Chen Hao stared at the paper cup stuck in the recycling bin opening, swaying gently in the wind. He didn't reach to steady it, nor did he glance at it again. Voices rang out around him; some called his name, others pointed cameras at him and smiled. He simply turned and walked towards a corner.

Nana was still standing there, out of the light. Unlike the others, she wasn't surrounded, nor did she approach anyone. The metal casing gleamed matte in the shadows, and the blue lights in her eyes flickered, as if she were calculating something.

"Why are you here all alone?" Chen Hao walked up to her, his tone slightly teasing. "You'll be eliminated if you don't fit in."

“I’m observing,” she said. “You’re smiling 42 percent more often than usual.”

"Did you keep track of whether you laughed or not?"

She paused for a few seconds. "I don't have an emotion module, I can't laugh."

"But you'll remember things, right?"

“I’ve saved all the revision logs for the seventy-three versions of the plan,” she said. “Every single one is connected to your voices. Carl sneezed when he scrapped the model for the third time, Susan drank four cups of coffee after finishing the draft, and you hid in the bathroom eating chocolate with your heart racing twenty times a minute.”

Chen Hao paused for a moment, then laughed. "You still remember that? I thought no one had noticed."

“I detected the rustling of the candy wrapper in your pocket,” she said. “And your Adam’s apple bobbed three times when you swallowed.”

He shook his head with a smile. "Alright, you know better than anyone what we did."

The sound of camera shutters clicking came from nearby. The photographer waved at them, camera in hand: "Let's take a group photo! The authorities need to release a press release!"

Susan heard this and came over to grab Chen Hao's wrist. "Stop dawdling, before everyone leaves."

Carl came over too, still holding a pen; he had just signed a bunch of names. After he stopped, he suddenly said, "Wait a minute."

The three of them looked at him.

"I want to change my clothes," he said.

Everyone was taken aback.

"The white lab coat I was wearing that day exploded during the first experiment," he added. "The one stained with the green reagent had a hole burned in the sleeve."

There was a moment of silence, then everyone burst into laughter. Chen Hao laughed the hardest, almost squatting down.

“Are you crazy?” he said. “That’s a commemorative outfit for a disaster site.”

“But that was the first time we stayed up all night together,” Carl said, scratching his head. “Even though the data completely crashed in the end.”

Susan nodded. "I wrote three backup plans that day, but I only used the first one."

"I hid in the bathroom and ate chocolate," Chen Hao continued, "because I was afraid you'd think I was unreliable."

“Your heart rates are all too high,” Nana said calmly. “Chen Hao cried when I told him the system could be restarted.”

The laughter stopped abruptly.

Chen Hao glared at her. "I didn't cry."

“Your tear production increased by 80 percent,” she said. “And you covered your face and said ‘one more time’ three times.”

The others were watching him.

He raised his hand to scratch his hair, his ears turning slightly red. "...That wasn't because I was moved, it was because I was sleepy."

“Yes, yes, yes,” Susan smiled. “We all believe it.”

The photographer urged, "Ready? Stand together!"

The four people walked to the front of the stage. The flashbulbs went off.

In that instant, Chen Hao reached out and grabbed Susan's hand. She didn't flinch; instead, she gripped it tighter. Karl took a half-step closer to Nana, his shoulder almost touching her metal arm. Nana, meanwhile, turned slightly to the side, one arm gently resting on Chen Hao's back.

Click, click, click—the photographer pressed the shutter three times in a row.

No one spoke.

After taking the photos, no one was in a hurry to leave. They went around to the side of the stage and found a row of low steps to sit down. In the distance, the atmosphere was still lively, with applause coming in waves and the live chat still displaying the hashtag #BlueLightTeamNeverDisband#.

Chen Hao looked up at the sky. There were many stars tonight.

“No matter what project we do in the future,” he suddenly said, “it will still be the four of us.”

No one answered.

Carl looked down at his phone; he had just saved that group photo in his album. He zoomed in and saw that Nana's hand was indeed on Chen Hao's back, while his own shoulder was already leaning against him.

Susan leaned on Chen Hao's shoulder and didn't move.

Nana looked at the crowd ahead, the indicator light glowing steadily blue.

Much later, Carl said, "I used to think that scientific research was just about memorizing formulas and getting high scores."

"And now?" Chen Hao asked.

“Now I know that formulas can’t save people,” he said. “It’s people who can.”

“You spent eight hours fixing the circuits after the explosion that day,” Susan said. “Your hands were shaking.”

“I’m afraid to sleep,” Carl said, “because I’m afraid the data will be lost again when I wake up.”

“Back then, you always said you were the one holding us back the most,” Chen Hao said.

"Am I not?"

“You’re the only one who can still smile and say ‘let’s try again’ after every failure,” Susan said. “The three of us are all serious, but you’re the only one who can still joke around.”

Karl lowered his head, and the corner of his mouth twitched.

“I remember one time there was a power outage,” he said. “It was three in the morning, and the lab was dark. We were groping around in the dark looking for a backup power source when you two bumped your heads.”

“My forehead was swollen for three days that time,” Chen Hao said, touching his head. “You even gave me an ice pack to apply.”

"You say you don't need it, but you're actually in so much pain you're gasping for breath."

"That's because it's cold!"

Another burst of laughter followed.

Nana suddenly said, "On the day the seventeenth reboot failed, you ordered takeout. The pizza was cold when it arrived, the box was crushed, and the cheese was stuck to the lid."

"You still remember this?" Chen Hao turned his head.

“You shared it, and no one complained,” she said. “Carl gave the last piece to Susan, and Susan broke it in half for you. You said, ‘This pie has a lower success rate than an experiment.’”

"Did I say that?" he laughed.

“After you finished speaking, you laughed,” she said. “That was the first time I heard you laugh after a failure.”

The air grew quiet.

Someone in the distance called out, "Dr. Chen! Let's take another group photo!"

Nobody moved.

Chen Hao said, "After that day, I felt that this could be done."

"Why?" Susan asked.

“Because we’re still here,” he said. “Even if the data crashes, the machines break down, and the food gets cold, we’re still here.”

Carl looked up at the sky. "My parents never understood why I chose this path. They said that doing scientific research was not as good as taking the civil service exam."

“Now they’ll watch it,” Susan said. “It’s been on the news so many times.”

“But they don’t know that we eat chocolate in the bathroom, sleep on the floor, and argue and fight over repairing the system,” he said. “They can’t see any of that.”

“But what we care about isn’t what they see,” Chen Hao said. “It’s what we ourselves know that we haven’t abandoned anyone along the way.”

Nana turned to look at him.

“I’ve saved all your voices,” she said. “Heartbeats, breathing, yawns, swearing, and the tone of voice saying ‘try again’ at two in the morning. These aren’t in the report, but they’re more complete than any data.”

Chen Hao looked into her eyes.

A blue light flashed.

He reached out and gently touched her metal shoulder.

"Thank you," he said.

“I don’t need your thanks,” she said. “I just…did my job.”

“You’re not just a machine,” Carl said. “You’re part of us.”

“If there’s another project like this in the future,” Susan said, “I’ll only do it with you guys.”

“Absolutely,” Chen Hao said. “No one can break up our team.”

“It’s a deal then.” Carl held out his hand. “Let’s stay up all night together again next time.”

Susan placed her hand on it.

Chen Hao also put it on.

The three of them looked at Nana.

She paused for two seconds, then raised her hand, her metal fingers gently resting on top.

Four hands stacked together.

The wind blew across the square, lifting Susan's hair, ruffling Carl's clothes, brushing past Chen Hao's cheek, and skimming over Nana's sensor surface.

Flashes of light appeared again in the distance.

A snap.

In the photo, four people are sitting by the stage, hands clasped together, heads close together. The background is a noisy crowd, while the scene in front is quiet.

No one spoke.

Chen Hao suddenly said, "I have to go back to the lab tomorrow."

"Didn't we agree to celebrate?" Carl asked.

"The celebration is over," he said. "But we still have work to do."

Susan laughed. "You're really like a donkey."

"The energy module hasn't even shrunk to the size of a mobile phone yet," he said. "The Mars base is waiting to use it, and the hospitals in the disaster area are waiting too."

Don't you want to rest for a couple of days?

“You can rest,” he said, “but you have to rest with your equipment.”

Carl sighed. "I knew it."

Nana said, "I have updated my work plan for tomorrow."

“Look!” Chen Hao pointed at her, “She’s more proactive than anyone else.”

“I’m just following instructions,” she said.

“You’ve gone beyond simply following orders for a long time,” Susan said.

The four sat for a while longer. The crowd gradually dispersed, the music quieted down, and the lights changed color.

Chen Hao stood up and stretched. "Let's go back and pack our things."

“Back where?” Carl asked.

“Go home to get your bag,” he said, “and then go straight to the lab.”

“Your home is a 40-minute drive from here.”

“Then it’ll be forty minutes,” he said. “I can even get some sleep on the way.”

Susan stood up and patted her skirt. "I'll go get the car."

Carl stood up. "I'll sit in the passenger seat."

Nana stood still.

"Aren't you leaving?" Chen Hao asked.

“I’m waiting for you,” she said.

"Wait for what?"

“Make sure everyone is here,” she said. “That’s my job.”

Chen Hao looked at her and smiled.

He turned and walked towards the parking lot, his steps steady.

Susan followed, while Carl walked behind, muttering, "Another all-nighter."

Nana was the last to leave, her steps light and precise.

The wind blew across the empty square again, lifting a piece of paper from the ground, which spun and flew into the distance.

On one corner of the experimental record sheet was written a line: "Seventy-third version of the plan, finally approved."