He made tea by habit.

He was aware of this as it was happening — aware that he had moved to the kitchen and filled the kettle and set it on the heat and was reaching for the cup before the full cognitive weight of the morning had caught up with his hands. His hands knew the ritual. His hands had been performing the ritual for five active decades: two cups on the days when he was thinking about the letters she had left and needed the comfort of the parallel action, one cup in the specific position on the corner of the desk before the Tide came. His hands were in the middle of the ritual before he had decided to perform it.

He set the second cup on the corner of the desk.

He looked at it. He looked at Iris, who was standing near the window looking at the tree, which she had described to him in Year Three of Cycle Three and which she was now looking at from inside the same room rather than from the other side of ten years of frozen time. She was looking at the tree with the specific attention of someone verifying a piece of data they have been holding in theoretical form and finding that it corresponds to reality and also exceeds it.

He said: "The tea is on the desk."

She turned from the window. She looked at the cup. She looked at him.

She said: "I know." A pause. "Thank you."

Neither of them said anything about the fact that she could not drink it. He thought: she knows I know she can't drink it, and I know she knows I know, and the cup is on the corner of the desk, and the corner of the desk is where it goes. Some forms of communication did not require the thing communicated to be possible in order to mean what it meant.

She came to the desk and sat in the chair across from his drafting table — the chair that had always been hers, the chair he had positioned at the beginning of Cycle Two and not moved since, the chair where a person sat when they were in this room with him for reasons that had nothing to do with being across the desk from him because no one had ever been across the desk from him in this room. She sat in it now, the chair finally occupied by the person it had been waiting for, and she looked at the cup on the corner of the desk and he looked at her looking at it.

He said: "Tell me what you need me to understand about your current state."

She nodded once. The nod of a person who recognized a useful opening and would move through it without delay. She said: "I can move through solid materials. I cannot touch or be touched through them in the usual sense — there is a sensation associated with contact but it is not what you would expect. I can be seen and heard. I can see and hear normally. I do not need food or sleep in the way I did before, though the archive suggests that both are advisable for slowing the deterioration rate." She paused. "The deterioration is ongoing. The mechanism I am now subject to is different from the absence-pathway mechanism, faster in its baseline rate. The Case Nine reversal data suggests that direct engagement with the attachment object can modify the rate — I am hoping the hypothesis holds. I don't yet have enough data."

He said: "How long have you been in this state?"

She said: "Since approximately two in the morning. The Tide turned four hours after the procedure completed, which is consistent with my timing calculations." She looked at him. "You woke at the usual time."

"Yes."

"Was anything different?"

He thought about this. He said: "The house felt wrong before I understood why. The absence of the letter on the desk. The containment case open." He paused. "And then I heard you in the corridor."

She said: "What did it sound like?"

He thought. He said: "Like something that was present in a way that hadn't been present before. I didn't have a prior category for it. I still don't."

She said: "The acoustic signature of an Echo is documented in the archive as — " and then she stopped. She looked at him and said: "I was about to cite the archive."

He said: "I know."

She said: "I do that when I am uncertain how to respond to something that is not primarily academic."

He said: "I know that too."

The look she gave him had the quality of someone encountering evidence that their correspondence had communicated more than they had calibrated for, and finding this simultaneously alarming and correct.

He reached for the notebook on the desk — not her research notebook, his, the one he kept for project notes — and his hand passed through her arm.

He stopped.

The sensation was what she had described: not nothing, but not the expected thing. A pressure translated into a register that his nervous system had no prior vocabulary for — the specific wrongness of matter not behaving as matter. He had reached without thinking, the way he reached for things in his own study, and found that the ordinary action produced an extraordinary result.

He looked at his hand. He looked at her arm, which had not moved.

He said: "I'm sorry."

She said: "Don't apologize. The instinct is reasonable. You'll do it again before the morning is over."

He said: "Is it — does it feel like anything on your side?"

She considered this with the specific quality of attention she gave to phenomena she was experiencing for the first time and had no prior literature to compare against. She said: "Not in the tactile register. There is something. I haven't categorized it yet." She looked at him. "I'll let you know when I have."

He put the notebook where he had been reaching for it and opened it instead. He held the pen. He said: "Tell me about the letter."

She said: "Which one."

"Mine. In the drawer."

A pause. She said: "I found it on a Tuesday in Year Three. I had gone to the drawer for a pen." She paused. "I read it twice before I read the rest of my correspondence that morning. Then I read it a third time in the evening."

"And then?"

"And then I read my own unsent letter. The one I had put in the drawer in the previous cycle." She paused. "I read them together. Side by side." She looked at the drawer. "They said the same thing."

He said: "They said different things."

She said: "They described the same problem from different approaches and proposed different solutions that were both oriented toward the same objective." She paused. "Which is another way of saying they said the same thing."

He thought about this. He said: "My solution was to leave."

"Yes."

"You didn't let me."

She said: "You didn't finish packing."

"No."

"Why not?"

He held the pen without writing. He said: "Because I put the letter in the drawer and then I stood in the corridor outside the storage room with my hand on the wall you modified and I thought about the fact that I had built the stability in that wall for you to use and I didn't know what you would use it for, and I found I could not leave without knowing." He paused. "Which was not a reason I had planned on."

She was quiet for a moment. She said: "You modified the corridor wall using the specifications from my published research on cross-section stability."

"Yes."

"You sourced a specialized plaster formulation from a restoration supplier three cities away."

"Yes."

"And installed it yourself, which took approximately two weeks based on the area and the formulation's working time."

"I like working with my hands."

She looked at him with the expression she wore when someone had said something that required filing under a category she had not previously defined. She said: "I knew you had done it. I read about it in your letter from the end of the previous cycle. I understood it intellectually." She paused. "Understanding it while standing in the corridor using the Zone that was stabilized by the wall you built is different from understanding it intellectually."

He said: "Different how?"

She said: "Larger."

He wrote nothing in the notebook. He put the pen down and looked at her across the desk and thought about forty years of letters and the specific quality of being in the same room as the person you had been writing to, which was not smaller than the letters — was not a reduction of them or a replacement — but was the letters and also something that the letters had not had room for.

He said: "What do you need? Practically. For the next days."

She said: "I need to document what is happening as it happens. The data is specific to my case and there is no prior documentation of this experience from the inside." She paused. "I need to understand the Zone as it expands. I have theoretical predictions but the propagation rate is faster than my central estimate and I want to understand why." She paused again. "I need — " She stopped.

He waited.

She said: "I need you to be here. That is the variable I have not been able to test. That is the thing the Case Nine data suggests matters. The presence." She looked at him directly, with the look she had given him in the corridor — direct, willing to see. "I need you to be here."

He said: "I'm here."

She said: "I know." A pause. "I'm documenting this. The sensation associated with that statement is also data."

He said: "What is the sensation?"

She said: "I'm still characterizing it." But something in her look shifted — the window-opening quality again, the few centimeters of additional air — and he thought that whatever she was characterizing it as, it was not nothing, and it was not what it had been before the morning.

He extended his hand across the desk. Slowly, deliberately — not the reaching-without-thinking of the notebook incident, but a considered movement with a specific intention. He extended his hand palm-up across the surface of the desk, in the space between them.

She looked at it.

She extended her hand toward it.

Her hand hovered above his — they could both see exactly where contact would be, the specific geometry of the almost-meeting. His hand below, palm-up, the lines his profession had written into it across forty years. Her hand above, palm-down, the fracture on her wrist visible at this proximity in its full silver-gray iridescence.

Neither of them moved closer.

He said: "Tell me when the mechanism changes."

She said: "You'll be here when it does?"

He said: "I'll be here."

She withdrew her hand slowly. He withdrew his. The space between them on the desk surface was the space between them: specific, measurable, currently unbridged.

From the library down the corridor, there was a sound — not the house settling, not the Zone's low resonance, but a different quality. The sound of a door that was not a current door being encountered by the light of a different hour.

Iris turned toward the sound. She said: "The Zone is into the library."

He said: "Is that — "

She said: "Expected, yes. I predicted it would reach the library by late morning." She stood. "We should go see which cycle it is."

He stood. He picked up his notebook and pen. He said: "You predicted."

She said: "I've been researching temporal anomalies for thirty years. I have some predictive capacity." She moved toward the corridor. "Also I know this house. I know which walls are most susceptible to the propagation effect based on their material composition and proximity to the initial cross-section."

He said: "You've been mapping the house's vulnerability to temporal cross-sections."

She said: "I've been mapping it since Year Two of Cycle Three. When you modified the north library wall in Cycle Four, I had to revise the model." A pause. "The revision improved the predictive accuracy."

He said: "I wasn't aware I was contributing to a temporal vulnerability model when I modified the north library wall."

She said: "You were primarily contributing structural improvement. The temporal vulnerability was a secondary effect." A pause. "A useful one."

He followed her down the corridor toward the library and the sound of a door that opened onto a different time, and he thought about forty years of letters and forty years of building responses to letters and the specific quality of doing both of those things in the company of the person they had been addressed to, which was the quality he had been calling, in various forms, the reason he had not finished packing.