By the end of the first week, they had a routine.

Valerius arrived at the cathedral at the third hour past noon, which was when the winter light came through the east-facing gaps in the walls at the most useful angle, filling the nave with that particular flat illumination that was neither warm nor cold, only present. Aurelia was always already there. He had not managed to arrive before her, and he had tried, once, on the fourth day, and she had still been there — sitting with her back against the large cherry tree, eyes closed, apparently asleep, except that she had said you are twelve minutes early without opening her eyes the moment he stepped through the entrance.

He had not tried to arrive before her again.

The sessions had a shape. They began with what Aurelia called warming the room — she would move through the nave in a slow, deliberate sequence while Valerius tuned Aetheris and allowed himself to exist in the same space as the violin without the tuning becoming an obstacle in itself. He had learned, over the first few days, that the act of preparation was itself a kind of practice. The careful rosining of the bow. The tightening of the hair. The tuning — Aetheris, which had always had strong opinions about how it liked to be tuned, had begun, very quietly, to have opinions again, the strings settling at certain intervals with a warmth that suggested they approved, and drifting sharp at others as if registering a complaint.

It was not much. But it was more than nothing, which was where they had started.

On the seventh day, he tried to play through the full opening phrase of the piece they had decided to use for the competition — a traditional Oakhaven form in three movements, structured enough to give the judges a recognizable frame and flexible enough to accommodate the improvisational quality of Weave-Dancing. He had written a new arrangement of it over the previous four days, working at his desk in the evenings, and had been reasonably satisfied with what he had produced.

He got through the first eight bars without incident. Then the mental block arrived.

It was always at a specific place — not the same bar every time, but always a certain quality of moment, a point in the music where the emotional content of the phrase required something more than technical execution. His mother's voice: not felt. And the moment he thought that, the Resonance would begin to flicker, Aetheris would go thin and reluctant under his bow, and the phrase would die.

He put the violin down. Set it on the altar steps with a care that was slightly too deliberate, the care of someone managing a reaction rather than having it. Stood.

Aurelia was still dancing.

She had not stopped when the music stopped. She was on the other side of the nave, in the sequence that built toward what they had been calling the third movement, and she continued it without music — working through the phrase in silence, her feet finding the gaps in the broken paving with their habitual surety, the cherry trees pulsing softly in response to each step. She looked as if the music's absence was simply a different condition to work in, neither better nor worse, just different.

Valerius stood beside the altar steps and watched her.

She danced three full repetitions of the phrase before she stopped, and when she stopped it was with the same completeness as always — a decision, not a trailing off, the motion ending at a specific point and then simply being done. She stood for a moment looking at the far wall, her breathing visible in the cold air.

She did not ask what happened. She did not turn to look at him. She did not fill the silence with the careful performance of not-noticing that most people deployed when something went wrong and they were trying to be kind about it.

She just started from the beginning of the first movement again.

From the beginning. All the way from the opening phrase, working through it at half-tempo without music, her feet marking the rhythm on the stone floor, the cherry trees registering each step with their small luminescent response.

Valerius watched her for a moment.

Then he picked up Aetheris.

He did not start at the beginning. He started four bars before the place where the phrase had died — gave himself a running approach, the way one takes a longer runway for a difficult landing — and played toward the obstruction and through it. Not without resistance: the Resonance flickered, Aetheris went reluctant, the mental block arrived as it always arrived. But he had played through it by a bar before he recognized that he had.

He stopped, because he did not trust what might happen if he continued without understanding what had just changed.

The cherry blossoms were drifting around both of them, the Resonance pulse larger and more complex than it had been before — both their contributions present in it now, interacting in the way that made it more than the sum of its parts.

Aurelia was looking at him.

Three more bars, she said. We will add three more tomorrow.

It is not a question of length, he said. The obstruction is not structural. It is — he stopped. He was not sure he was going to tell her what it was.

I know, she said, which he had not expected. Not I know like I understand the concept but I know like she knew the specific thing he had not finished saying. She turned back to the cherry tree without elaboration, which was also unexpected. Most people, when they said I know about someone's grief, wanted to be credited for the knowing.

She simply knew and moved on, and this was, he found, a significant relief.

He played the four bars again. And then three more. And then, because he had gotten that far and the obstruction did not return with the same force when he was moving through rather than stopping at it, three more after that.

At the end of the tenth bar he looked up and found that Aurelia had reconfigured her sequence in real time, extending the phrase to match his expanded run, her footwork adapting without the hesitation that would have indicated she was calculating rather than hearing. She was hearing him — not just the notes but the intention behind them, the specific quality of musical attention he was bringing to each phrase — and responding to it, and the cherry trees above them were doing something he had not seen them do before.

All three of them were responding. Not just the large central tree but the two smaller ones growing up through the paving on the eastern side, their blossoms pulsing in a slightly different frequency, and the three frequencies were combining in the stone below his feet in a way that he felt before he heard it: a deep, slow resonance, nothing like the engineered crystals of the upper city, something older and more fundamental, as if the cathedral itself were waking up.

Aurelia felt it too. He could see her feel it — the slight alteration in her posture as the resonance moved through the floor into her feet, the way her movement adjusted to accommodate the new frequency rather than fighting it. She looked surprised. It was the most unguarded expression he had seen on her, in a week of expressions she managed with considerable skill.

The moment lasted perhaps fifteen seconds. Then the Resonance settled back to its usual level, the blossoms steadied, and they were both standing in the ordinary quiet of the cathedral with their respective instruments and the fading luminescent drift of disturbed cherry flowers around them.

What was that? Valerius asked.

I do not know exactly, she said, which he was almost certain was true and possibly the first entirely unqualified truth she had told him. She was looking at the floor, where the Resonance pulse had originated — at the root system of the central cherry tree, specifically. Something the trees do sometimes when the conditions are right.

What conditions?

I have not been able to figure out the full set. She crouched and touched the root nearest to her, very lightly, and the wood beneath her fingers gave a single slow pulse of light that traveled outward and faded. I know it is related to authenticity. The trees do not respond to performance the way they respond to the actual thing. Whatever the actual thing is. I have been trying to produce it reliably for three months and I have only managed it a few times.

Harmonic Surge, Valerius said. The preliminary stage. When two Cadence Wielders with compatible Resonance begin to interact, the ambient Cadence in a site like this amplifies their combined output. It becomes a feedback loop.

Is it dangerous?

He thought about it. At low levels, no. At high levels — he considered the texts. At high levels it can become self-sustaining. The Resonance amplification exceeds the input, and the surplus has to go somewhere.

Where does it go?

It depends on what the Cadence Wielders are doing with it. He looked at her. In a combat context, destructive. In a performance context — he had read descriptions. He had never witnessed it. Accounts describe it as overwhelming. For the audience. For the performers. The kind of experience people build myths around.

She was quiet for a moment, looking at the root.

We should probably not let it get to that point, she said, at the competition.

Almost certainly not.

Almost, she repeated, and there was something in her voice — not lightness exactly, not the performed version of it, but a genuine and slightly reckless quality that he found, without entirely wanting to, interesting. She stood and stretched, the long muscles of her back and arms. Again from the beginning?

He looked at Aetheris. The strings were warm under his fingers — warmer than they had been at any point in the past six months. Not the full warmth of Aetheris at its best, nothing like the resonant heat it produced during genuine Cadence Manipulation. But warmer than thin. Warmer than ordinary wood.

From the beginning, he confirmed, and raised the bow.

They played until the winter light shifted and the east-facing gaps in the walls went cold, which was approximately an hour, and at the end of it Valerius's bow arm had the bone-deep tiredness of sustained effort and his right-hand fingers were showing the early traces of the specific calluses that Aetheris strings required, the slight reddening of skin that would, in a week, become the hardened ridges he had maintained for nine years and lost in six months.

He packed Aetheris away while Aurelia rolled the scrolls of notation he had been using to follow his arrangement. She had learned to read his handwriting in the first three days, which had required approximately no adjustment on her part; his handwriting, which his mother had called adequate and three Academy instructors had called challenging, apparently presented no difficulties to her.

She handed him the scrolls without comment. He put them in the case.

Your left hand, he said. The stiffness in the joints. How long has it been?

She went very still.

Not for long — a fraction of a second, less than a breath. But he had been watching her for a week and he knew how she moved and he knew this stillness for what it was.

I slept on it wrong, she said, and the sentence was perfectly smooth, and he recognized the smoothness and filed it away and said nothing.

Make sure you warm them before you practice, he said. Cold joints in a Weave-Dancer are a technique problem waiting to happen.

She looked at him for a moment with an expression he had not seen before. Something in it that was, underneath the surface, not quite smooth. Then it resolved into the familiar version of her, the performed one.

Yes, Maestro, she said, and there was enough irony in the title to constitute a small joke, but something under the irony that was not a joke at all.

He left without responding to it. On the walk home he thought about the warmth in Aetheris's strings, and the three cherry trees responding in concert, and the Resonance moving through the stone floor into his feet. He thought about ten bars, and what ten bars meant after six months.

He arrived home to find that he was hungry — genuinely, specifically hungry, aware of his body in the way that six months of grief had largely suppressed — and went to the kitchen and ate what was there, standing at the counter, without ceremony or the careful observation of mealtimes his mother had maintained.

The cook found him there and said nothing.

But she smiled the way people smile when they have been waiting for something and it has, at last, arrived.