Work Header

Sex, Science, and True Love: A Rigid Analysis of the Practical Applications of Dual Cultivation

Chapter Text



“I’m just saying,” Li Baoyang argued, holding up a pacifying hand, “you don’t know that dual cultivation isn’t a real thing. I mean, it’s everywhere in the literature.”

“Only if by ‘literature,’ you mean Nie Huaisang’s porn collection,” Jiang Cheng retorted. “No offense, Nie-xiong.”

“None taken,” Nie Huaisang replied easily. “Believe me, I also wish dual cultivation was real. Then maybe I’d be able to develop my golden core as quickly as the rest of you.”

“I’m not sure you and your right hand count as dual cultivation—” Li Baoyang teased, and immediately ducked to avoid being swatted by Nie Huaisang’s fan. “But seriously though, there’s so much of it in ah, Nie-xiong’s quality literature—”

“You’re welcome, but you’re not forgiven.”

“—that maybe someone actually did manage to dual cultivate, and that’s how the idea got passed down.”

“I once heard a rumour that this is how Lan An and his cultivation partner did it,” Ma Qiao piped up. “Which, I mean, if anyone could…”

“The Lans are far too boring and repressed for something like this,” Wei Wuxian said, with the authority of one who had been resoundingly ignored by a Lan for the past month. “Can you imagine Lan Wangji dual cultivating? Or Lan Qiren?”

There was a long and uncomfortable silence where everyone assembled imagined just that, and immediately wished they hadn’t. 

Even Wei Wuxian winced. “Sorry.”

“And with that bit of nightmare fuel,” Jiang Cheng said, glaring at Wei Wuxian, “we should probably turn in. It’s almost hai hour, and my knees still haven’t recovered from the last time we were caught out after curfew.”

Later, as Jiang Cheng and Wei Wuxian headed back to the Jiang sect quarters, Wei Wuxian turned to him and said, “Hypothetically, if dual cultivation was possible, would you do it?”

Jiang Cheng considered it. “No. I don’t want to rely on someone else for my cultivation. Any power I achieve, I want to know that I did it on my own.” He glanced over at Wei Wuxian. “Would you?”

“Maybe.” Wei Wuxian shrugged. “I think it’s kind of romantic — sharing my spiritual energy while sharing my body and growing together as a couple. I guess it would depend on my cultivation partner.”

“No one would be crazy enough to be your cultivation partner, anyway.”

Wei Wuxian gasped. “How dare you? I’m a great catch! I’m charming, handsome—”

“Incredibly annoying, a complete slob—”

Wei Wuxian whacked Jiang Cheng with Suibian. Jiang Cheng kicked him in retaliation, just as the door to their house slid open. 

“What are you two fighting over now?” Shijie asked, with an amused, fond smile. 

“Shijie!” Wei Wuxian whined, taking shameless advantage of her presence to hide behind her shoulder. “Jiang Cheng is bullying me.”

“He deserved it,” Jiang Cheng said, unrepentant.

Wei Wuxian couldn’t argue with that. He stuck out his tongue at Jiang Cheng anyway. 




He’s falling. 

The sky is a monstrous, spinning maw above him, ringed with cragged teeth. Shrieking wind deafens him, claws at his hair and skin, rips away every scream, every thought, every breath.  

He’s going to die. 

And then something swells up beneath him, immense and ancient and always, always hungry. Resentful energy spews out of it like blood from a gaping wound, an endless howl of death and despair. It reaches for him, burrows its way under his skin and deep into his flesh. He struggles, but he has nothing left to fight with, no weapons, no spiritual energy — nothing but pain and fear and a singular, devastating thought:

       Please, please let me die.


Wei Wuxian bolted upright in bed, gasping for air, flute brandished before him like the sword he no longer carried.

Dark, intricately carved wood rose in slender beams around him, held together by metal brackets at the ceiling and floor. Silk banners hung from the rafters, embroidered with a black, snarling beast: the sigil of the Nie Clan. 

He was in Qinghe, in the Unclean Realm. 

His pulse was rabbit-quick, his skin clammy and cold. Resentful energy seeped out of him in curling wispy swirls, taking advantage of his lapse in control to slither along the floor and crawl towards the windows and doors. Caged in his qiankun pouch, the Yin Tiger Seal throbbed like a beating heart. 

Slowly, he lowered Chenqing and folded his body into a cross-legged meditation pose, hands on his knees, eyes closed. With his gaze turned inward, he focused on the riotous tangle of resentful energy churning in him, barely contained by skin and will. He tightened his grip, and it fought him, straining at the seams of his control. Breath by breath, he dragged it back, forced it down into the hollow where his golden core used to reside. 

Eventually, the resentful energy settled, and Wei Wuxian opened his eyes. 

Silence greeted him, and the deep blue gloom of pre-dawn. He sighed and scraped himself off the bed, feeling somehow more tired now than before he’d fallen asleep. His body ached like he’d just been beaten, but he was starting to get used to the low thrum of pain that accompanied his waking hours. 

He’d been fighting this battle for months now, nearly constantly. It wasn’t getting any easier. Resentful energy swarmed around him, eager to be used, even more eager to use him. The Yin Tiger Seal helped a little, acted as a sink for the resentful energy to channel into, but it still felt—

“Like snatching a grain of rice from a fire,” he quoted, and laughed. It sounded brittle and hollow in the empty air. “Lan Zhan was right. As always.”

At least Lan Zhan was speaking to him again, though he could have done without the uncomfortably probing questions. It was ironic, really — when they’d first met, he’d clamoured for even a sliver of Lan Zhan’s attention like a sapling starving for light. Now, when he was stuffed full of secrets, Lan Zhan’s focus blazed down on him with the intensity of a noonday sun, scorching away any concealing shadows. 

He rubbed his eyes, licked dry lips. The jar of wine he’d picked up from dinner last night was empty, and it was still too early for the kitchen staff to unlock the stores. Even the Lans wouldn’t be stirring for another hour. And he didn’t want to go back to sleep. 

There were books he could read. The Nie sect had been generous in allowing the Jiang family — and by extension, Wei Wuxian — access to their library. Unsurprisingly, most of the collection favoured military history, though there were a few interesting selections about the Nie clan methods of cultivation by sabre. Wei Wuxian picked up one of those books, lit a few candles, and sat back down on the bed.

He was just getting acquainted with the narrative style — which was clear and concise, if a little prosaic — when a soft knock sounded on his door. 

“Wei Ying.”

Wei Wuxian looked up. No silhouette was visible through the paper screen, but he would know Lan Zhan’s voice in a thousand other voices.

He put away the book and went to open the door. “You’re awake early.”

Even at this hour, Lan Zhan looked impeccable, an ethereal vision clad in gleaming white, with a white-wrapped package strapped across his back. “As are you.” 

Wei Wuxian shrugged, taking a step back to allow Lan Zhan entry. “Couldn’t sleep.”

Lan Zhan nodded. His dark eyes swept over Wei Wuxian, keen and piercing. “I want to play for you,” he said, and slung the white package off his shoulders. “To calm your spirit.”

The white wrapping fell away as Lan Zhan set it on a low table: a qin, well-used, but beautifully carved and maintained. Wei Wuxian fought the urge to groan. 

Something of that must have shown on his expression anyway, because Lan Zhan frowned. “You said you would let me help you,” he reminded.

In hindsight, Wei Wuxian supposed he really should have expected this, after their rooftop conversation just a few hours ago. In his defense, that conversation had literally happened just a few hours ago, which wasn’t nearly enough time to think of either an excuse to avoid Lan Zhan for the rest of the war, or a convincing enough reason to make Lan Zhan give up on him. 

“I didn’t mean right now,” Wei Wuxian protested tepidly. “Besides, I thought such techniques are a closely-guarded Lan clan secret.”

Which was not a concession, though Lan Zhan seemed to think otherwise, as he sat down at the table and nodded for Wei Wuxian to take his place back on the bed. “Some are,” he said. “Others, we may share with those whom we trust.”

A knot tightened in Wei Wuxian’s chest, then loosened all at once. He swallowed hard, opened his mouth, and closed it again before it could betray him. Wordlessly, he drew a silencing spell on a blank talisman, and sent it off to seal the door. Then he returned to the bed, sat back down in the cross-legged meditation pose, and closed his eyes. 

The first note of Lan Zhan’s song rang bell-clear in the silence, infused with so much spiritual energy that it cut through the air like a ray of sunshine through dense stormcloud. Wei Wuxian hadn’t entirely been deflecting when he’d said, yesterday, that Lan Zhan’s cultivation had improved in their time apart. He’d heard that they were calling him Hanguang-jun now — a fitting name. 

“It’s pretty,” Wei Wuxian murmured, as Lan Zhan continued to play. “Does the song have a name?”

“No talking,” Lan Zhan responded shortly, but then relented enough to add, “Its name is ‘Cleansing.’”

Another fitting name. Wei Wuxian remembered from his lessons at the Cloud Recesses that Lan Sect had a collection of music that could affect the spirit and temperament. This must have been a song from that collection. Wei Wuxian could feel the way it was supposed to work — the music sank into him, spiritual energy clearing away any resentful energy in its path as it gathered in his meridians and concentrated low in his belly. 

And then slid off his empty core like raindrops on polished stone, and dissipated into nothingness. 

That particular wound was old now, its pain beginning to fade. Wei Wuxian opened his eyes again. 

Lan Zhan was still playing. A slight furrow of concentration marred the jade-like expanse of his brow, though his hands remained graceful and sure on the strings. Golden candlelight gilded his skin and painted deep shadows along the curve of his throat and the undersides of his wrists. 

Wei Wuxian’s hands itched for paper and ink, a familiar desire that brought back memories of a peaceful, sunlit library. Back then, his most pressing concern had been getting Lan Zhan to look at him. 

As though attuned to his thoughts, Lan Zhan lifted his head and looked at Wei Wuxian. “You should concentrate,” he said. 

A small, shameful part of Wei Wuxian urged him to just play along, snatch every shred of Lan Zhan’s presence while it was still on offer. And the music did help, a little — he felt as if he’d spent a day in meditation instead of an hour. But after months spent soaking in the resentful energy of the Burial Mounds, this was still like trying to bail out a sinking boat with a rice bowl.

“It won’t work,” he said, as gently as he could. 

Lan Zhan stopped playing, and dropped his gaze down to his hands. “‘Cleansing’ is a difficult song. I lack practice. I will—”

“It’s not about the song, or about your playing.” Wei Wuxian stood up again, and shook his head. “But it’s fine. I’m fine.”

Lan Zhan stood up as well, his mouth thinning into something hard and stubborn. The furrow between his brows deepened. “Cultivating with resentful energy harms the body and spirit.”

Wei Wuxian sighed and scrubbed a hand across his face. “This again? I told you, I know, and I’m controlling it.”

“If you choose to continue with this method of cultivation—”

“I have to—”

“Then let me help you.”

“How, exactly?” Wei Wuxian demanded. He knew he was getting annoyed, and he didn’t want to be, not with the resentful energy barely leashed within him. And not when Lan Zhan was so clearly trying to be kind. But he was tired, and arguing with Lan Zhan was like trying to swim against a fast-flowing current. “Your music doesn’t work. And even if it does, will you follow me around with your qin so you can play for me every day?”

“Then come back to Gusu with me,” Lan Zhan said, stepping closer.

“Lan Wangji.”

Lan Zhan froze. He stepped back, and something in his expression shuttered. 

Wei Wuxian took a deep breath. Eased down his hackles. “We’re in the middle of a war right now,” he said, when he was sure that his voice no longer sounded like an unsheathing blade. “Neither of us can go to Gusu anyway. Besides, what can the Cloud Recesses offer me that its preeminent disciple cannot?”

He tried a smile, and made himself hold it until some of the tension bled out of Lan Zhan’s shoulders. His eyes were faintly red-rimmed. Wei Wuxian had thought that he’d simply risen unusually early, but now he wondered if Lan Zhan had perhaps not slept at all. 

“The library,” Lan Zhan said. 

Everyone knew that Gusu Lan had the most extensive library in the cultivation world; it was one of the reasons why their lectures were so sought-after. Wei Wuxian, of course, had not been permitted access to any of the more interesting books except when under the hawk-like scrutiny of Lan Qiren.

He had heard that during Wen Xu’s attack, while Lan Qiren and Lan Zhan had led their disciples to safety, Lan Xichen had personally rescued centuries-worth of priceless texts before going into hiding. 

“I doubt even your library would have books about demonic cultivation,” Wei Wuxian said. “Remember Old Master Lan’s reaction when I brought it up in class? Though that might have also been because I was the one who brought it up. I never knew what his problem was with—”

“Wei Ying,” Lan Zhan said quietly. “Why won’t you let me help you?”

Wei Wuxian smiled again, somewhat less successfully this time, given the way Lan Zhan’s jaw clenched. “What do you mean? I let you in, didn’t I?”

“Wei Ying.” 

The weight of that fathomless gaze was suddenly unbearable. Wei Wuxian looked away. “Lan Zhan, I appreciate you trying, but you can’t help me.”

There was no reply. Wei Wuxian considered the possibility that he might have actually won their argument, finally convinced Lan Zhan that he was beyond saving. The victory felt as hollow as he’d expected.

“I can’t help you,” Lan Zhan said, slowly, deliberately. “Just as you have to continue with demonic cultivation.”


Panic crept its tendrils up the back of Wei Wuxian’s neck, closing his throat. He swallowed hard, tried to think of something to say, anything, to get Lan Zhan to stop staring at him like this— 

Well, the best military strategists would say that sometimes, the best way to mount a solid defense was to attack. 

Wei Wuxian met Lan Zhan’s gaze squarely. “No. Like you said, resentful energy harms my body and spirit. So unless you’re willing to dual cultivate with me and share yours, there’s nothing you can do.”

He braced himself for Lan Zhan’s fury, for disgust, for Lan Zhan to sweep out of his room and never so much as glance at him again. 

Instead, Lan Zhan’s eyes sharpened, his beautiful face lit with surprise. “What do you know of dual cultivation?”