The fifth day of isolation began with dry fists striking the bamboo door, making the wood crack and cutting the silence of the room.
"Brother-in-law! Sister!" Yù Méi shouted from outside. "It's been four days! The broth has gone cold! You promised to teach me the mine markings, A-Yuǎn! Open up!"
On the bed, Zhì Yuǎn opened his eyes and was about to answer when Yù Qíng's hand closed hard over his mouth. Pressed against his side and staring fixedly at the locked door, she scratched the sheet with her nails and locked her jaw before removing her hand from her husband's mouth to answer alone, her voice hard.
"The stuffy air of the mine nearly dried your brother-in-law's bones, Méi! He's burning with fever and he's staying in bed today. Go home and stop banging on this door!"
Outside, Yù Méi fell silent for a moment.
"But I brought fresh bread!" she protested, kicking the base of the door.
"Eat it on the way," Yù Qíng answered. "The lock stays where it is."
A muffled grumble came from outside, followed by the sound of her footsteps moving away down the path.
Zhì Yuǎn rolled onto his side and braced his weight on his elbow, looking at his wife.
"Fever?" he murmured.
Yù Qíng's jaw relaxed and a hungry smile appeared on her lips as she ran her hands over his nape, pulling her husband's scalding chest against her cold breasts.
"You're always burning for me," she whispered, opening her legs to wrap herself around his waist.
Zhì Yuǎn moved his hips and entered her all at once, drawing a gasp from Yù Qíng as her fingers dug into his hair and the friction began again.
------
Yù Méi descended the bamboo grove path, kicking dry branches out of the way. She gripped the handle of the wicker basket so hard that her knuckles were white, while inside the clay bowl of bone broth still released steam beside the two wheat loaves she had taken from the oven before the sun rose.
When she crossed the courtyard of the main house, the ground was already a mess of dust and shouts. Two porters ran past with pine beams on their shoulders toward the northern slope, and her father's hoarse voice echoed from the mine entrance, demanding more haste with the picks as the army's deadline turned the entire village into a trampled anthill.
Yù Méi entered the open kitchen at the back and slammed the basket onto the wooden counter.
"She didn't even open the door!" the youngest complained, throwing herself onto a low bench and crossing her arms with a pout forming on her sweaty face. "She said brother-in-law has mine fever again and told me to eat the bread on the road!"
Near the stone stove, Sū Huì did not stop kneading the heavy dough. The mother had deep dark circles under her eyes from having spent half the early hours awake preparing extra meals for the miners' doubled shift, but the movement of her hands remained firm and steady.
"And why did you go knocking there so early, Méi?" Sū Huì asked in a calm voice, blowing a strand of gray hair that fell over her sweaty forehead. "I told you to leave the basket on the veranda."
"Because it's been four days since anyone's seen their faces!" Yù Méi braced her elbows on her knees and sank her chin into her hands, sulking. "A-Yuǎn promised to teach me the rest of the weight calculations, but sister locks that shack like someone's going to steal him in the middle of the woods. She doesn't even let him talk to me properly! It seems like brother-in-law is made of sugar and will melt if I get close."
Sū Huì let out a short laugh through her nose, wiped her hands on her flour-stained apron, and took one of the warm loaves from inside the rejected basket, breaking it in half before extending one half to her youngest daughter.
"Eat it before it hardens," the mother said, leaning her hip against the counter. "Your sister has always been like this. You were too young to remember, but on the day your father brought A-Yuǎn carried from the trees, with his head bleeding and not even remembering his own name, Qíng sat on the threshold of that room and didn't leave for three days."
Yù Méi took the bread, chewing a large piece while still sulking.
"I know," the girl murmured, mouth full. "My friends' mothers still say to this day that she looked like a dog guarding a bone."
Sū Huì's expression hardened at once. It was not a sharp gesture, but the tired smile vanished as she stretched out her calloused hand and gave a dry flick to the youngest's forehead.
"Ow!"
"Never repeat the filth those long tongues say at the stream," Sū Huì said, in a low tone, but heavy as iron. "People who live looking at the ground only see mud, Méi. A-Yuǎn had no one in this world and looked at everything as if he were only passing through. It was your sister's stubbornness that tied his feet to us."
Sū Huì turned back to the board, returning to push the dough with her fists.
"Some trees grow straight for everyone to see," the mother continued, her voice turning gentle again under the crackle of firewood in the stove. "Others grow twisted into each other. It doesn't matter what the village thinks, as long as the root holds when the wind hits. Let your sister take care of her husband in her own way, and go wash those hands to help me cut the turnips, because your father will need strong food today."
Yù Méi rubbed the spot on her forehead where she had been flicked, chewing the rest of the bread in silence while glancing sideways at the green path of the bamboo grove far away.
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Back in the cabin, while both moved on the bed, Zhì Yuǎn looked inside his wife's body. The structure he had built days before was undone and the heat that remained inside ran loose and without form. He locked his jaw and, with every thrust, began forcing the structure back, seizing the Yang in her chest to hammer the mold of axis, teeth, and rotation.
Yù Qíng choked and her eyes rolled.
"A-Yuǎn…" she whimpered, tearing his shoulders with her nails.
When the structure firmed, Zhì Yuǎn turned. The Yang broke and released a wave of pure Yin that spread through her channels, widening and cementing the walls until it tore a long and trembling moan from her throat.
The invasion continued heavy. Yù Qíng's thighs trembled hard and she stifled a scream in her husband's neck, arching her spine while the limit broke and her interior convulsed around his shaft, releasing the black and icy Yin.
The cold moisture touched Zhì Yuǎn's skin and he pulled that mass into himself, feeling the Yin rise through his veins and spread beneath his ribs. Applying the same method to himself, the pressure in his skull increased and the veins at his temples jumped as he shaped the axis below his sternum and crushed the cold against the cold.
Crack.
The mill in his chest turned. Yù Qíng's Yin broke and transformed into pure Yang, spreading through his channels and thickening the internal walls. Zhì Yuǎn's body contracted entirely, with sweat running down his back.
The first inversion was complete.
Two weeks of isolation ended any notion of time inside the locked cabin, where the only clock in the dark room was the constant and wet sound of flesh striking.
On the afternoon of the fourteenth day, the bed creaked under the friction that had lasted since the early hours without pause. Yù Qíng was face down, her face buried in the pillow and her teeth dug into the fabric, while Zhì Yuǎn held her wrists behind her and pulled her against himself with every thrust, sweat running down both their backs.
Zhì Yuǎn's limit broke and he drove his hips hard, coming deep inside her. At the same instant, Yù Qíng's body contracted violently and the black and icy Yin poured from her, rising straight through her husband's channels.
He pulled that Yin into his own mill and forced the rotation.
Crack.
The Yin broke and transformed into pure Yang, at the same time that Yù Qíng performed the inverse movement with the Yang he had poured inside her. They continued the process without stopping.
Second rotation. Third. Fourth.
On the seventh, only an extremely dense drop remained, which soon overflowed.
The pure Qi leaked from the meridians and invaded the flesh, the muscles, and the bones. Yù Qíng let out a muffled roar into the pillow with her entire body contracting, while the Yang descended heavily through Zhì Yuǎn's musculature. He felt his own fibers being torn and stitched again, thicker and denser, as the heat descended to the bones, melting the soft parts and hardening the cartilage. The pain was strong, but it ended drowned by the constant sensation of being inside her.
Yù Qíng arched her hips even further back, as if she wanted to feel him deeper even with the pain.
"Deeper…" she gasped, sweating and enduring the pull on her wrists without faltering.
When the early hours passed, the body needed to expel the filth accumulated over twenty years.
The friction changed as the sweat that ran from both their skins lost its normal texture, becoming thick, cold, and sticky while a foul, metallic stench took over the room. Yù Qíng choked and tried to get up, but her arms trembled, making Zhì Yuǎn pull back and sit on his heels.
A black and oily sludge ran from every pore, descending down his chest like pitch and covering her back and hair on the ruined sheet. Yù Qíng looked at her own hands with disgust and tried to move a little away from the soaked cloth.
"How disgusting…" she murmured, her voice strangled. "The body… rotted from the inside?"
Zhì Yuǎn looked at his own skin, feeling the bones and tendons clean and dense.
"The body is throwing out what no longer serves," he answered. "The pure Qi pushed the old filth out."
Yù Qíng blinked slowly, absorbing the words, but even with the relief the smell was still too strong.
"I can't breathe in here," she murmured, pushing herself to the edge of the bed. "The water in the basin won't be enough."
Zhì Yuǎn stood without his body trembling, even after all that time, and held his wife's arms to pull her up.
"The stream outside is deep at the northern bend," he said, walking naked to the log that locked the door. "Let's clean the skin before this sludge dries."
The northern bend of the stream cut through the bamboo grove with the water descending icy among the dark stones. Zhì Yuǎn entered the current until the water struck his chest and pulled Yù Qíng with him, noticing that the shock of the cold, which weeks ago would have made the bones ache, barely raised the skin of either of them because the remade body no longer reacted the same way.
They sank into the water and Zhì Yuǎn used his large hands to scrub his wife's shoulders, back, and face, removing the black sludge, while Yù Qíng did the same to him, scraping his chest and neck until the last dark filth was carried away by the current.
When they finished, Zhì Yuǎn stopped under the light of the waning moon that illuminated both bodies in the dark water. Yù Qíng's skin was different and had lost that more fragile aspect from before, without the calluses on her hands or the old marks of labor, leaving only a smooth surface when he slid his fingers along hers. His body had also changed, with the muscles of his chest and abdomen more defined and firm, free of the coal burn marks and the leather dried by the sun, while his gaze carried a more dangerous weight.
Yù Qíng felt her nails digging into her own palms as her stomach tightened with an old and possessive hunger. She placed her hands on his chest and pushed her hips against her husband's thigh.
"No woman from that village will look at you," she whispered, her voice low and sharp. "If they try, I'll tear their throats out on the riverbank."
Zhì Yuǎn held his wife's waist, lifted her from the water, and took two steps against the current, pressing her back against a large stone that stood on the bank. Yù Qíng choked when her bare skin touched the cold rock, but soon opened her legs and wrapped them around his waist, allowing Zhì Yuǎn to anchor his hips and enter her all at once.
Yù Qíng let out a hoarse moan with her nape striking the stone, and the friction began again in the water, heavy and fast. When she reached her limit, Zhì Yuǎn pulled her Yin into himself and the mill in his chest turned hard, breaking the ice to transform it into Yang while the inverse process solidified her channels even further.
The following weeks dissolved the counting of days, until, at the end of the third week, the water of the stream remained clear after the washing, ending the purification for good.
------
The midday sun sliced the bamboo room, where Zhì Yuǎn and Yù Qíng had been intertwined for a full day and night, maintaining the dense sound of flesh colliding in a heavy, continuous rhythm without a single pause.
Zhì Yuǎn's broad muscles burned the energy without fatigue and Yù Qíng's thighs locked his waist like cables, supporting the pull of every thrust without trembling. He sank the invasion and lowered his face, running his tongue along his wife's neck to collect the thick and sweet sweat over her collarbone, while the entire room smelled of the dense perfume of two refined bodies striking.
Yù Qíng arched her spine, scratching his shoulders, and pulled her husband's nape with urgency to crush her lips against his.
His wife's mouth opened and Zhì Yuǎn exhaled his own breath laden with dense Yang directly against her lips, making Yù Qíng swallow the hot energy before pushing her own icy Yin breath back into her husband's palate.
The friction drove both to the limit.
Zhì Yuǎn locked his jaw and sank his hips, pouring the Yang directly against the deepest walls at the exact moment Yù Qíng's muscles convulsed and released the torrent of her Yin. The massive exchange happened, the mills turned, and the pure energies thickened the channels of both even further.
When the mills finally stopped, silence filled the cabin.
Zhì Yuǎn ceased the movement and braced his forearms on the mattress to support his own weight. His dense musculature rested intact and ready to support more days of effort, but the pressure at his temples weighed like lead after a full day and night of grinding essences to the limit of their minds.
Yù Qíng turned onto her side, nestling her pale face against her husband's neck and drawing the air slowly while her fingers rested inert on his chest. Zhì Yuǎn closed his eyes and wrapped his arm around his wife's waist, letting the silence take over both of them. The body was already ready, and now they only needed to rest their heads.