The moon was nearly full, and Alan could not sleep.

It had been building all week, a restlessness under his ribs that he had been blaming on exercise, and tea, and the general upheaval of having five extra people living in his head. But on Thursday night, as he climbed the spiral stair of the Old Clock Tower with his boots in his hand and the stone cold against his socks, the feeling sharpened into something he could finally identify. It was not anxiety. It was closer to a tuning fork struck somewhere far away. The hollow in his chest ached faintly, like a tooth before rain, and every step he took toward the roof made the ache a little clearer.

-- You are doing the thing with your hand again, -- said Priscilla.

-- Which thing?

-- The sternum. Left side. You have touched it eleven times since dinner. It is an elevated rate.

-- It is a mild ache.

-- It is a lunar resonance, -- said Priscilla, with a pleased, faraway hum. -- I would wager a great deal that your structure responds to the tide of the moon. I will graph it. I will graph it every night.

-- You will not graph it every night.

-- I will graph it every night, -- said Priscilla serenely, and he could hear her settling deeper into the cushions of the Lobby, wherever they were.

The door at the top of the stair stood open to the sky. Alan stepped through and onto the roof of the Old Clock Tower, and for a moment he forgot everything else.

The whole academy lay spread beneath him in the moonlight like a map. The towers of Lumina rose in pale silver against a sky so full of stars that it looked sprinkled with salt. The great dome of the Rotunda shone like a pearl. The gardens were patches of dark velvet, and the river wound beyond them, a thread of white light. Wind plucked at his collar, cold and clean. And above it all, a little to the east, the moon hung enormous and nearly round, one edge shaved off by a thin curve of shadow.

-- Beautiful, is it not? -- said a voice behind him. -- You have the look of a man who has never seen a roof.

He turned. A woman was sitting on the stone parapet at the edge of the tower, one leg tucked beneath her and the other swinging idly over a hundred-foot drop. She had not been there a moment before. He was almost sure of it.

Alan had not yet summoned her. She had come out on her own.

-- Senior Nyx, -- he said. -- That is not permitted under Article Two. Unscheduled manifestation requires mutual consent.

-- You consented, -- said Nyx. -- You came up here. You are standing on my roof, in the dark, at the appointed hour, wearing the expression of a man waiting for a ghost. It was implied.

-- It was not stated.

-- Everything is stated if you know where to look. -- She slid off the parapet without a sound and landed on the stone, light as a drop of water. In the moonlight, her skin was warm brown and her eyes were two pools of molten amber, the pupils slits as thin as threads. A cloak of dark cloth hung from her shoulders, and it seemed to swallow the moonlight rather than reflect it. She stood with her weight on the balls of her feet, loose and easy, smiling a small crooked smile. -- Come on, kid. Cost me half the mana to climb up here quietly. You can spend the rest.

-- Technically, it costs me, not you.

-- Tomato, tomahto. -- She waved a hand. -- Three rules for tonight. Rule one. You listen to me, and you do not talk back. Rule two. If anything hurts, you say halt, and I stop. Rule three. No laughing at me.

-- Why would I laugh at you?

-- Because I am about to be very good at something, and you are going to be very bad at it. -- She grinned. -- I would like to establish a baseline of dignity before we start.

She began with traps.

It was a game, she said. A simple one. She would walk the length of the roof, and on the way she would set seven snares, tripwires and pressure plates and a few things she called gifts, and Alan would have to cross the tower from one end to the other without triggering any of them. If he stepped on one, she would know. If he missed one, he would learn something. If he found them all, she would owe him a favor.

-- And if I fail all seven? -- said Alan.

-- Then you owe me a favor, kid. -- Her smile widened. -- It will not be a nice one.

-- I do not like those odds.

-- Nobody does. That is why they are odds.

He failed the first one in four seconds. He took a single step forward onto what looked like an ordinary flagstone, and something went snap beneath his boot, and a small cloth bag fell from the parapet and burst on his head, showering him in fine pale powder. He stood there coughing, blinking, covered in flour.

-- One, -- said Nyx, delighted. -- Flour. I was being kind.

-- That is not a trap, that is an insult.

-- It is both. Try again.

He failed the second one by walking into a thread he had not noticed, stretched at ankle height between two pipes, and fell flat on his face. He failed the third by stepping around the thread, which was exactly what Nyx had expected, and onto a plate that sprayed him with cold water from a concealed hose. The fourth gave him a fright. The fifth made him swear, which he did quietly, and with surprising range. By the sixth, he was soaked, powdered, and thoroughly humbled, and Nyx was lying on her back on the parapet with her hands behind her head and tears of laughter in the corners of her eyes.

-- You are, -- she gasped, -- the worst thief I have ever met.

-- I am not a thief.

-- You are about to be a very bad one. -- She wiped her eyes, still hiccupping. -- All right. All right, kid. I will be fair. Stand there and look at it. Do not move. Just look.

He stood. He looked. And because there was nothing else to do, and because he was wet, and tired, and had begun to feel the first faint stirrings of stubbornness, he did what he had done all his life when he did not understand a problem. He took it apart.

The roof was a rectangle of stone. The flagstones were laid in rows. He studied the dust. There was a fine grey film over the whole surface, undisturbed by any footprint but his own, and Nyx's. He noticed the pattern of her footsteps, and he noticed that on the way across, they did not run in a line. They curved. They curved around a spot near the east parapet, and then they curved again near the pipes. The wind had been blowing from the west all evening, and a few dead leaves had collected against the base of the tower wall. They had collected in a neat little drift. And in the drift, there was a single leaf lying very slightly differently from the rest, as though something had lifted it and set it back down.

He stepped sideways. He stepped over a stone that looked perfectly ordinary. He walked in a narrow curve around the east side, with his head down, watching the dust, and he stopped three feet from the pipes, and crouched, and put out one finger and lifted a thread so thin that he had to tilt it toward the moon to see it at all.

Nyx stopped laughing.

-- That is the seventh, -- he said. -- I think. There is a plate under the third flagstone from the corner. There is a thread beneath the pipe. And, ah, I believe the water hose is the one by the chimney. I am not certain about the second. Was that the one with the bell?

Nyx had sat up.

She was staring at him. The moonlight lay across her face, and for the first time that evening there was no grin on it at all. Her amber eyes had gone narrow and bright, and she looked at him the way a cat looks at a bird that has just done something a bird should not be able to do.

-- How, -- she said slowly, -- did you find them?

-- I looked at the dust, -- said Alan. -- And the leaves. And you walked around them. You stepped in a curve, and you do not curve for no reason. -- He paused. -- It was not very difficult. Most people stop looking when they get frightened. I was already frightened, so I looked more.

For a long moment, nobody said anything.

-- Huh, -- said Nyx.

It was a very small sound. It was the sound of a person rearranging something in her head. Then, slowly, the grin came back, but it was a different grin, quieter, almost private.

-- You learn with your eyes, -- she said. -- Not your hands. That is rare. Most people have to be burned first.

-- I have been burned, -- said Alan. -- I would prefer not to repeat the experience.

-- ... Yes, -- said Nyx, and for a second the lightness went out of her voice entirely. -- I suppose you have.

She pushed herself off the parapet and walked toward him, and the lightness returned in her stride. She stopped a few feet away and cocked her head, her short plum-colored hair stirring in the wind.

-- All right. You have earned a favor. What do you want?

-- I would like, -- said Alan, -- for you to stop calling me Red.

-- Denied. That is not a favor, that is a miracle. Try again.

-- Then I would like to ask a question. -- He hesitated. -- Why do you teach this? Traps. Tricks. Escaping. It seems a strange thing to want a stranger to know.

Nyx looked at him a moment longer. She tucked a stray curl behind her ear.

-- Because, -- she said, with great lightness, -- the dead are very bad at running, kid. It is the one thing I know for certain.

She said it as a joke. It did not sound like one.

-- Next lesson, -- she continued briskly. -- I will show you how a thief takes a pocket. And then, because I am generous, I will show you how a thief takes a diploma.

-- What does that mean?

-- It means we are going to talk about cheating on your theory exam.

-- No.

-- You have not heard what I am offering.

-- I have no wish to hear it. I do not cheat.

-- It is not cheating. It is information management. There is a very easy way to read answers from the instructor's desk during the proctoring, if you stand at a certain angle, and I have been studying the room...

-- No, Senior Nyx.

-- It would take me an afternoon.

-- I am not going to cheat.

-- Why not? -- said Nyx, honestly curious. -- Everyone does. The whole world is cheating, kid. It is a matter of scale. The ones who get caught are the ones who are bad at it. I could make you very good.

-- Because if I am caught, -- said Alan, -- I will be a boy with a record. A boy with a record will be examined. And a boy who is examined will be noticed. And if he is noticed, then, ah. -- He swallowed. -- Then people will look at his family.

There was a silence.

-- I agree with the boy, -- said Valeria, unexpectedly, from the depths of the Lobby.

-- Oh, no, -- groaned Nyx. -- No, no, do not side with the swordswoman. Not tonight. I was winning.

-- You were not winning. You were corrupting a minor.

-- He is eighteen!

-- He is a student. The principle holds. -- A short satisfied sniff. -- A man who is honest in small things can be trusted in large ones. I have seen what becomes of the other kind.

-- I am going to put a thread across your door, -- said Nyx darkly, to the sky. -- A very thin one.

-- I do not sleep, -- said Valeria. -- I am in a soul. -- A pause. -- It would not work.

-- I will find a way.

Alan, standing wet and powdery on a rooftop under a nearly full moon, felt the corner of his mouth lift in a helpless smile. It was the first time he had been able to laugh at the whole absurd arrangement. It was a small thing. It felt very large.

-- All right, -- said Nyx, still grumbling. -- Fine. No cheating. I will respect it. But you are going to learn to get out of a hold. If somebody grabs you from behind in a dark corridor, you are not going to apologize to him, kid. You are going to break his nose. Do you understand?

-- I would prefer to reason with him.

-- No. You would prefer to be alive. Come here.

He walked over, and she turned him by the shoulder, gently, until his back was to her. She stood very close. He could feel the warmth of her at his shoulder blades, and smell something faintly spicy, like cloves and cold iron. She did not touch him.

-- I am going to demonstrate, -- she said. Her voice had dropped, low and a little rough, no longer teasing. -- I am going to put my arms around you from behind, the way an attacker would. I will not squeeze. I will hold you lightly, so you can feel the shape of it, and then I will show you three ways out. Is that all right?

-- Yes.

-- I will say it again. If it is not all right, at any point, say halt, and I let go. No questions asked. Do you understand?

-- I understand, Senior.

-- Good. Nod.

He nodded.

Her arms came around him slowly. One crossed his chest below the collarbone, the other circled his waist, and her forearms were warm and lean and strong. She rested her chin lightly against the top of his shoulder, and he could feel her breath against the side of his neck. It was a hold, a demonstration, a lesson. It was also, he realized with a slow and horrified rush, an embrace. His heart gave one very loud, very clear beat. He could feel her feeling it through her forearm.

-- Oh, -- said Nyx softly, very close to his ear. -- Hello there.

-- It is... cold up here, -- said Alan.

-- It is a mild evening.

-- It is a rooftop. There is wind.

-- You are quite warm for a cold man. -- He felt her smile against his shoulder. -- Your ears are red. I can see them. I can see them from here, in the moonlight, and they are practically glowing.

-- It is the, ah, the blood flow, -- said Alan, rapidly. -- To the extremities. From the, from the trap exercise. I think we should discuss the schedule. I have a, there is a Friday rotation with Senior Helga that begins at five, and I am not certain I have confirmed the location, and I would prefer to avoid being late. Has anyone checked the workshop key? I believe I need to collect it from the groundskeeper before dawn. And Saturday is open, which is a problem, because I believe the Agreement should be amended to cover...

-- Kid, -- said Nyx, laughing into his shoulder. -- Kid. Breathe.

-- I am breathing.

-- You are talking about keys.

-- It is an important key.

-- It is the most adorable key I have ever heard of. -- She squeezed him, just slightly, and let him go. She stepped back, and he turned, and the cold air rushed in where she had been. Her eyes were shining with delight. -- All right. That was the soft version. That was the warm-up. Now I am going to show you what it feels like when it is not a lesson.

-- Is that necessary?

-- Yes. You need to know what panic feels like in the body, before you meet it. Otherwise you will freeze. -- Her voice was lighter, but she did not smile. -- Say halt if you want me to stop. I will stop. I mean it, Alan. Do you understand?

It was the first time she had used his name. He looked at her in the moonlight, and for a moment he thought he saw something very careful in her face, something that was watching him much more closely than her voice let on.

-- I understand, -- he said.

-- Nod.

He nodded.

She stepped behind him again. This time her arms closed around him quickly, without ceremony, one forearm locked hard across his chest and the other clamped around his upper arms, pinning them against his sides. She pulled him back against her and lifted him slightly, until his heels left the ground. It was fast, and it was strong, and it was nothing like a demonstration.

Alan did not flinch.

He did not struggle. He did not shout. He did not say halt. He simply went completely still, every muscle locked, breath stopped halfway up his throat, his face wiped to blankness. His hands, pinned at his sides, curled into fists so tight that his knuckles went white. The world narrowed to a tiny bright point. Somewhere very far away, he heard the sound of his own heartbeat, hard and fast, like a fist on a locked door. He was ten years old. He was standing in a hallway. A man in grey was holding his shoulders and saying something kindly in a very quiet voice.

The pressure vanished.

Nyx let go so fast that he stumbled forward and caught himself on the parapet. He stood there with his back to her, breathing hard, shoulders rigid, hands braced on the cold stone. For a moment there was no sound on the roof but the wind.

-- Alan, -- said Nyx.

Her voice was very quiet. All the lightness had gone out of it.

-- Alan. Look at me.

He turned, slowly. His face was perfectly composed. He was smiling the polite smile. It was a good smile. It would have deceived anyone.

Nyx was standing six feet away, hands lowered, empty, open. The grin was gone. Her face was bare and sharp and still, and her amber eyes had lost their gleam and gone dark and steady, like a lantern turned low. She did not look amused. She did not look sorry, exactly. She looked like someone who had just stepped on a floorboard in the dark and heard it break.

-- That was not embarrassment, -- she said.

-- I am perfectly all right, Senior Nyx.

-- You did not blush. You did not talk about keys. You did not make a joke. -- Her voice did not rise. -- You went still. You stopped breathing. You stopped being in your body. I have seen that before. I have seen it on people who were not fine at all.

-- It was a demonstration. I was, ah, concentrating.

-- No, you were not. -- She took a step closer, slowly, and stopped. -- Alan. Listen to me. I need you to hear this, and I need you to hear it exactly. When you are not comfortable, you say halt. Not because you are weak. Not because you owe me an explanation. Because that is how this works. That is the entire point of the word. If you go quiet, I will stop, and I will always stop, but I would rather not have to guess. All right?

-- Yes, Senior.

-- I do not joke about that. -- She looked at him, and the amber of her eyes held no humor at all. -- Ever. About that. Understand?

-- I understand.

-- Good. -- She let out a long breath, and some of the tension in her shoulders came down. -- Good. Now sit. You are shaking.

-- I am not...

-- You are shaking. Sit.

He sat on the stone, with his back against the parapet and his knees drawn up, and after a moment, Nyx sat beside him. Not close. A careful yard away, her shoulder not quite touching his. She stared out at the moon-washed towers and said nothing at all, which he was beginning to realize was a rarer and more valuable gift than anything she had given him that night.

The wind moved. A bell rang somewhere in the town, tolling the half hour. Down in the gardens, a night bird gave a single liquid call and fell silent.

-- Thank you, -- said Alan, at last, quietly. He took a breath. -- I owe you for the lesson. I will find a way to repay you. I believe the going rate for private instruction is...

-- Stop, -- said Nyx.

-- I am only...

-- Stop. -- She reached into the pocket of her cloak, and drew out something small and round, wrapped in a twist of colored paper. She held it out on her open palm. -- Here.

He looked at it. It was a boiled sweet, striped red and white.

-- That is tuition, -- said Nyx. -- Do not pay it back.

-- But I...

-- It is a sweet. It is not a debt. You eat it, and you say thank you, and it is finished. That is the whole transaction. -- Her voice was dry and gentle. -- Take it, kid.

He took it. It sat in his palm, small and absurd, a bright scrap of nonsense in the middle of a very long night. He unwrapped it, slowly, and put it in his mouth. It tasted of cherries and burnt sugar and something faintly sharp, like pepper. He sat very still, with his eyes on the moon.

-- Thank you, -- he said.

-- You are welcome, -- said Nyx.

It was a very small exchange, and it ended there. It was one of the strangest and best things that had ever happened to him, and he did not know how to say so, and so he said nothing, and she let him.

Behind them, the moon sank slowly toward the dark line of the western hills. The ache in his chest had settled into a quiet, steady hum. Beside him, a woman who had spent a thousand years in the shadows sat in the moonlight with her knees drawn up and her chin on her arms, looking, for the first time since he had met her, almost young.

The glow around her began to thin. Her cloak frayed at the edges into small drifting motes of dark violet.

-- Time, -- she said. -- I will go, then. Do not forget the key.

-- I will not.

-- And Alan.

-- Yes?

-- You are very good at looking, -- she said softly. -- Do not stop. -- Her smile came back, small and crooked, but real. -- And wear something you can fall down in.

She faded into the night.

He stayed on the roof a while longer, with the sweet melting on his tongue. After a time, a voice cleared its throat, gruff and sleepy and without a shred of subtlety.

-- Friday, -- said Helga. -- Tomorrow. Five o'clock. Sharp. If you are late, I throw the hammer.

-- I will not be late, Senior Helga.

-- You said that about the key.

-- I have not forgotten the key.

-- You will, -- said Helga. -- Five o'clock, boy.

-- Your heart rate peaked at one hundred and forty-two, -- added Priscilla, in a very small, very serious voice, from the far end of the Lobby. -- At the second hold. And dropped to sixty in four seconds. I have never seen a physiological response like it. I would like to discuss it. Tomorrow. Gently.

-- Thank you, Senior Priscilla, -- said Alan, tiredly. -- Perhaps not tomorrow.

-- Then the day after. -- A pause. -- I will wait.

He climbed to his feet and walked toward the stair, and as he reached the door, he glanced back at the moon one last time. It hung huge and pale over the sleeping academy, nearly full, with a thin dark edge still missing. Beneath his ribs, the ring of absence rang very softly, like a bell touched by the wind.

He could not have said what it was calling to. But for the first time in many years, he did not mind the sound.