The roof of Hollowbrook House was flat, tarred, and edged with a knee-high parapet of crumbling brick, and on Tuesday night it belonged entirely to Alan Frost and a thin cold wind.

He had been resting all day. That had been Valeria's order, delivered at dawn through the cold, closed door that now stood between them, and delivered by proxy, since Valeria herself had not spoken a single word to him since the Hall of Demonstration. It had come instead from Priscilla, who relayed it with great and scrupulous neutrality, in the tone of a diplomat carrying a message between two nations at war. -- Valeria says that you are to rest, -- she had said. -- She says that this is not a conversation. She also says that she is not angry. I believe that she is lying, but I thought it best not to say so.

So he had rested. He had slept until noon. He had eaten three meals, which had made Tobias weep with joy. And now, with the dormitory dark and the town below thinned to a scatter of lamps, he stood at the center of the roof with his hands at his sides, a little pale, a little lonely, and thoroughly determined to get this right.

-- I would like to ask a favor, -- he said quietly, to the empty night. -- It is a small one. I would like to practice the sync. Properly. Alone, with one person, under supervision. I would like to learn how to hold a borrowed skill without it, without it getting away from me, the way it did on Saturday. -- He paused. -- It would help if the rest of you would give us a little privacy. For the drill. It is not that I do not trust you. It is only that I would like to make mistakes without an audience.

There was a pause.

-- I shall chart the lunar tide instead, -- said Priscilla, in a curiously subdued voice. -- Quite happily. I have a great deal to chart. -- A small, odd hesitation. -- You may close the window, Alan. I will not look.

-- I am asleep, -- said Helga, immediately. -- Snoring. Do not wake me.

-- Valeria has already closed hers, -- said Seraphina, softly. -- Though I do not know that it was a courtesy. -- A longer pause. -- I will leave a very small crack, dear. A hair. So that if something goes wrong, I might, so that I might. You will not feel it. I promise. I will not look.

-- Thank you, Senior Seraphina.

-- Do not thank me, -- she said, very gently, and the window narrowed, but did not shut. -- I am only doing what you asked. As best I can.

He felt the pressure change. One by one the warm presences thinned and drew back. It was easier this time, a little less like stepping into a cold hall. Four of them were still there, behind their closed panes, like people in the next room with their ears carefully turned away. Only one remained at the front of his awareness, close and bright and clear, as steady as a lamp on a table.

-- Hello, kid, -- said Nyx.

She came out without being summoned. He had asked her, in the dark of the afternoon, whether she would be willing to stand as his partner in the drill, and she had said yes in an odd, light, careful voice, and told him to leave the manifestation to her. It cost him four points to open the door, and a further trickle to hold it, and she was simply there at the edge of the parapet, one leg dangling, sitting in the dark with a candy in her cheek.

-- You did not need to climb, -- said Alan. -- I was going to call you.

-- I know. I like to arrive before I am invited. It is a professional habit. -- She tipped her chin toward the roof. -- All right. What are we practicing?

-- Holding. I can start a sync, and I can name a skill. What I cannot yet do is hold it steadily, or end it cleanly. On Saturday it ran out of control. I would like to learn the edges.

-- That is a very sensible request for a boy who nearly died in an alley.

-- I would prefer not to repeat it.

-- Good. -- She slid off the parapet and landed lightly on the tar. -- The rule is, one skill at a time. The skill is mine. The footwork, the low step, the weight shift. You borrowed it this morning in the Hall and made a very pretty fool of that wolf-boy, so we know you can hold it for about four minutes. Tonight, we go for ten. You name it, you hold it, you walk the length of the roof and back without once looking at your feet. If it slips, you tell me, and I take it back. If it hurts, you say halt. Do you understand?

-- I understand.

-- And remember the rest of the deal. -- She stepped closer, and the amber of her eyes caught the faint starlight. -- Backlash is split. Half to you, half to me. That is the covenant. I will feel what you feel. That is the safeguard. So if you feel something you do not like, I will, too, and there is no point being brave about it. I would rather you were honest. Agreed?

-- Agreed.

-- Say it properly.

-- Article Six, -- said Alan. -- Nyx's footwork. One skill. Beginning now.

The change came like a breath of cold air. His weight slid forward onto the balls of his feet. His shoulders loosened. His steps shortened, lightened, softened, and when he put a foot down on the tar, it made no sound at all. He began to walk, slowly, along the length of the roof, with his hands loose and his eyes on the lit window of the library tower across the grounds, and the borrowed motion flowed through him like a stream through a worn channel.

-- Not bad, -- said Nyx, pacing a few feet behind him, as noiseless as he was. -- Hips lower. Chin down. You are walking like a clerk who has been told there is a ghost behind him. Good. Keep going. You do it very well.

-- I am not sure that is a compliment.

-- It is the best one I have.

The sync held. They reached the end of the roof, turned, and started back. The wind brushed his hair. The stars were very bright. For several minutes it was almost pleasant, like a long night walk in a quiet town, and he began to relax.

It was somewhere past the seventh minute that the ache began.

It started in his calves. A thin, bright cramp, small and sharp, as though a wire had been pulled taut inside the muscle. He did not stop walking. The pain climbed, tightening through both legs, into the backs of his knees, and he gritted his teeth and kept his eyes on the library tower. It was only the sync, he told himself. It was only the price. It would pass.

And beside him, he heard a very small, very brief intake of breath.

It was quite faint. It was the sound of someone biting down on something. When he glanced sideways, Nyx's face was perfectly composed, her smile in place, and she was walking in step with him as lightly as ever. But her left hand had curled very slightly at her side, and she had put a little more weight on her right foot.

-- You felt that, -- he said.

-- Nothing at all, -- said Nyx, easily. -- I have the feet of a cat.

-- Your calves.

-- Perfect. Excellent. Never better.

-- It hurts you.

-- It is half, kid. -- She did not look at him. -- That is the deal. It is not bad. It is only a cramp. I have had worse from sitting on a wall.

He walked another three steps, in silence, with the pain pulling in his own legs. He knew how it worked. Half to each. It was fair. It was the arrangement they had all agreed upon. He had made it himself, sitting on a laundry list in the dark, and he had been proud of it.

And yet he could feel the shape of her half, pressing against the edge of his own, a small cold bright thing like a splinter. He could feel exactly where it sat. And he knew, because he had discovered it by accident in the alley on Saturday, with the ring warm on his finger and the world going grey, that there was something in his chest that would take it.

It was easy. That was the worst of it. The hollow beneath his ribs opened, just a little, like a mouth, and the pain went toward it. It did not feel like theft. It felt like water finding the lowest place. He did not say anything. He did not even look at her. He simply let it flow, and the splinter slid out of the edge of her half and into his, and the pain in his legs doubled, and he did not let it show on his face for even an instant.

Beside him, Nyx stopped walking.

-- Hm, -- she said.

She stood very still on the tar, one hand curled at her side. She flexed it. She rolled her ankle. She shifted her weight from one foot to the other, with the slow, careful attention of a person testing ice.

-- It is gone, -- she said.

-- What is gone?

-- The cramp. -- She turned her head, and the amber of her eyes was suddenly very bright and very sharp. -- It was there. It was exactly there. And then it was not. It went, like a hand being lifted. -- A pause. -- Alan.

-- It is probably the cool air, -- he said. -- A transient muscular...

-- Stop the sync.

-- I am not finished with the, ah, the full ten...

-- Stop it. Now.

He let it go. The borrowed lightness drained out of his stance, and the pain, his own pain, doubled, redoubled, unattenuated, hit him all at once. His calves locked. His knees buckled. He caught himself on the edge of the parapet and hung there, gripping the brick, breathing in small hard gasps through his teeth.

Nyx was in front of him before he had finished falling.

-- Look at me, -- she said.

He looked. She was crouching on the tar with her hands on her knees, and her face was not teasing, and not laughing, and not anything he had seen on her before. It was bare, and still, and very intent.

-- You took it, -- she said.

-- I do not know what you mean.

-- You took my half. You pulled it into your own. I felt it go. It went toward your chest, like a thread through a needle. -- Her voice was quite level. -- I have been in a thousand fights, kid. I know what it feels like to be hurt. I know exactly what it feels like when somebody takes it away. How long have you been doing it?

-- I have not been doing anything.

-- Your cuff.

-- I beg your pardon?

-- Your cuff. -- She nodded at his wrist. -- You have been adjusting it for the last ten seconds. It is perfectly straight. You are smoothing the same inch of cloth. And your ears are not red. -- A very small pause. -- Not even a little. When you are caught out, you do not blush. You arrange things.

Alan looked at his hand. It was smoothing his sleeve. He stopped it.

-- It was a safety measure, -- he said, in the flat even voice that came to him whenever the floor began to tilt. -- The covenant stipulates that backlash is divided equally. I observed that a portion of the load was being transferred to you. As the borrower, I felt it was appropriate to bear it. It is a perfectly reasonable allocation. The terms are unaffected.

-- It is not a reasonable allocation.

-- The Agreement does not specify a prohibition on voluntary absorption.

-- Article Five, -- said Nyx.

He stopped.

-- Article Five, -- said Nyx, quietly. -- Nobody harms anyone in this agreement. Including you. You wrote it. You put it in yourself, in your own handwriting. I remember. I have a very good memory. Including me, you said. And then you went and did exactly what you wrote it to prevent.

It was a very precise piece of reasoning. It was a trap, and he had walked into it, and he had no reply at all.

-- I was not harming myself, -- he said at last. -- It was a transfer. A routine one. It is within my capacity, and the cost is acceptable. I judged the trade to be favorable, on balance, to the group.

-- On balance, -- said Nyx.

-- Yes.

-- You are shaking, you know.

-- It is the cold.

-- It is a very nice roof, and a very warm night. -- She sat down on the tar in front of him, cross-legged, and put her chin on her fist. For a while she did not speak. The wind pulled at her cloak. A bell somewhere struck the hour, thin and far away. -- Why? -- she said at last, very softly. -- Not the numbers. The why.

He opened his mouth to answer. He had an answer ready. It was clean, plausible, and tidy, and it was about efficiency, and it was entirely false.

What came out instead was something else.

-- I would rather carry it than owe it, -- said Alan.

The words hung in the cold air like breath.

He had not meant to say them. They had come up from somewhere low and old, a place he did not often visit, and now that they were out, he could not take them back. He stared at the tar between his knees.

-- In the house I grew up in, -- he said, quite slowly, in a voice that did not sound like his own, -- people kept ledgers. Of what you owed. Every meal, every candle, every bar of soap. They wrote it all down. There was a little book in the kitchen, and a pen on a string, and every night, someone would sit down and add up the cost of me. And then in the morning they would tell me what it was. -- He swallowed. -- It was never very much. It was always more than I could pay.

Nyx said nothing at all.

-- I learned that a thing you carry yourself does not go in the book, -- said Alan. -- If it hurts and I do not tell anyone, it is mine. Nobody can charge me for it. It is, ah. It is a very clean kind of ownership. I did not realize I was doing it on purpose. I only noticed that when I took it, it stopped being a debt.

-- Alan, -- said Nyx.

-- It is a bad habit. I know. I am aware that it is irrational. I just. -- He stopped. -- It is the only way I know how to be safe.

The roof was very quiet. Nyx sat with her knees drawn up and her chin on her arms, looking at him, and her face was bare and grave and strange in the starlight. The grin was gone entirely. There was no mockery in her at all. For what felt like a very long time, she said nothing, and he found that he was grateful.

-- Right, -- she said at last. -- That is the first true thing you have said to me.

-- I say true things.

-- You say accurate things. It is different. -- She straightened her back. -- Listen to me, kid. I am going to tell you something, and I am only going to say it once, and you are going to remember it.

-- Yes, Senior.

-- Do not call me that tonight.

-- ... Nyx.

-- Better. -- A small flicker of something that was almost a smile. -- A debt is not a chain.

-- I am not sure I...

-- A debt is a thing you can pay. It has a size. It has an end. A chain does not. A chain is when someone tells you that you owe, and will not tell you how much, and will not let you pay. That is what they did to you. That is what is in the book. That is not what this is. -- She raised a hand and tapped, very lightly, on her own breastbone. -- What we are, in here, is not a ledger. I did not give you half of my pain as a loan. I gave it to you because that is how the thing is built. It is not a cost. It is just a share.

-- It is still pain.

-- Yes. It is a share of pain. That is called company. -- She said it very flatly. -- It is not nice, but it is not a debt, and when you take it away from me in secret, you are not paying for anything. You are taking something from me. You are deciding, without asking, that I cannot carry my own half. Do you know what that is called?

-- ... Paternalism.

-- I was going to say theft, but yours is better. -- A small crooked smile. -- It is a kind of insult. And the worst part is that you do not even know you are doing it.

He sat very still. A small cold hum went through the ring on his finger.

-- I did not mean it as an insult, -- he said.

-- I know. That is why I am not angry. -- She held up a hand. -- But you will do two things for me.

-- Anything.

-- Do not say anything. Listen first. -- She counted on her fingers. -- One. You will tell me before you do it. Every time. One word is enough. Say take, or share, or I am going to pull. If I say no, you do not. If I say yes, you do. That is the whole rule. You do not do it in the dark. Two. If it hurts, you say halt. You do not carry it. You do not smile. You say halt, and we stop, and I sit with you until it is over. -- Her voice dropped. -- Do you understand? It is not a punishment. It is not a debt. It is a thing we do. That is all.

-- I understand.

-- Say it.

-- I will tell you before. And I will say halt if it hurts.

-- Good.

He let out a breath. It shuddered, and he was ashamed of that, but she did not mention it.

-- There is one more thing, -- said Alan. -- I would like to ask a favor.

-- You are very bold tonight.

-- I would like you not to tell Senior Seraphina.

Nyx raised her eyebrows.

-- Not yet, -- said Alan quickly. -- I only need time. I would like to learn to do it differently first. If she knew that I had been, ah, absorbing, she would be, she would, I think it would be very hard for her. It would feel to her like a failure. And I think she would, she would try to stop me. In the way that, ah, in the way she does. I would like to be able to tell her myself, when I know how.

-- Hm. -- Nyx considered this for a long time. -- It is a bad idea.

-- I know.

-- It is a very bad idea. -- She tapped her thumb against her knee. -- I will keep it. For now. On one condition. If you faint again, if you so much as sway, I will tell her, and I will not ask permission, and I will enjoy her face. Agreed?

-- Agreed.

-- And if I find out you have done it again without telling me, I will tell her anyway.

-- That is fair.

-- It is extremely fair. -- She stood up, brushed off her knees, and held out a hand. -- Come on. Up. Your legs have stopped working. I can see them thinking about it.

He took her hand. It was warm, and rough, and exactly strong enough, and she pulled him to his feet in one smooth motion, and let go at once. His calves screamed. He swayed. She caught his elbow, briefly, without comment, and then released it as soon as he was steady.

-- Walk, -- she said. -- Slowly. Down the stair. Straight to bed. I am going to follow you, and if you fall, I am going to laugh.

-- That seems an excessive reaction.

-- It is a very good laugh. -- Her voice was warm. -- Go on.

They went down together through the dark house, past the sleeping rooms, along the narrow creaking corridor. Nyx walked behind him in perfect silence, and he did not fall, and she did not laugh, and when they reached the door of the dormitory, she paused with one hand on the frame.

-- Alan, -- she said.

-- Yes?

-- I am not good at this. -- It was very low, and it was very quick. -- I want you to know that. I make jokes. It is what I do. I have spent a thousand years making jokes so that nobody would look at me closely. But I looked at you, tonight. And I will not make a joke about it.

He did not know what to say. He did not have a word for it.

-- Thank you, -- he said.

-- Do not thank me. Eat your candy.

She pressed something small into his palm. He looked down. It was a boiled sweet, striped red and white. When he looked up, the corridor was empty.

-- That was nicely done, -- said Priscilla's drawl, faint and very kind, from the other side of her window.

-- You said you would not look.

-- I did not look. -- A pause. -- I heard. The glass is thin.

-- That is not what you promised.

-- No, -- said Priscilla. -- But it is what I did. -- She hesitated, and her voice dropped. -- You were very brave, Alan. I would not want you to think otherwise.

He did not answer. He slipped into his bed, and pulled up the blanket, and lay on his back, with the sweet in his fist, and the ache in his legs a slow warm throb.

Somewhere on the far side of the dark, a very soft voice said, in a tone so quiet that it might have been his imagination:

-- Goodnight, dear. Sleep well.

It was Seraphina. She was smiling. He could hear it. And as he drifted toward sleep, with a small cold prickle at the back of his neck, he found himself wondering how wide, exactly, a hair could be.