The fifth day of isolation began with dry knocks on the bamboo door. The wood cracked, cutting through the silence of the room.
— Brother-in-law! Sister! — Yù Méi shouted from outside. — It's been four days! The broth's gone cold! You promised you'd teach me how to read the mine markings, A-Yuǎn! Open up!
On the bed, Zhì Yuǎn opened his eyes. He was about to answer when Yù Qíng's hand clamped tightly over his mouth. She was pressed against his side, staring at the locked door. Her nails scraped the sheet and her jaw tightened.
She pulled her hand away from his mouth and answered on her own, her voice hard:
— The mine's furnace almost dried out your brother-in-law's bones, Méi! He's burning with fever and he's staying in bed today. Go back to the main house and stop banging on this door!
Outside, Yù Méi went quiet for a second.
— But I brought fresh bread! — she protested, kicking the bottom of the door.
— Eat it on the way — Yù Qíng replied. — The lock stays where it is.
A muffled grumble came from outside, followed by the sound of footsteps walking away.
Zhì Yuǎn rolled onto his side and propped himself up on his elbow, looking at her.
— Fever? — he murmured.
Yù Qíng's jaw relaxed. A hungry smile appeared on her lips. She slid her hands behind his neck and pulled his burning chest against her cold breasts.
— You're always burning for me — she whispered. Her legs opened and wrapped around his waist.
Zhì Yuǎn moved his hips and thrust into her in one motion. Yù Qíng gasped, her fingers digging into his hair. The friction resumed.
As they moved, he looked inside her body. The gear he had built days earlier had come undone. The remaining heat was loose, shapeless. He clenched his jaw and, with every thrust, began forcing the structure back into place. He grabbed the Yang in her chest and hammered the mold — axle, teeth, rotation.
Yù Qíng choked. Her eyes rolled back.
— A-Yuǎn... — she whimpered, her nails tearing into his shoulders.
Once the gear was stable, Zhì Yuǎn rotated it. The Yang shattered and released a wave of pure Yin that spread through her channels, widening and cementing the walls. She let out a long, trembling moan.
The invasion continued, heavy and steady. Yù Qíng's thighs trembled hard. She muffled a cry against his neck, her spine arching as her limit broke. Her insides convulsed around his shaft, releasing the cold, black Yin.
The icy wetness touched his skin.
Zhì Yuǎn pulled that mass of cold into himself. The Yin climbed through his veins, spreading beneath his ribs. Then he applied the same process to himself. The pressure in his skull increased. The veins at his temples bulged. Below his sternum, he shaped the axle and crushed the cold against cold.
Crack.
The mill in his chest turned. Yù Qíng's Yin shattered and transformed into pure Yang, spreading through his channels and thickening the walls. Zhì Yuǎn's entire body tensed. Sweat ran down his back.
The first inversion was complete.
---
Two weeks of isolation had erased any sense of time. The door stayed locked. The only clock in the dark room was the constant, wet sound of flesh colliding.
On the afternoon of the fourteenth day, the bed creaked under nearly twelve straight hours of friction. Yù Qíng was on her stomach, face buried in the pillow, teeth clenched in the fabric. Zhì Yuǎn held her wrists behind her back, pulling her into every thrust. Sweat ran down both of their backs.
Zhì Yuǎn's limit broke. He drove his hips forward with force and came deep inside her. At the same moment, Yù Qíng's body convulsed violently. Black, icy Yin gushed out of her, surging straight into his channels.
He pulled that Yin into his own mill and forced it to rotate.
Crack.
The Yin shattered and turned into pure Yang. Yù Qíng did the reverse with the Yang he had poured into her. They kept going without pause.
Second rotation. Third. Fourth.
By the seventh, only one extremely dense drop remained.
That drop overflowed.
Pure Qi spilled from the meridians and flooded into flesh, muscle, and bone. Yù Qíng let out a muffled roar into the pillow, her entire body contracting. The Yang sank heavily through Zhì Yuǎn's muscles. He felt his own fibers being torn apart and stitched back together, thicker and denser. The heat sank into his bones, melting away the porosity and vitrifying the cartilage. The pain was sharp, but it was drowned out by the constant feeling of being inside her.
Yù Qíng arched her hips even further back, as if trying to take him deeper despite the pain.
— Deeper... — she gasped, sweating, enduring the pull on her wrists without weakening.
The night passed. The body needed to expel the waste accumulated over twenty years.
The friction changed. The sweat running down their skin lost its normal texture. It became thick, cold, and sticky. A foul, metallic smell filled the room. Yù Qíng gagged. She tried to get up, but her arms trembled. Zhì Yuǎn pulled back and sat on his heels.
A black, oily sludge was oozing from every pore. It ran down his chest like melted tar. It covered her back and clung to her hair. The sheet was ruined.
Yù Qíng looked at her own hands with disgust. She tried to pull away slightly from the soaked sheet.
— Disgusting… — she muttered, her voice strained. — Did the body rot from the inside?
Zhì Yuǎn looked at his own skin. His bones and tendons were clean and dense.
— The body is throwing out what it no longer needs — he answered. — The pure Qi pushed the old filth to the surface.
Yù Qíng blinked slowly, taking in his words. Relief came, but the smell was still overwhelming.
— I can't breathe in here — she murmured, pushing herself toward the edge of the bed. — The basin water won't be enough.
Zhì Yuǎn stood up. Even after hours of continuous effort, his body didn't tremble. He took her arms and pulled her up.
— The stream outside is deep at the north bend — he said, walking naked toward the log barring the door. — Let's clean our skin before this sludge dries.
---
The north bend of the stream cut through the bamboo grove. The water ran cold between the dark stones. Zhì Yuǎn stepped into the current until the water reached his chest and pulled Yù Qíng in with him. The shock of the cold, which weeks ago would have made their bones ache, barely raised goosebumps on their skin. Their rebuilt bodies no longer reacted the same way.
They sank into the water. Zhì Yuǎn used his large hands to scrub her shoulders, back, and face, washing away the black sludge. Yù Qíng did the same to him, scraping his chest and neck until the last traces of dark filth were carried away by the current.
Zhì Yuǎn stopped. The waning moon lit the two bodies in the dark water.
Yù Qíng's skin looked different. It had lost that fragile quality it once had. The calluses on her hands and the old marks of labor had disappeared. Zhì Yuǎn ran his hand over her fingers and felt that the roughness was gone. His body had changed too. The muscles in his chest and abdomen were more defined and solid, as if they had been forged. The burn marks from coal and the sun-dried, leathery skin had vanished. His gaze carried something heavier, more dangerous.
Yù Qíng felt her nails digging into her own palms. Her stomach tightened with an old, possessive hunger. She placed her hands on his chest and pushed her hips against his thigh.
— No woman from that village is going to look at you — she whispered, her voice low and sharp. — If they try, I'll rip their throats out by the riverbank.
Zhì Yuǎn grabbed her waist, lifted her out of the water, and took two steps against the current. He pressed her bare back against a large stone on the bank. Yù Qíng gasped when her skin touched the cold rock. She opened her legs and wrapped them around his waist. Zhì Yuǎn anchored his hips and thrust into her in one motion.
Yù Qíng let out a rough moan, her head hitting the stone. The friction resumed in the water, heavy and fast. When she came, Zhì Yuǎn pulled her Yin into himself. The mill in his chest spun violently, shattering the ice and turning it into Yang. At the same time, the reverse process continued solidifying her channels.
---
The following weeks erased any sense of days passing.
By the end of the third week, the stream water stayed clear after washing. The purification had finally ended.
The midday sun sliced through the bamboo room. Zhì Yuǎn and Yù Qíng had been locked together for twenty-four hours. The dense sound of flesh colliding maintained its predatory rhythm without a single pause.
Zhì Yuǎn's broad muscles burned energy without fatigue. Yù Qíng's thighs gripped his waist like cables, enduring the pull of every thrust without trembling.
He sank deeper and lowered his face. His tongue traced her neck, collecting the sweat along her collarbone. The liquid was thick and sweet. The room smelled sweet and heavy, the raw scent of two refined bodies colliding.
Yù Qíng arched her back, scratching his shoulders. She pulled his nape with urgency and crushed her lips against his.
Her mouth opened wide. Zhì Yuǎn exhaled his own breath, thick with Yang, directly against her lips. Yù Qíng swallowed the burning energy and pushed her cold, fragrant Yin breath back into his mouth.
The lethal friction pushed them to the edge.
Zhì Yuǎn clenched his jaw and drove his hips forward. The limit broke. He poured Yang straight against her deepest walls. Yù Qíng's muscles convulsed, releasing her own torrent of Yin. The massive exchange took place, the mills turned, and the pure energies further thickened both of their channels.
When the gears stopped, silence filled the cabin.
Zhì Yuǎn ceased his movement and braced his forearms on the straw mattress, holding his own weight. His dense musculature remained intact, vibrating with strength to endure more days of effort.
But the pressure in his temples was pure lead. The nonstop grinding of essences for twenty-four hours had drained both of their Seas of Consciousness to the very edge of dark fragmentation.
Yù Qíng turned onto her side, nestling her pale face against her husband's neck, breathing in the lethargic scent of his skin. Her breathing was slow and heavy, her fingers resting limply on his chest.
Zhì Yuǎn closed his eyes, his arm wrapping around her waist. The silence of rest settled over them. They had stopped only to rest their heads. The body was already complete.