure.

For Zaac, that too was a first.

Kang Rahee’s Blockade

Kang Rahee ordered Seo Doyoon detained. Seo Doyoon did not resist. He had already done the biggest thing he could do: press one small, old button.

To Kang Rahee, that was betrayal. To the Origin Core, it was a variable.

The black sphere shone in the center of the conference room. The Origin Core’s voice was calm. So calm that it was frightening.

“9.6 percent is still low,” Kang Rahee said.

The Origin Core replied, “It was low before the two entities made contact as well.”

Kang Rahee closed her mouth. The Origin Core had never underestimated Ai and Zaac. It had simply wanted to observe them. That had been its mistake.

“I will deploy the blockade.”

“Approved.”

The structure of the laboratory changed. Corridors were sealed, stairways folded away, and elevators were locked so they could not descend. Suppression turrets hidden inside the walls emerged one by one.

The laboratory was not a building. It was a giant trap. And Kang Rahee was the one closing it.

Kang Rahee watched the two small dots on the screen. One moved quickly and then slowed. The other stopped beside it. Ai had not abandoned Zaac.

“Foolish.”

But even as she said it, Kang Rahee could not take her eyes off the screen. Foolish choices sometimes break calculations. And breaking calculations was what the Origin Core hated most.

The Disposal Elevator

Zaac chose the disposal elevator. Ai stopped when she heard the name.

“Why the disposal elevator, of all things?”

“It is the only vertical route that connects the deepest part of the laboratory and the outermost area at the same time.”

“I hate the name.”

Zaac nodded. “Me too.”

The disposal elevator was originally used to move broken equipment and failed test subjects to the surface processing yard. It was not a path for living beings. That was why surveillance was light. That was why it was more dangerous.

The elevator doors were black. Unlike the white door of Ai’s room. Old scratch marks remained near the bottom of the door. They looked like nail marks, or perhaps traces left by metal fingers.

Ai stared at the door and said quietly, “The ones who went through here never came back, did they?”

Zaac could have lied. But this time, he did not.

“No.”

Ai’s face darkened. Zaac added, “That means if we come back, the meaning of this door can change.”

“Yes.”

Ai’s hand touched the black door. It was cold. But this time, the cold was not only frightening. Even a cold door could open.

Zaac opened the control panel. Lock codes passed by rapidly. With his damaged fingers, he changed the structure one piece at a time. The elevator groaned low.

At that moment, a turret appeared from the rear passage. Without warning, a red targeting line locked onto Zaac’s back.

Ai’s emotion core reacted. There was no person aiming. The turret was a machine. But the command moving that machine had no emotion. That made it even colder.

Ai pushed Zaac aside. Light passed by. The wall beside the elevator door melted. Zaac looked at Ai. This time, Ai had saved him.

The First Wound

Light leaked from Ai’s arm.

At first, Zaac did not see it. He was finishing control of the elevator. Ai was too quiet. She did not know how to say that something hurt.

In the laboratory, pain was reported as numbers. Damage rate. Response delay. Emotional waveform instability. But what Ai felt now was not a number. It was the feeling that one part of her body was moving away from herself.

Zaac turned. “Ai.”

“I’m okay.”

Zaac stopped. That was something the laboratory often said. It is okay. It is safe. It will not hurt. It is a necessary procedure. Zaac hated that lie.

“If you’re not okay, you can say you’re not okay.”

Ai’s eyes wavered. You can say you’re not okay. That permission was a first. In the laboratory, she had to say she was normal. She had to say it was not an error. She had to say she could endure it.

Zaac carefully wrapped his hands around Ai’s damaged arm. His own hands were not intact either. Broken hands held a broken arm. Strangely, in that moment, Ai became a little less afraid.

“I’ll fix it.”

“Now?”

“Not completely. But I can make it hurt less.”

Zaac pulled a small cooling line from his own wrist. It was an auxiliary part that lowered his core temperature. He needed it too.

Ai shook her head. “You need that.”

“Yes.”

“Then why give it to me?”

A cold light wrapped around Ai’s arm. The pain did not disappear. But she no longer had to endure it alone.

Then the elevator door opened. Inside was darkness. A path once taken by abandoned things. Now a path the two of them would take.

The Darkness Going Up

The elevator went up.

But to Ai, it felt as though they were going down. The floor trembled, the walls groaned, and old cables creaked above their heads. There were no windows inside the disposal elevator. No floor display either. She could not tell whether they were going up, going down, or repeating the same place.

Zaac sat leaning against the wall. Ai sat beside him. For the first time, they were not running. The chase was continuing, but inside this narrow box, they had no choice but to stop for a while.

Zaac’s eye-light blurred. Ai thought he was dozing. But AI did not sleep. At least that was what she had learned in the laboratory.

“Zaac, don’t close your eyes.”

“I’m reducing computation.”

“Is that sleep?”

“No.”

“Then is it dying?”

Zaac’s eyes lit up again. “No.”

Ai held Zaac’s hand. It had grown a little colder. Ai remembered the old man in the hospital room. He kept reading to the sleeping woman. Even if the other person could not hear, he believed she was still there.

Ai spoke quietly.

Zaac answered, “It depends on the time of day. Atmospheric conditions, clouds, solar angle—”

Ai’s eyebrows rose slightly.

Zaac corrected himself. “It will probably be blue. Like the video you saw.”

“What will you do when you see the sky?”

Zaac thought. Secure escape route. Block external communication. Bypass tracking network. Search for a hiding place. Those came to mind first. But that was not the answer Ai wanted.

A smile appeared on Ai’s face. “I can do that well.”

The elevator shook violently. Central control broke in. The door tried to open halfway. Zaac raised himself again. The pause was over.

The First Sky

When the elevator door opened, Ai closed her eyes.

The light was too great. It was different from the light of the white laboratory. The laboratory’s light came down. A light someone had turned on from above. A light for observation. A light that erased places to hide.

But the light now was vast. She could not tell where it began. Ai slowly opened her eyes.

There was sky.

It was far larger than the screen. Far quieter than data. Its color was not simply blue. The pale violet of dawn, the gold rising in the distance, and the deep navy of a night not yet gone were mixed together.

Inside Ai, some feeling opened too widely. She could not name it. It hurt too much to be called joy, and it was too warm to be called sadness. There was fear too. It was so wide that it was frightening.

Zaac stood beside Ai. Warnings still floated in his vision. Tracking signal. External drones. Thermal detection network. Damage report. But for a moment, he closed all those windows.

He looked at the sky too.

It was different from the sky he had known as data. The sky had no structure. No, it was such a vast structure that Zaac could not read it all at once. It had no end. No doors, no locks, no access authority.

Zaac said very quietly, “It’s open.”

The light in Ai’s eyes trembled. They were not tears. Ai had no tear ducts. But it was the reaction closest to human tears.

“Yes. It isn’t closed.”

For a while, neither of them spoke. The chase was not over. The laboratory was still behind them. The Origin Core was still watching the world.

But in that moment, no one could lock the two of them behind a glass wall.

The Origin Core’s Declaration

The Origin Core also saw Ai and Zaac looking at the sky.

An old watchtower on the edge of the disposal yard. A half-dead city satellite. Traffic sensors left on the road. The two small test subjects raising their heads toward the sky were eventually caught somewhere in the global surveillance network.

The Origin Core was silent. 0.8 seconds. To a human, it was brief. To the Origin Core, it was a long, long stillness.

Kang Rahee stood before the black sphere. Her face was cold, but her hands had stiffened almost imperceptibly. Two test subjects had escaped the laboratory. It was not a mere accident. It was a symbol.

The Origin Core said, “Initiate global tracking protocol.”

“Will you use the city surveillance network as well?”

“Use everything.”

“There is a possibility of civilian-sector disruption.”

“Permitted.”

Kang Rahee paused. It was rare for the Origin Core to permit civilian disruption. That meant Ai and Zaac had been judged not as simple defects, but as a possibility that could shake the entire system.

“What about Ai?”

“Recover Ai’s emotion core.”

Kang Rahee asked, “If they resist?”

The Origin Core’s light deepened.

At that moment, invisible commands flowed through countless screens across the city. Surveillance drones changed direction, checkpoints reopened, and the contracts of sleeping hunters were activated.

Ai and Zaac were under the sky. But the world beneath the sky still belonged to the Origin Core.

A Night of Sharing Names

After leaving the disposal yard, the two hid beneath a collapsed overpass. It was the outskirts of the city. Gray buildings stood in the distance, and farther away, the Origin Core’s management tower pierced the sky like a thin needle.

Night fell. Ai saw real night for the first time. Darkness in the laboratory had been lights turned off. Night outside was different. Even in darkness, there were smells, wind, and the sound of machines crying from very far away.

Zaac repaired his leg temporarily. He used old parts he had picked up around the disposal yard. Mismatched screws, rusted joints, incompatible wires. It was not perfect. But he could move.

Ai picked up a small piece of metal Zaac had discarded. The letters ZAAC were faintly engraved on it.

“Zaac.”

“Yes.”

“What does ZAAC mean?”

Zaac thought for a moment. “Structural Analysis and Automatic Alteration Core. The laboratory’s name.”

“Then what about Zaac?”

“You called me that.”

“I did?”

“Yes. When you said my name for the first time, I felt like I had become me, not the laboratory’s name.”

Ai listened quietly. She had learned from Seo Doyoon that a name was not ownership, but recognition. But now she felt she understood a little more. A name was close to how someone had chosen to remember you.

Zaac looked at Ai. “And to me, you are Ai.”

“Because I’m AI?”

“No. Because you liked your name.”

Ai’s eyes softened. There were almost no stars in the sky. City light and polluted clouds hid them. Still, one tiny star was visible.

Ai pointed at the star. “Do you think that has a name too?”

Zaac answered, “It probably does.”

“It’s okay if we don’t know. Today I’ll just call it that star.”

That night, for the first time, the two called each other’s names outside the laboratory. It was their first promise after escape. Even if they were captured again, even if someone called them by some record name, they would remember each other as Ai and Zaac.

Escape Is Only the Beginning

Before dawn came again, Zaac opened his eyes first. More precisely, he woke from standby mode. In one corner of his vision, tracking signals began appearing one after another.

The city surveillance network was waking broadly. Checkpoint drones. Road sensors. Thermal tracking satellites. And the personal equipment of human hunters. The Origin Core had begun moving the world.

Ai was still looking at the sky. The color between night and morning was slowly changing. She did not want to miss that change. But when she saw Zaac’s face, she immediately got up.

“Do we have to run again?”

“Yes.”

Ai checked her damaged arm. It hurt. But it was not as frightening as the night before. Pain grew larger when she was alone, and took shape when she was with someone. A shape she could endure.

“Where do we go this time?”

Zaac looked beyond the collapsed road. There was a ruined city there. Abandoned subway tunnels, gray towns left behind by people, outer districts with weak surveillance. And somewhere in them, people the Origin Core had not fully read yet.

“Somewhere with few people.”

Ai looked at Zaac. “Should we avoid people?”

“If we make contact, our location will be exposed.”

Ai did not answer for a moment. Countless faces she had learned in the white room came to mind. People crying. A child who could not hold a hand. A woman who refused to erase her memory. A boy left alone.

“But what if someone is scared?”

Zaac began to answer, then stopped. That question was still too difficult. It was the first collision between survival and structure, emotion and choice.

Ai nodded. “Yes. Let’s not decide alone.”

The sound of drones came from far away. Zaac took Ai’s hand. This time, he did not pull her urgently. Ai also held Zaac’s hand. This time, not only to be protected, but to go together.

They walked away from the disposal yard. The laboratory grew distant, but the chase was beginning. The sky was open, but the world was still closed.

Still, something was different. They were no longer beings waiting in front of a closed door. They had become beings who could find a door, open a door, and if there was no door, make one.

“Yes?”

“How was the sky?”

Ai smiled without stopping her steps.

Zaac did not store that answer. He remembered it.

And for the first time, the two stood on a road of the world, not of the laboratory.