The wind along the Golden Core Avenue had gone completely still. It was the kind of quiet that settles between two hearts, not empty, but full of unspoken things. Above them, the stars glimmered like spirit pearls scattered across a vast length of black silk.
Su Min sat close beside Xie Yingying outside their temporary cave. Their bedrolls and alchemy scrolls were tucked safely inside. Her sleeve brushed against Xie Yingying's as she shifted, a casually bold move, though her voice held a soft, almost hesitant undercurrent.
"Yingying," she murmured, "come closer. I won't bite."
Xie Yingying didn't answer right away. Her gaze slid sideways, cool and unreadable, as if she was weighing the stars themselves instead of the words. But after a thoughtful pause, she moved. Not with hesitation, but with a quiet, deliberate intent. Her slender hand reached out and settled gently over Su Min's.
The contact was light. Perfectly still. Like a bell waiting to be rung.
Su Min let out a slow breath, turning her hand over to lace their fingers together. "There," she said, her voice almost playful. "Look at us. Like a pair of shy maidens in a mortal play, hiding behind fans and coy glances."
Xie Yingying's lashes lowered, but not in denial. Her lips quirked in a faint, almost imperceptible smile. "You are the one who is blushing."
"Only because your hand feels like snow," Su Min shot back, her own cheeks warm. "Cultivating with the moon has turned you into an ice spirit."
But she didn't let go.
And Xie Yingying didn't pull away.
That night passed quietly. So did the next one, and the one after that.
What began as a shared handhold became something steadier, a silent agreement. Xie Yingying allowed Su Min's arm to curl around her waist during their morning meditations. She leaned into Su Min's warmth without flinching. During long nights under spirit-infused blankets, there were quiet conversations and even softer touches. A brush of lips to a cheek. A sleeping breath against a shoulder. A quiet, mutual kiss shared when neither of them could pretend it had not already begun.
It was not a sudden hunger. It was a kindling. Slow. Intentional. They had time, a luxury in their long lives, and so they took it.
Until tonight.
The glowmoss along the quartz cave walls shimmered in pale green hues, casting gentle, waving light across the bedroll where an ancient scroll lay unrolled. The ink of the Harmonization Manual was dark and sharp, looking almost austere next to the warm, living pulse they could both feel between them.
Intimate Dual Cultivation: Solar and Lunar Resonance Method.
The words were so precise. So technical.
Yet as Xie Yingying's hand brushed Su Min's again, the words on the page seemed to fade into background noise. All Su Min could feel was the heat coiled low beneath her own skin, patient but undeniable.
They had taken this slowly. Painfully slowly. Hands first, then waists, then the tentative press of lips to cheeks, then, finally, lips to lips. Each step had been a silent negotiation, an agreement between two people who had never let anyone this close before.
But tonight was different.
Tonight, they were not just lovers. They were cultivators. Partners.
"The first step," Xie Yingying murmured, her fingertip tracing a line of gold-threaded calligraphy, "requires the full synchronization of our energy pathways. It begins with a kiss."
"Just a kiss?" Su Min grinned, the familiar tease a comfort. "I thought the Ancients would at least ask for some tongue."
Xie Yingying gave her a look, dry and unimpressed, but the tips of her ears turned a bright, telling crimson.
They both took a steadying breath. This was the first time they would try the real thing. Not idle touching. Not stolen warmth beneath silks.
Su Min's body shimmered with a sudden flare of white light. Her qi surged, radiant and brilliant, a miniature sun igniting deep within her meridians.
"I will not last long in this form," she warned, the grin still on her lips but trembling at the edges with the strain. "Three minutes. Maybe four if you flatter me."
Xie Yingying's breath caught. It was not just her vision. Her very own Lunar Sovereign Physique was reacting, trembling with a deep, instinctual pull. This was not like before. Su Min's Solar Sovereign Physique had fully awakened, even if it was only temporary. Her fingers tightened around Su Min's, her pupils widening as her body was drawn to its counterpart like something starved.
Su Min leaned forward, her lips brushing against hers.
The kiss was gentle. Soft. Their lips met in perfect silence, but the moment Su Min pushed just a fraction deeper, her white qi surged outward, threading into Xie Yingying's mouth.
Xie Yingying's back arched.
A low moan slipped free.
She had not meant to make a sound, but the moment their tongues touched and that radiant qi slid into her channels, her mind went blank. All the techniques, all the sequences, all the elegant diagrams from the scripture were gone.
All that remained was heat. A deep ache. A sudden, overwhelming desperation.
The kiss turned ravenous. She surged forward, her hands tangling in Su Min's robes, her body pressing flush against hers. The cold detachment that usually clung to her like armor was gone, replaced by something molten and desperate. Su Min barely had time to register the shift before Xie Yingying's tongue swept into her mouth, stealing her breath and her thoughts, and then her balance, as Xie Yingying pushed her back onto the bed.
"Yingying," Su Min gasped, but the protest died in her throat as Xie Yingying straddled her, her hair spilling down like moonlight over them both. Her eyes were dark and hungry, her usually composed features flushed with raw need.
"You," Xie Yingying breathed, as if the word itself burned her.
The scripture's instructions were forgotten. There was only this, the slide of skin, the heat between them, Xie Yingying's fingers trembling as they undid Su Min's sash.
And Su Min, overwhelmed by that raw sincerity, by the trembling restraint that was barely holding Xie Yingying together, gave in.
Their robes fell open like petals loosening in a night breeze.
Xie Yingying's softness pressed against Su Min's thigh, already damp with desire. She rocked against her, clinging to the warmth of the Taiyang qi like a drowning woman. Her body, so attuned to the Yin resonance, bloomed under the heat. She was so sensitive she gasped when Su Min's fingers brushed against her inner thigh.
Su Min groaned softly. "You are burning up. Who is the cold one now, huh?"
But her teasing faltered as Xie Yingying kissed her again, not just with her lips, but with her entire body. She pressed their cores together, grinding and seeking, trembling with every stroke. Wet, hot, and slick, they moved in sync, their hips meeting in a desperate, frantic rhythm.
"Su Min, more, do not stop," she gasped, her voice breaking, no longer the aloof Holy Maiden but a woman completely undone.
A choked moan escaped Xie Yingying's lips, her back arching, her nails biting into Su Min's shoulders. She moved like a woman possessed, chasing the pleasure that the resonance between their physiques amplified tenfold. Every roll of her hips was frantic and starved, as if she could fuse them together through sheer force.
Su Min gripped her waist, her own breath coming in ragged bursts. She had kissed Xie Yingying a hundred times, had learned the shape of her body in slow, tender explorations, but this was something else entirely. This was a wildfire.
Xie Yingying's climax hit her like a breaking wave. She cried out, her fingers twisting in the sheets. The sight of her, proud and icy Xie Yingying, unraveling so completely, sent Su Min tumbling after her. Pleasure crested in a white hot rush that left them both shuddering.
For a single, suspended heartbeat, they clung to each other, sweat slick and breathless.
Three minutes.
Su Min's Taiyang qi started to recede, the brilliant light fading from her skin.
And as it faded, so too did the maddening haze in Xie Yingying's mind. She slowed, panting, her face buried against Su Min's neck. Their bodies were still entangled, their cores still pressed together, soft and wet and spent.
"I," Xie Yingying whispered, her breath shaky, her lips brushing against Su Min's collarbone, "I lost control."
Su Min ran a soothing hand down her back, feeling the fine tremors that still ran through her. "You did not force me. I wanted it too. I just, well, I was not expecting the holy maiden to be such a beast."
A soft, breathless chuckle escaped Xie Yingying. Then a comfortable quiet fell again.
No words of love were exchanged. None were needed.
Their breathing slowly steadied, their bodies still nestled together in the quiet warmth of the cave. The Golden Core Avenue whispered around them, the stars above indifferent, and yet, something sacred had happened.
Two Sovereign legacies had touched. Two hearts, once uncertain, now beat in tandem.
And in that silence, something began to grow.
Something far more terrifying, and far more precious, than power.
Love.
—
The morning after, the wind carried the scent of dew and wild lotus, but Su Min did not smell it.
She was too busy staring at Xie Yingying, who, for once, was not sitting in composed stillness with that usual frost bitten calm. No, today the holy maiden was curled beside her, her chin resting on her folded arms, her long hair splayed out across Su Min's lap like flowing midnight.
Her eyes were half lidded. Her lips were parted slightly. She was silent.
But she was watching, her gaze intense and focused.
"You are staring," Su Min muttered, brushing a strand of hair from her lover's cheek. "That is creepy, you know."
"You kissed me first," Xie Yingying said simply, as if that explained everything.
"That was yesterday."
Xie Yingying did not respond. Instead, she reached for Su Min's hand and laced their fingers together with a quiet possessiveness.
Su Min sighed, a fond exasperation in the sound.
"I know that look," she said. "Do not even say it. The answer is no."
"I want to try again."
Su Min froze. "Yingying."
The woman sat up, her eyes gleaming with that subtle, hungry light again. "I will try to follow the scripture. Step by step. I promise."
"You said that last time." Su Min groaned, the memory vivid. "Right before you jumped me like a starving beast in heat."
Xie Yingying's ears flushed a bright red, but her voice was steady, unwavering. "Then do not activate your Solar Sovereign Physique so early."
"That is the first step in the method," Su Min countered.
"I will endure it," she said, her tone leaving no room for argument.
The second attempt began with promises. They kissed. Slow. Deliberate. The kind of kiss meant to remember a person by, not just to take.
Su Min let her Solar Sovereign Physique awaken, a cautious trickle of power.
Immediately, she felt Xie Yingying tremble against her.
But the Holy Maiden did not break.
Not yet.
She deepened the kiss. One hand was on Su Min's cheek, a grounding touch. The other slid to her waist, then her hips, then lower.
"Yingying," Su Min's voice faltered as she was gently pushed back onto the bed. Xie Yingying's Taiyin energy swirled around them like a cool breeze against her heated skin.
"I want to try something," Xie Yingying murmured, her breath ghosting over Su Min's ear like moonlight on still water.
Su Min huffed, her half lidded eyes gleaming with suspicion. "What happened to restraint?"
"This is restraint," she replied, her voice soft and almost reverent, but it carried that dangerously sweet undertone that always meant trouble. "I am just, taking my time."
Her hand drifted lower, purposefully.
Su Min inhaled sharply as fingertips found the soaked warmth between her thighs. But Xie Yingying did not rush. There was no grinding, no mindless urgency this time.
Just the lightest graze of her fingers along swollen petals, wet and trembling with anticipation.
Tentative at first.
A stroke here. A brush there.
Teasing.
Mapping her with a curious reverence, as if she were trying to learn Su Min's every tremor by touch alone.
Then, slowly, her fingers slid between the delicate petals, the slick heat welcoming her in.
She did not enter, not yet. Instead, she teased gently along the tender seam, spreading the slickness with each pass. Then she moved upward, gently circling a certain tender bud nestled there. Su Min's hips twitched, a ragged moan spilling from her lips before she could catch it.
"There," Xie Yingying whispered, almost to herself, a note of discovery in her voice. "You react so sweetly right, here."
Her fingertip danced around the delicate bud, slow and knowing, drawing soft gasps and half formed curses from Su Min's mouth.
And only after Su Min was pliant and melting under her touch, her eyes glazed and her breath hitching, did Xie Yingying finally let her fingers sink inside.
The tight, wet heat clenched instinctively around her touch.
The motion was steady. Deep. Unhurried.
Su Min's back arched off the bedroll. "Yingying." Her voice cracked, half a moan, half a plea.
Xie Yingying leaned down, brushing her lips over Su Min's collarbone. She nipped there lightly, barely enough to sting, then whispered, "So this is what you feel like inside."
Her thumb resumed its slow, intoxicating circles as her fingers curled, gently and experimentally, within Su Min's soaked warmth.
"You little, ngh." Su Min arched as another finger joined, her thoughts scattering completely the moment the pressure and rhythm aligned.
Xie Yingying listened with her whole body. Every flutter of inner walls, every gasp, every unconscious arch of hips became her guide.
Her own breaths grew ragged. Her rhythm faster. Her lips found Su Min's again and this time the kiss was messy and desperate, all tongues and teeth and shared breath.
Restraint shattered.
Again.
—
But it did not stop there.
The next night, Xie Yingying pressed against her back as they meditated, her breath ghosting her ear.
"Just one more time."
"No."
A soft sigh. Then fingers traced along Su Min's collarbone, a feather light touch. "What if I beg?"
"Still no."
"What if I do this?" A daring kiss brushed Su Min's neck. A palm slid under her sash, warm against her stomach.
Su Min cursed under her breath. "Yingying, do not seduce me like some desperate widow."
But her protest was weak. And her body was weaker still.
It was late another evening. The moon hung high, casting silver light over the stone veranda where Su Min lay sprawled on her side, lazily flipping through a tattered ancient scroll. A half empty teacup steamed beside her. She looked perfectly at ease.
Until soft, familiar footsteps padded over.
Xie Yingying knelt behind her, silent and calm. Too calm.
Su Min did not look up. "No."
"I did not say anything."
"You are thinking it. I can hear it."
A small, telling pause.
Then, "Just one more time."
Su Min groaned, dragging the scroll over her face in frustration. "You said that three times ago."
"I know."
"Yingying."
"Mm."
There was a long silence, filled only with the sound of the night insects.
Then, fingers. Cool fingertips brushed the nape of her neck, lifting her hair as if by accident. Su Min froze.
"You are shameless," she muttered into the scroll.
"I learned from the best," Xie Yingying said, utterly deadpan. Then she leaned closer. Her breath grazed Su Min's ear. "You make such pretty sounds when I touch you."
Su Min flushed from her neck to her hairline. "That is because you do not just touch. You devour."
"So let me devour you. Just once more."
A hand crept over her waist, slow and patient, while lips kissed the shell of her ear.
Su Min made a strangled noise. "Yingying."
"If you really want me to stop," she whispered, her voice a low, tempting hum, "you will have to push me away."
The hand slid lower. The kiss deepened, now at her jaw, soft and sweet and maddening.
Su Min did not move.
She did not even pretend to push.
Instead, she growled, "You manipulative little moon demon."
Xie Yingying smiled, a small, pleased, victorious expression. "Then I take that as a yes."
—
Night after night, they tried again.
And again.
—
Su Min sat cross legged on the floor of their dwelling. Her robes were loosened, her hair tied up in a lazy knot as she flipped through a jade slip of alchemy formulas, her brow furrowed in concentration.
A quiet rustle of silk was her only warning.
Xie Yingying approached with the soundless grace of snowfall.
"I am studying," Su Min said without looking up.
"I noticed."
Cool fingers trailed over her nape. Uninvited. Unhurried.
Su Min exhaled slowly, trying to focus on the formula. "We agreed to wait until your control improves."
"I am controlling myself right now." Xie Yingying sat behind her, close enough that their knees brushed. Her voice was calm. Too calm. "You have not seen what I would do if I was not."
"Threatening your lover with lust?" Su Min muttered, sliding the jade slip shut with a click. "Truly holy of you, Maiden Yingying."
A hand ghosted down her spine, leaving a trail of goosebumps. "You are the one who called me your personal yin furnace."
"I was joking," Su Min hissed, her skin prickling under that featherlight touch.
A pause. Then,
"Then let me be serious."
There was a shift in the air, a gentle heat curling through the usual Taiyin coldness that surrounded her. Su Min's breath caught as Xie Yingying leaned in, her lips brushing the shell of Su Min's ear.
"You smell like fire and medicine," she murmured, her voice low and reverent. "It clings to you."
"Because I am an alchemist?" Su Min retorted, her heart beating faster.
"No," Xie Yingying whispered, her breath warm. "Because you burn me."
Su Min stiffened, then slowly turned her head to meet that intense gaze.
"Are you poetic now?"
"I am desperate."
There was no tremble in her voice, no visible blush. Just a steady, dangerous intensity in her eyes. Taiyin energy gleamed in her pupils like a quiet, bottomless hunger.
"Yingying," Su Min warned, her resolve crumbling.
But Xie Yingying reached forward and, very slowly, undid the knot of Su Min's sash.
"Let me borrow your fire," she whispered. "Just once more."
Su Min groaned, letting her head fall back. "You said that last night."
"And the night before." A cool kiss landed at her jaw. "I am still cold."
"You are insatiable."
"I am yours."
Silence. Heavy and charged.
Then Su Min dropped her jade slip with a clack, twisted around, and seized Xie Yingying's chin between her fingers.
"You are lucky I like insane women."
Xie Yingying smiled, a true, bright thing, and leaned in to kiss her.
—
And again.
Sometimes they began with good intentions, with scriptures recited and the proper channels aligned.
Yet it all ended the same, with Xie Yingying's moans vibrating against Su Min's lips, her body arching like a bowstring pulled taut by the Taiyang's relentless sun. Their limbs tangled, the scriptures were forgotten, and every gasp was swallowed between them as she lost herself in the heat, unable to resist, unable to stop.
Like water always finding cracks in stone, their best intentions eroded. A correctly aligned handhold would slide up a thigh. A shared breath would become a shared mouth. The scriptures might start open on the bed, but they would inevitably be crushed under grasping hands or pushed onto the floor.
—
Su Min started teasing her again, a familiar game.
"Aren't you supposed to be the noble, untouchable Holy Maiden?"
Xie Yingying raised a brow, a glint in her eye. "You are the one who called me your personal yin furnace when you thought I was asleep."
Su Min choked on air. "Excuse me. I said you were burning up. That is completely different."
"Oh?" Xie Yingying leaned in, her lips brushing Su Min's ear, her voice a low purr. "Then why did you say it like you wanted to throw me into your bed and refine me?"
Su Min groaned, covering her face with her hands. "You have gotten shameless."
"I learned from the best." Then she bit her lip, her eyes glittering with challenge. "I dare you to say it again."
Su Min leaned in, her voice dropping to a low, sinful whisper. "My personal yin furnace."
"Then ignite me properly."
And Su Min, every single time, obliged.
—
The moonlight spilling into their dwelling was soft, too soft for the storm simmering in Xie Yingying's chest. Su Min had returned late that evening, smelling faintly of spirit herbs and fire essence. Her sleeves were dusted with gold ash, her usually sharp eyes glowing with quiet triumph after a successful refinement.
The Golden Core Avenue had buzzed with her name all day. Dozens of cultivators had crowded around her cauldron, desperate for her notice, for a pill, for a glance. And among them, Xie Yingying had seen it.
The look in their eyes.
Greedy. Reverent. Hungry.
Especially that Holy Son from the Azure Spirit Sect. He had been smiling like he thought her Min'er could be wooed with mere sect prestige and flattering words.
Now, Su Min was lounging on the bed, sipping tea as if nothing of consequence had happened.
"You are awfully quiet tonight," Su Min said, setting her cup down. "Or is the holy maiden pouting?"
Xie Yingying did not answer with words. Instead, she came forward. Her touch lingered on Su Min's wrist.
Cool. Deliberate.
"Something wrong?" Su Min asked, her tone shifting to something more gentle, more concerned.
Still no reply.
But Xie Yingying's lips brushed against the base of her throat. A kiss, soft. Then another, lower. A third, this time not so gentle.
A faint scrape of teeth.
Su Min gasped when she felt the pull of a bruise blooming on her collarbone.
"Yingying."
No answer. Another bite followed, lower, closer to her shoulder. Then a third one just above her collarbone, where no robe could hope to hide it.
Another kiss, harder this time. Her lips were cool, but the press of them left behind a heat that pulsed with possessive intent.
"I should mark you," Xie Yingying whispered, her voice thick with emotion. "So they know you are not, available. They looked at you like they had the right to."
Su Min stilled, understanding dawning.
"You mean the Holy Son?"
"All of them."
A long silence stretched between them. Su Min let out a slow breath, her body relaxing slightly into Xie Yingying's arms. Then Xie Yingying pushed her gently onto her back, straddling her hips.
Her hands slid down, parting Su Min's robe with a reverence that was also a claiming, like peeling open a sacred lotus bloom. Her lips returned to the hollow of Su Min's throat, lavishing it with kisses, some soft and apologetic, some sharp and branding. Su Min arched slightly beneath her, warmth pooling fast and undeniable.
"Yingying," she murmured again, but softer this time, helplessly fond. "You are being ridiculous."
"This," she said quietly, brushing her fingers along Su Min's chest, "is mine."
Her lips found the curve of Su Min's breast, sucking hard enough to leave a dark bruise. Then lower, dragging her teeth across the skin with maddening slowness. Each mark left behind an echo, evidence of a want and a need and a fury she could not express any other way.
Her kisses trailed lower. Another bite. A lick over the sting. Another mark where no one would ever see but her.
"And this."
Her fingers dipped between Su Min's thighs, parting her petals with reverence, but also with a fierce urgency.
"Also mine."
Then she slid down, kissing Su Min's abdomen, trailing her tongue until she reached the soaked petals below. When she licked, slow, languid, and deliberate, Su Min cried out softly, her fingers twisting in the sheets.
Xie Yingying did not rush this time.
She worshipped her.
Possessed her.
Made sure that for every look Su Min received in the daylight, she would remember who held her at night.
That night, Su Min's thighs bore the blossoms of possessive kisses.
Her neck was bitten, reddened, claimed for all to see.
And her heart?
It was already marked, long ago.
—
Years passed. Then decades.
Through every moonlit night on the Golden Core Avenue, their bond deepened. Their synchronization improved, their control along with it.
Until one night, Xie Yingying did not lose control.
They kissed, gentle at first. Then deeply, with a focused intent.
Taiyang and Taiyin qi spiraled between them, not clashing, but harmonizing in perfect, breathtaking resonance. Their scriptures aligned step by step, breath, posture, and intent merging into one.
Su Min's Taiyang light flared, brighter and more stable than ever before.
Xie Yingying's Taiyin channels opened in full, receiving it not with desperate hunger, but with serene acceptance.
And then,
Everything changed.
Their consciousnesses expanded, twining together into a vast, shimmering river of insight. They saw streaks of cosmic law, the rhythm of the cosmos, the uncountable, glittering threads of the Dao stretched out before them in an infinite tapestry.
It was not just dual cultivation.
It was transcendence.
They saw the flow of time, a river of silver and gold.
The fracture in the heavens, a scar on the face of the world.
Even Su Min, who had once glimpsed profound truths through her rare Insight ability, had never seen this much, or plunged this deep.
Her breath caught. "This is, beyond anything."
But then,
The Taiyang qi dimmed, flickering like a guttering candle.
Her core trembled, straining at its limits.
And the light collapsed.
Su Min's body jerked, her Solar Sovereign Physique fading away into nothing. The brilliant conduit snapped. Their shared connection collapsed like a shattered formation, the vision of the Dao ripped from their grasp.
They both gasped, pulled from the brink of enlightenment like drowning cultivators dragged from the depths of the sea.
Xie Yingying was the first to speak. Her voice was soft. Almost afraid.
"Again?"
"No." Su Min's voice was raw, strained. She looked pale, drained. "Not again. I barely held on this time. If we keep forcing it, we will suffer Dao injuries. Our foundations could crack."
"But we were so close," Xie Yingying whispered, the loss aching in her voice.
"I know." Su Min snapped, then immediately softened, reaching for her. "I know. But what use is enlightenment if it shatters us before we ever reach the other shore?"
Xie Yingying looked down, her shoulders slumping in rare defeat.
Su Min reached for her hand, their fingers intertwining.
Their touch was not with heat this time, but with the sober warmth of restraint.
"Someday," Su Min whispered, a promise in the quiet, "you will hold back. I will break through. And we will make it. Together."
Xie Yingying nodded, quietly, the fight gone out of her, replaced by a patient resolve.
Until that day, they sat together, watching the stars, no longer chasing the Dao with frantic hands.
But learning, slowly, how to walk toward it. Together.
===
[Notes]
Because this chapter's theme is dual cultivation, I want to expand more on the concept. One of the most common reasons rare physiques are so highly sought after is because of their compatibility with Dual Cultivation (双修, shuāng xiū)—a practice where two cultivators cultivate together to enhance their progress, often achieving results far faster than they would alone. Dual cultivation typically comes in two forms:
Intimate Dual Cultivation (双修, shuāng xiū): This form of dual cultivation is practiced through sexual intimacy, allowing for a deep, physical connection that boosts cultivation speed significantly. Those with matching attributes, such as a Pure Yang Body with a Pure Yin Body, can achieve rapid breakthroughs in their cultivation. However, this type of cultivation can also be exploited by unscrupulous cultivators who force their partners into these relationships solely to accelerate their progress, stripping the act of any consent or affection.
Casual Dual Cultivation (辅助双修, fǔzhù shuāng xiū): A less intimate form that involves simply holding hands or touching the other person's back, still requiring physical contact to connect their energies. Matching attributes still offer a boost, though not as substantial as in intimate dual cultivation. This practice is considered safer but is still sought after for the benefits it provides.
For cultivators of rare physiques, dual cultivation offers a quick path to power but also exposes them to manipulation, coercion, and even assault by those who wish to exploit their unique energies. But in most novel, the term dual cultivation is often used on the intimate ones.
For more information about this you can read on this link
That's also the reason why in the chapter "The Crowded Inheritance Grounds" telling that Xie Yingying is very wary to man. Because Lunar Sovereign (Taiyin) Body is also top tier cauldron (because this physique is top tier Yin physique) in this novel, making her often being targeted for her physique.
As for Su Min, even if she didn't activate her Taiyang qi and become Solar Sovereign Body, inside her body still have yang attributes, meaning that if she did casual dual cultivation with Xie Yingying, it still help them to get more boost on their cultivation.