In the three years since Yuki Nakamura had come through the portal, she had learned everything she could about Polaris City.
This was not because she was curious by nature — though she was — or because knowledge was comforting in an uncomfortable situation — though it was. It was because Yuki Nakamura was sixteen years old and deeply, fundamentally practical, and the first thing any practical person does in a new environment is figure out how it works. You cannot escape a system you don't understand. You cannot navigate a world you haven't mapped.
She had spent her first week in Polaris City learning the grid.
The city was divided into seven radial sectors, each further divided into thirty-two altitude zones. Zones one through eight were the upper rings: wealthy, well-lit, with air that smelled of ozone and filtered water and the particular crispness of an environment maintained by excellent technology. Zones nine through sixteen were the middle rings: working-class in every sense — the people who kept the upper rings running, who maintained the electromagnetic platforms and operated the transit systems and grew food in hydroponic towers and made the things the upper city consumed. Zones seventeen through twenty-four were the lower rings: the old infrastructure, the parts that had been there the longest, where the city's original population lived without the benefits of the newer systems above. Zones twenty-five through thirty-two were below the permanent cloud layer, accessible only by one specific transit line, and Yuki had not gone there yet. The people who lived there, she had been told, had a different relationship with the concept of up.
She had spent her second week learning the credit system.
Credits were oxygen in Polaris City. You earned them through registered labor, which required a city identity, which required a birth registration in the city's system, which was assigned at birth in the city's medical registry, which you could not retroactively obtain. Unless — and this was the seam she'd found, the hairline crack in the otherwise airtight system — you were a minor. Minors had a sixty-day grace period before identity registration was required, during which they could access the city's juvenile welfare provisions: housing, nutrition allocations, medical care.
She had used this grace period to establish herself.
By the end of sixty days, she had a network.
Not a large one — Yuki was efficient, not ambitious. A handful of contacts in the middle rings who owed her small favors: a transit worker who looked away when she used certain corridors, a hydroponic technician who understood that waste had to go somewhere and Yuki was very good at finding it a purpose, two children from Zone 22 who were smart and hungry and had learned that Yuki's version of hungry was different from theirs and still managed to be the same.
The three children Riku had tried to help were hers. The whole thing had been a calculated test — she needed to know if the trial person (and she had felt the portal open, had felt it the way you feel a change in air pressure before a storm, the frequency of it unmistakable once you'd been through one yourself) was going to walk past. Most people walked past.
Most trial people walked past, because they were scared and alone and looking for the quick exit. The ones who stopped — the ones who made the harder choice first — those were the ones who were actually ready to go home.
She explained some of this to Riku through the cell door slot.
He listened well, she noted. He didn't interrupt except to clarify, and his clarifying questions were good ones: precise, targeted, indicating that he was building a model rather than just collecting information. An engineer's mind, or something like it.
"Your trial," he said, when she'd finished explaining the test. "You said you've been here three years."
"Yes."
"That means you haven't completed it."
"Gold star."
"Why not?"
Silence from the other side of the door. A different silence than the tiredness she'd spoken with earlier — more contained, more deliberate. The silence of someone who has an answer they're deciding whether to share.
"Because completing my trial means going home," Yuki said finally. "And going home means accepting that my sister didn't make it through. And I haven't —" A pause. "I haven't found enough to be sure about what happened to her. I haven't found out if she's here somewhere, in the system, or if she's —"
She didn't finish the sentence.
Riku sat on his bench and listened to the particular quality of her not-finishing it.
"Your portal only opened three times," he said.
"Yes."
"And there were four of you."
"Me, my parents, and Mei. My sister. She's eleven."
"Was eleven."
"Is eleven. She is eleven. She's somewhere."
He heard the steel in it and did not argue. He understood that particular grammar — the present tense used for someone whose status was uncertain, because the past tense was a door you couldn't un-open.
"Okay," he said. "So you've been looking for her for three years."
"I've been looking for her for three years. My parents completed their trials in the first month — they didn't know about Mei, the system didn't tell them, they were just trying to get through and get home. They made it. I sent them ahead because I couldn't make them stay here in a trial environment that was already unstable, and I thought — I thought I'd find her faster than I did."
"And?"
"Three years is a long time to look for someone who may not be findable."
Riku absorbed this.
"The system," he said. "The trial system. Do you know how it works? From the inside?"
"More than any trial person should, probably."
"The man who built it — or a version of him — he said the trial environments become permanent if you don't complete them. What does that mean, exactly?"
A long pause from Yuki's side.
"It means the border hardens. The environment stops being a corridor and becomes a room. And the people in it stop being visitors and become —" She seemed to search for the word. "Residents. Permanent residents of a space that was never designed for permanent habitation."
"But they're alive."
"They're alive. They're intact. They have their own physics and their own time. But they can't leave. And neither can the people who stay trying to find them."
There was something in the way she said this that told Riku she was not speaking hypothetically.
"How many people are stuck?"
"In this environment alone? Fourteen. Polaris City is the most common trial environment for people with my kind of —" She paused. "My family's patterns. Boundaries and hierarchies and who gets to belong. So we get the city that runs on belonging. Fourteen people, across seven different trial families, who've stayed past their completion window and are now permanent. And one eleven-year-old girl who may be one of them."
The slot in the cell door opened. A hand pushed through — small, brown, scarred along the thumb from a tool of some kind — and left a folded piece of metal: a simple shim, the kind of thing you use to manipulate door mechanisms. "I can get both of us out in three minutes," Yuki said. "But I need you to do something for me first."
"What?"
"Complete your trial first. Find your portal, go home, make it through the nexus."
"What does that have to do with —"
"When a trial completes, the system logs it. It creates a pathway record. I've been trying to access the pathway records for the incomplete trials — for the fourteen stuck people and my sister — for three years, and I can't reach them because I'm inside the system and unverified. But when you complete your trial, your pathway record gets written, and for approximately forty-eight hours, the system's verification layer is open to adjacent records."
"You need me to complete my trial so you can piggyback on my verification to access the system files."
"Yes."
"And then?"
"And then I'll know where Mei is. And if she's findable, I'll find her. And if she's not —" A pause. "At least I'll know."
Riku thought about it for exactly as long as it took him to know what he was going to say.
"Deal," he said. "Get me out of here and show me where my portal is."
— ✦ —
He heard the sound of Yuki working the cell door mechanism — fast, practiced, the sound of someone who had done this before. Three minutes, she'd said. It took forty seconds. The door swung open and he saw her for the first time: sixteen, compact, with a face that had been young once and was currently in the process of becoming something else, and eyes that catalogued him in the same fast, efficient way he'd been cataloguing everything since he arrived. She looked at him for exactly two seconds. Then she said: "Your trial's in the lower rings. Zone 29. Below the clouds." She paused. "I've been down there twice looking for Mei. I need you to know something before we go." "What?" "The people down there — the permanent residents — they know what they are. They know they're stuck. And some of them have decided that if they can't leave, they're going to make sure no one else does either." The city's lights went amber. Above them, through the tower's ceiling panels, something enormous moved.