The mobility protocol came together more easily than he had expected.

He had anticipated the same kind of work as the dispersal protocol — working through edge cases, failure modes, the specific scenarios where things could go wrong. But the dispersal protocol had been built for a situation they were trying to prevent, and the mobility protocol was built for a situation they were trying to enable, and that turned out to be a meaningfully different kind of work.

He sat at the desk with the System open. Mien sat beside him — at the desk, not the spare chair, where they both had sight lines to the relevant screens.

"The baseline," she said. "What does cover look like when Thần is moving rather than stationary?"

"Moving cover is less precise," he said. "Stationary, I can configure the suppression to a specific volume. Moving, it needs to follow. There's a lag — about two seconds between position change and cover reconfiguration."

"Two seconds where the signal peaks slightly?"

"Yes. Not enough to register on Traffic's standard equipment. But we should know it's there."

She made a note.

"Protocol rule one," she said. "Thần moves slowly. No rapid repositioning."

"Yes." He thought about what he had seen on the sensor logs — the way Thần moved when it came to the corridor. "I don't think it will be a problem. It moves the way it's been moving."

"It's cautious," she said.

"Yes."

They worked through the access framework: which spaces, which times, which conditions. The answer turned out to be simpler than he had projected. Common areas, any time. Upper floors, when residents were not in the corridors. The courtyard, after dark. Outside the building, not without one of them present.

"The resident interaction risk," he said. "If a resident encounters Thần in a corridor, Thần needs time to adjust visibility."

"How much time?"

"Three to five seconds. Signal protocol through the contract link — a specific flag. If a resident rounds a corner into a corridor where Thần is, the flag goes to both of us and Thần simultaneously."

She looked at the screen. "Thần can receive that through the contract?"

"SS-class management protocol. The link is bilateral — I've been using it for passive monitoring. Active signaling is the same infrastructure."

She made a note.

"Three seconds is workable," she said.

"Yes."

He built the flag configuration. She watched and annotated. By noon, they had a draft.

She read through it.

"It's simpler than I expected," she said.

He looked at the draft.

"Thần did the hard part," he said. "Learning to manage its own output while moving. The protocol just defines the operating space."

She looked at the draft. "It knew what it needed. We gave it somewhere to do it."

He looked at the draft.

He thought: yes.

---

At two-seventeen, the internal sensor flagged.

Thần, basement stairs, ascending.

He watched the camera. Mien watched the camera.

Thần moved down the corridor — the full length of the ground floor common corridor, slow and deliberate, the quality of something that had a map and was verifying it against the territory.

At the far end of the corridor, there was a window.

The east window. The direction things had been coming from for most of the past two months.

Thần stopped at the window.

It stood there.

Mien said: "It's at the east window."

"Yes."

"That's the direction it came from. Grid F-9 is east of here."

He looked at the camera.

He thought about Thần in the demolished structure in grid F-9, holding its signal down for months, trying not to be found. He thought about what the city must look like from that window — not the city it was looking at now, but the city it had known from inside the structure, the ambient light and sound of a world it had been trying not to disturb.

Thần stood at the east window.

Eight minutes.

Then it turned and went back to the basement.

Movement log: Thần: floor 1, corridor east, east window, 8 minutes. No resident contact.

He wrote in the note field: First window.

---

That evening, he said: "It stood at the east window for eight minutes."

"Yes," she said.

"That direction. That's where it came from."

"Yes."

He looked at the east window of the room.

He said: "Do you remember the first morning you looked out the window?"

She looked at the window.

"Yes," she said. "It was louder than I expected. The city."

"I was at the desk," he said. "You were on the sofa."

"You didn't say anything."

"No."

"But you were there," she said.

He looked at the window.

"The first morning I looked out the window," she said. "You were standing there. At the desk. Not doing anything, just — being there."

"Yes," he said.

"You're still standing there," she said.

She said it in the specific way she said things that were true and that she wanted to be registered as true — not as a question, not as a bid for something, just as a statement of what was.

He looked at the window.

He thought about fifty-nine days and the desk and the window and the east direction.

"Yes," he said.

She looked at the window.

He looked at the window.

Neither of them said anything for a while.

Then she went back to the notebook.

He went back to the log.

---

The next day, Mrs. Nam came at six.

She had steamed buns and sat in her chair and gave one to each of them and talked about the district council meeting and the neighbor's new cat and the vendor who had moved tables.

At some point she looked around the room.

She said: "It feels like there's more people in here lately."

He looked at her.

Mien looked at him.

Mrs. Nam was eating her bun with the equanimity of someone who had said what she noticed and was not invested in the response.

"Mien's friend comes by sometimes," he said.

Mrs. Nam looked at him. "Friend?"

"Someone she knows. Comes to visit."

Mrs. Nam looked at Mien.

Mien said: "Yes. They don't stay long."

Mrs. Nam considered this.

"A good friend?" she said.

He looked at Mien.

"Yes," Mien said. "A good friend."

Mrs. Nam nodded with the nod of someone filing satisfactory information.

"Good," she said. "A house should have more than one person in it."

She ate her bun.

---

After Mrs. Nam left, the room was quiet.

After a moment, Mien said: "Mien's friend."

He looked at her.

There was something at the corner of her mouth — not a smile exactly, the expression of someone who found something accurate-and-also-unexpected.

"Yes," he said.

"Thần would like that," she said. "If it knew."

"It doesn't know."

"I'll tell it in tomorrow's session." She looked at the notebook. "Not the words. The quality of it. That it's considered a friend here."

He looked at the room.

He thought about the quality of being considered a friend here. The things that constituted friendship in this specific building: buns and regular visits and Mrs. Nam filing satisfactory information.

He thought: that's what household means.

He looked at Mien.

She looked at him.

The look across the room — the one they had been exchanging for sixty-some days now. No content beyond the fact of it.

He held it for a moment.

She held it.

Then she looked at the notebook.

He looked at the log.

---

Day sixty-three.

Ambient: fifteen point zero.

"Fifteen point zero," she said, at the display.

"The threshold is fifteen," he said. "We're there."

She looked at him.

He looked at the display.

Forty-two days ago this number had seemed very far away.

"Good morning," he said.

She looked at him.

"Good morning," she said.

She went to make tea. He watched her go.

---

At two, he ran the partnership visit preparation.

Fixed-array scanner: threshold eighteen to twenty percent. Gen-4 portable: threshold nineteen to twenty percent. Combined ambient: fifteen point zero.

Clear, at five points below the lower threshold.

He noted it.

He looked at the contract review: Day 90. 24 days.

Same day.

Sub-threshold confirmed on the same day the contract review opened.

He had not planned that. The math had worked out that way because he had arrived at sub-threshold faster than projected, and the contract review was fixed.

He looked at both dates.

He thought: same day.

He thought: that seems right.

Mien came in from the afternoon session.

She said: "You have the expression you have when you've noticed something."

"The contract review and the sub-threshold are on the same day," he said.

She was quiet.

"Twenty-four days," she said.

"Yes."

"That's also the week of the second partnership visit," she said.

He had not calculated that. He looked at the schedule.

She was right.

Three things on the same day. Or nearly.

"They're all the same kind of thing," she said. "All of them — endings of a waiting period. Beginnings of whatever comes after."

He looked at the three dates.

"Yes," he said.

She looked at the window.

He looked at the window.

Twenty-four days.

---

That evening she said: "Thần went back to the east window today. Twelve minutes. Longer than yesterday."

"Is it looking for something?" he said.

"Looking at something," she said. "Watching. The distance between there and here. I think it's measuring something. The distance it's traveled."

He looked at the east window.

He said: "I've been doing that too. Measuring the distance between day one and now."

She held his gaze.

"It's a long distance," she said.

"Yes," he said. "And also not."

She was quiet.

"Both," she said.

"Both," he said.

He looked at the window.

She looked at the notebook.

After a while they both went back to work.

---

He wrote the log entry at ten.

Day 63. Ambient 15.0. Sub-threshold reached — confirmed. Contract review Day 90 = 24 days. Second partnership visit: same week. Note: three things at once. All endings of a waiting period. Beginnings of whatever comes after.

He added: Thần: east window, 12 minutes. Measuring distance.

He looked at both notes.

He thought: I have been keeping a log like this for three years and I have never written anything like this.

He thought: yes, and I'm writing it anyway.

He turned off the lamp.

In the dark, the city ran its cycles. The ambient was fifteen point zero. Thần was in the basement. Mien was asleep.

He thought: twenty-four days.

He thought: three things at once.

He thought: both.

He sat in the dark for a long moment with all of it.

He thought about the building — what it had been, what it was now, what it would be after twenty-four days.

He thought about the person on the sofa who had been here for sixty-three days and had said "you're still standing there" and had looked at him across the room with the look that needed nothing added to it.

He thought: twenty-four days.

He thought: and then whatever we want.

He went to sleep.