Hanseol had walked the three lines alone for three hundred and eleven winters, and on the second morning of Closing Winter he discovered that he was no longer walking them alone.

He knew it at the first cairn. He did not hear footsteps, because the snow swallowed them, and he did not see anyone, because he did not turn around. He simply felt it, a faint warmth at the edge of his awareness, a small bright coal moving at a respectful distance behind him. Every time he stopped, it stopped. Every time he started, it followed. It was like having a lantern set down on the path forty paces back.

He ignored it for as long as he could, which was until the second iron pole.

"Ryu Seoha," he said, without turning.

There was a scuffle, and a small clatter of snow falling from somewhere, and then a cheerful, breathless voice. "I'm at a perfectly safe distance. I measured it. Forty paces. You said the first lesson of the day was I should stay out of your way, and I took that very seriously."

"I did not say that."

"You said I should not break anything. I'm not breaking anything. I'm walking."

"You are following."

"I'm following in an unbroken manner." A pause. "I wanted to see what you do."

Hanseol shut his eyes for a moment. The frost along his sleeves thickened. Behind him, the little coal of warmth waited, hopeful, entirely unabashed, and somewhere in the cold interior of his chest, something he had put away long ago stirred once and turned over.

He turned around.

Seoha stood forty paces back, precisely, bundled in the gray cloak with its hood half down, his dark hair full of snow. In daylight his cheeks had a faint flush that did not belong on a mountain, and there was a smudge of soot on his nose from the kitchen stove, which he had apparently been trying to coax back into life. He had a pouch hanging at his chest, small and worn and tied shut with a leather cord. He was smiling, a quick crooked smile that did not quite reach as far as his eyes, and his hands were tucked carefully inside his sleeves, as if he had resolved to keep them there for the duration of the world.

"Come here," said Hanseol.

Seoha came, covering the forty paces in what was clearly meant to be a dignified stroll and was in fact a half-jog. He stopped well out of arm's reach. Hanseol noted that. He noted, too, that some small, foolish part of him registered the distance as a loss.

"I said I would tell you the rules." He kept his voice level. "There are three. You will hear all of them before you speak."

"I won't say anything."

"You are already speaking."

Seoha pressed his lips together, with great visible effort. Hanseol looked at the sky, which was a hard pale blue, and counted to three.

"The first rule," he said, "is that you do not touch me."

Seoha's eyebrows rose, but he said nothing.

"Not my hands, not my sleeves, not my hair, not my person. Whatever you do in the valley is your affair. Here, it is a law of the Gate. My body is cold enough to stop your heart, and the more you warm it, the worse it becomes for both of us." That was true, as far as it went. It did not go anywhere near far enough. He did not say: and your warmth is more dangerous to me than my cold is to you. He did not say that he had never in his life been less certain what would happen if someone touched him.

"The second rule is the lines." He gestured toward the crescent of gray pillars visible at the far end of the slope. "There are three boundaries. Cairns, poles, pillars. You may walk within the first and the second as you please. You will never pass the third. Not for any reason. Not if you drop something. Not if the sky falls."

"What's past the third?"

"The Gate."

"And the third rule?"

Hanseol hesitated for the barest instant. It was a small hesitation, a flaw in the glass, and he saw Seoha see it.

"You will not enter the Gate Hall," he said. "Nor the sealed hall at the end of the north wing. Nor will you try to open it, or read what is written on it, or ask me what it holds."

There was a pause. It was a short one, and Seoha filled it with a smile so gentle and agreeable that Hanseol would have sworn nothing had happened. But he had noticed the quick catch in the young man's breath, the tiny pause between one blink and the next, like a man who has been given a gift and a warning in the same hand. He filed it away with the other small things he was beginning to notice and did not want to.

"Those are the rules," said Hanseol. "Do you understand them?"

"Perfectly." Seoha tilted his head. "May I try the first one?"

"What?"

"The first rule. Right now." He took a single, deliberate step backward and pulled a small object out of his sleeve. "I'd like to see if I can follow it for an entire day. And to do that, I should really test it."

It took Hanseol a moment to see what he was holding. A seed. A single brown, wrinkled seed, no larger than a grain of barley, balanced on the tip of one bare finger.

"What are you doing?"

"Science."

Before Hanseol could speak, Seoha flicked his wrist, and the seed arced up through the bright air and landed, with a faint tick, on the stone between two of the iron poles of the second line.

Nothing happened.

Hanseol stared at the small dark spot in the snow. Seoha stared at it too. The silence stretched.

Then, from the seed, a fine green thread unwound upward, and the snow around it sank, and a tiny spiral of leaves opened to the sun. It rose a handsbreadth, two, and a single yellow flower budded at its tip. It trembled in the freezing wind, shocked and shining, and the frost on the iron pole beside it began to creep down toward its base.

"Stop that," said Hanseol.

"I didn't do anything. The seed did it."

"You threw a seed over a line I forbade you to cross."

"You said I shouldn't cross it. I stayed back here. The seed is a separate party." Seoha gestured airily at the flower, which, for its part, had curled slightly toward the sun like a small hopeful child. "I think we can agree the experiment was a success. Rules are fine. I just wanted to see how the world behaves with them."

Something went through Hanseol then, hot and white and entirely unauthorized. He told himself it was anger. He had a great deal of anger available, three centuries of it, banked and orderly. It rose without difficulty to the surface and spread across the snow in a sweep of frost so fast that the ground cracked.

The little flower stiffened, and shivered, and turned the color of ice.

"That," said Hanseol, coldly, "is what happens when something grows in this place."

He saw it land. He saw Seoha's smile slip, and not return, and the bright color drain a little out of his face, and he knew at once that he had done something unpardonable and could not say why. The air between them was full of splintered glitter. Seoha looked at the frozen flower, and his hands went back up into his sleeves, quickly, as though he had been burned.

"Right," he said, very quietly. "That's fair."

He turned away. The snow squeaked under his boot. He took one careful step and a second, a third, and Hanseol, who had been about to say something, a word, he did not know what, watched the heel of that boot come down on the glazed patch of ice that his own anger had spread across the path.

Seoha's foot went out from under him.

It happened with terrible slowness. He lurched, arms flailing, hands flung out of his sleeves, the gray cloak flaring, and began to fall backward toward a drop that was nothing at all, a gentle slope, a yard of rock, and Hanseol moved. He did not decide to. He did not think. His body, which had been taught for three hundred years never to reach for anything, simply reached.

His hand closed around the young man's wrist.

It was only a sleeve. He had that much sense. In the instant before contact he had snatched his cuff down over his palm, so that what held Seoha up was a fold of thick silver silk. But the silk could not hold back what was under it. Heat came through it like a river through a thin sheet of ice. It went into his fingers, his palm, the bones of his wrist, and spread up the long line of his arm in a rush that was nearly unbearable. His knees went weak. The frost on his sleeve began to hiss.

For a moment neither of them moved.

Seoha hung there, half-fallen, one hand still caught in Hanseol's grip, face turned up, startled, color flooding back into his cheeks. His pulse beat against Hanseol's fingers, hard and quick and alive. Snow drifted down onto his hair. His lips were parted. Hanseol could see, very clearly, the line of his lashes, and the tiny gold flecks in his dark eyes, and a drop of melted snow gathering on the tip of his nose.

Do not look at him, Hanseol told himself. It did not work.

"Sentinel," said Seoha, softly. "You touched me."

"I did not."

"There's a sleeve involved. I'll allow that. But it still counts."

"It does not count."

"I think it counts." Seoha's voice had a shake in it, a wobble that might have been laughter or something else. "It's your first rule. You broke it in under a day. I'm going to put it on a ledger."

Hanseol let go.

It was like putting down something that burned. He stepped back, pulled the sleeve up over his knuckles, and pressed his fist to his side, hard, as if to hold the warmth in. It stayed in him anyway. It sat in his arm like a coal.

Seoha straightened slowly, brushing snow from the cloak. He did not rub his wrist, though Hanseol saw him want to. He looked at the cracked ice, and at the frozen flower, and finally at Hanseol, and his expression changed. The laughter went out of it. What was left was something more careful and, in a way, more naked.

"I'm sorry about the seed," he said. "Truly. It was a stupid thing to do. I thought if I could make you angry, at least you'd be, it'd be something. It's so quiet here."

Hanseol did not know what to say to that. In three centuries no one had told him anything remotely like it.

"I'll make you a bargain," Seoha went on, before the silence could close over. "I'll keep every rule. All three. I'll stay out of your way, I won't go past the pillars, I won't touch you, I won't go near the sealed hall." He did not quite meet Hanseol's eyes on the last one. "And in return, you'll let me make dinner. And you'll eat it with me."

"I do not eat."

"Everyone eats."

"I do not."

"Then you can watch." Seoha shrugged, as though it were nothing. "That's all. Every evening, at the hour of the bell, or whatever you keep. You sit at the table and I put food on it, and you can look at it and not touch it for all I care. But you sit."

Hanseol stared at him. It was a ridiculous proposal. It was absurd, and sentimental, and everything in him that was made of rules rose up to refuse it at once. He had spent three hundred years eating alone, standing at the stove, in the dark, one bowl of barley every few days, quickly and without pleasure, the way a man feeds a fire. He had spent his entire existence arranging to need no one's company. The idea of sitting at a table across from another living person was so foreign that it did not even hurt.

He opened his mouth to say no.

"Please," said Seoha, in a small voice. "It's only dinner."

The word was a stone dropped into very still water.

"Do what you like with the stove," said Hanseol, and heard how it sounded the instant it left his mouth, and turned on his heel and walked up the slope. Behind him, there was a long silence. Then a quick, astonished laugh, and the sound of running feet on the snow. He did not look back.

The rest of the patrol was torture. He went through the motions, touching each pole, adjusting each cairn, but his attention was elsewhere, caught like a fish in a net. He could feel the young man behind him still, forty paces back, then thirty, then twenty, closing in by degrees, as though his body had not been told it was supposed to keep its distance. Twice Hanseol heard him humming, tuneless, under his breath. Once he heard him ask, to no one, whether pine needles could be eaten.

Near the last of the cairns, Seoha's courage returned in full. "Those lanterns," he called, from twenty paces. "Along the path to the pillars. They were lit the night I came. Are they always?"

"No."

"Who lights them?"

Hanseol kept walking. "Nobody."

"That seems unlikely."

"I did not light them." The words came out of him oddly, as if he were hearing them for the first time. "They have not burned in three hundred years. They burned that night. I do not know why."

Seoha was quiet for the span of ten steps. When he spoke again, it was in the careful voice a person uses near something sleeping. "Maybe they were lit for me."

It was a foolish idea. It was a boy's idea, sweet and self-centered, and Hanseol opened his mouth to say so. What came out instead was nothing, and in the nothing, the frost that coated the lantern posts along the path seemed to glitter a little brighter, as though the mountain, too, were holding very still to hear the answer.

At the pillars Seoha stopped where he had been told to, a dutiful ten paces short, and tilted his head at the single line cut into the face of the nearest stone. The characters were old and angular, worn nearly smooth. "That's not writing I know."

"It is the Gate Law."

"What does it say?"

Hanseol looked at the line. He could read it as easily as his own hand. He had been reading it, every morning, for three hundred and eleven years. "That those who fall before the line belong to the mountain's judgment," he said. "That no one may pass the third pillar uninvited."

"That's all?"

"That is what it says."

It was not all. There were four more characters at the end of the line, crowded close, smaller than the rest, carved by a different and a gentler hand. He had not allowed himself to read them in a very long time. He had taught himself to see the stone and the shape and not the meaning, the way a man learns to walk past a door in his own house. He felt the young man's eyes on the side of his face, curious, patient, warm, and he turned toward the slope and kept walking, and did not look at the last four characters, and did not say that he had not.

By the time the patrol ended, the sun had gone to the far side of the ridge, and the sky had turned the color of a bruised plum. At the foot of the Gate Hall steps, Seoha stopped, and bowed, with exaggerated gravity, as if he were seeing off a magistrate. "Until dinner," he said. "I promise it will be edible."

Then he was gone, into the long dark mouth of the east wing, and Hanseol stood alone in the dusk with the snow settling around him, and the arch of the Gate rising pale and enormous at his back.

He did not turn to look at it. He did not need to.

Later, when the first star had come out, he went back to the small cold room behind the Gate Hall where he kept his things, which was to say nothing. A bare floor. A bedroll he never used. A lamp that had been out for decades. He sat down on the floor, in the dark, and drew his right hand out of his sleeve, and held it in front of his face.

There was something in his palm.

He did not understand at first. It was a drop of water, small and round and perfectly clear, trembling in the hollow of his hand. For one dizzy second he thought he was imagining it. Water. Moisture. Warmth enough to melt a single flake of snow. In three hundred years nothing had melted on his body. Rain froze on his shoulders. Tears, when he had had them, had frozen to his cheeks. He was cold all the way through, a vessel made for one purpose.

And yet the drop sat in his palm, bright and shaking, as though it were alive.

He watched it for a long time. It did not fall. It did not evaporate. It only held there, quivering faintly, with the light of the single star caught in it like a tiny captured sun.

Then, slowly, the cold in him reasserted itself. The edges of the drop clouded. It crystallized, delicately, from the outside in, ice branching across its surface in long fine lines. When it had finished, it was no longer a drop. It was a tiny thing, perfect and translucent, the size of a thumbnail, shaped, unmistakably, like a petal.

Hanseol closed his fingers around it. He pressed his fist against his chest, where there was no heartbeat, and sat very still in the dark.

He ought to throw it away. He knew that. The right thing, the only thing, was to open the door and fling it into the snow, and then go and stand at the Gate until the strange ache in his hand went away. That was the rule. He had never in his life broken a rule that mattered.

Instead, carefully, as if it were made of something that could break, he slipped the frozen petal into the fold of his sleeve, against his wrist, where the warmth of the other young man's skin had lingered. And then, to his own horror, he realized that he was listening, from the far end of the long dark shrine, for the sound of someone setting a table.