A/N: This idea possessed me, picked me up by the scruff of the neck, and shook me until I wrote it. I seriously considered calling it "sometimes a blood-drinking session is the closest thing you get to therapy and a hug during wartime: the fic".

The title is from Lazyboy Empire's song "Vampire", and I listened to Ellie Goulding's "Keep On Dancin'", Ursine Vulpine & Annaca's cover of "Wicked Game", and Taemin's "Heaven" while writing.

It was a curse, they said. Cast by a cunning Wen cultivator in the moment before his death. It could be broken – they hoped; until then, it must be managed. Appeased.

(Sated.)

And it must remain a secret. No-one could be permitted to know that Zewu-jun had fallen prey to – this. They did not have to spell out why. Jiang Cheng knew exactly what a symbol of hope Lan Xichen was: unstintingly compassionate, single-minded in his purpose, effortless in its execution.

He wondered what it felt like, for someone like that to be brought to this. To be reduced to a bodily need: to be reduced to one's body. Did Lan Xichen's hunger feel like the emptiness Jiang Cheng had felt, a black, hollow pit, like the tolling of a silent bell?

It was hard to imagine Lan Xichen blood-thirsty.

And it must remain that way, to everyone save a few. Lan Xichen had to feed regularly, and often, if he was to keep from taking lives; Lan Xichen had to feed secretly, and on as few people as possible. That meant feeding on only the strongest and most trustworthy – most trusted – cultivators, those Lan Xichen already had no choice but to trust. Who better than the sect leaders who were his fellow-strategists?

It was a small circle, even now that Jiang Cheng was part of it.

After the initial horror, there was something strangely reassuring about the whole thing. Jiang Cheng felt constantly that he was fighting with one hand tied behind his back – too young to lead a sect, his following too few even to be called a sect, his brother and head disciple… missing. But Lan Xichen's survival was dependent on his drinking human blood. Nie Mingjue's cultivation was working overtime to recover from near-constant blood loss. There was a grim camaraderie in sharing this burden, in knowing that none of them was fighting with all limbs free.

Still, he was… nervous, now, standing in his quarters and waiting for Lan Xichen to arrive. It wasn't as if he could fail at this. All that was needed was for there to be blood in his veins. But the thought of someone coming close enough to get to a vein… that made him cold with fear. Chilled his blood.

He would not show that fear. He would not. He could not bear it.

It's for the war, he thought. You're doing this to end the war sooner. To end the Wen. To find Wei Wuxian, and there it was, the rage he relied on. He no longer felt the emptiness of being without a core. Instead there was a pitch-dark fire in the pit of his stomach, burning through his limbs. Clearing his head, burning away everything but what he needed to do.

A quiet knock. "Come in," he said.

Even now, Lan Xichen was beautiful. Back when… before, his beauty had struck Jiang Cheng like a blow; now he noticed it only as if through a thick sheet of glass. The fury in his gut, blazing like pitch, burned away all such things. But for all that, despite his new, near-deathly pallor, Lan Xichen was no less breathtaking.

"Jiang-zongzhu," he said.

Jiang Cheng turned to face him better. He did not know what he should do, or say. "Zewu-jun," he said, inclining his head.

"I thank you," said Lan Xichen, "for your kindness, in this. Not everyone would do what you have agreed to." His voice, always level, was a little quieter than usual, as if in recognition of the late hour. It was the closest Jiang Cheng had heard him come to sounding weary.

He stepped back, inviting Lan Xichen to come further in. "There is no need for thanks," he said. "It's only what I should do, in circumstances like these."

The words came out sounding blunt, though he had meant them to be sincerely courteous. This always happened when he felt unsure of his ground. "How should we do this?" he asked, before Lan Xichen could be… gracious at him again. "How is it… usually done?"

Lan Xichen stepped a little closer, his Gusu silks shifting around him in a pale blue cloud. He said, "It is best done either lying down or standing up. Sitting can cause difficulty with the angle." Simple and to the point. "We can do whichever you prefer. If you wish to stand, it is better to stand against a wall. It may… affect your balance."

There was really only one choice. "I'll stand," Jiang Cheng said.

Lan Xichen nodded. After a moment, he opened his palm, as if to indicate that Jiang Cheng might choose which wall he preferred.

Jiang Cheng began to move backwards, thinking to put a wall at his back. Almost immediately he felt foolish, stepping back without being able to see what was behind him, but there was nothing to be done about it. Half-defiant, he held Lan Xichen's gaze.

He settled in place, feeling the press of the wall at his back. Lan Xichen began to move towards him. As usual, he seemed to glide rather than walk. He did not move fast, yet there was a sense of swift grace about him; he was not slow, yet his gait was like that of a hunter, approaching with care.

Don't think like that, Jiang Cheng told himself.

Lan Xichen's eyes were very dark, now, in the pallor of his face. Their gaze was more fixed, more… focused, than Jiang Cheng had ever seen.

He felt his heart prepare to race. Consciously, he slowed his breathing. He could not put words to how that gaze made him feel: it made his skin prickle. He was suddenly very aware of his skin, as a covering, a tenuous shield, a point of touch.

Very gently, Lan Xichen reached out – slowly – to move the curtain of Jiang Cheng's hair away from his neck and shoulder. Jiang Cheng felt it brush over his shoulder, through his robes; felt Lan Xichen's hand brush against his neck.

He breathed out slowly, suppressing a shiver. That brief moment of touch –

Jiang Cheng refused to think about it.

Lan Xichen looked up from where his eyes had been fastened on Jiang Cheng's throat. They had said that only the jugular vein would do, for this. "Do you consent?" he said.

Even like this, even now, his voice was still faultlessly gentle. Kind.

"I haven't changed my mind," Jiang Cheng said, and then: "Zewu-jun," to take the sting out of his words.

Lan Xichen met his eyes. Nodded.

Bent his head.

Bit down.

First, a thin, piercing pain, two slow needles. A harsh intake of breath. Then: "Ah," Jiang Cheng breathed, halfway between a sigh and a moan.

All the tension seemed to go out of his body at once. The world was dark, and silent. There was only the place where hot blood met that cold, cold mouth; where all his nerves sparked and lit up in a sharp blaze of sensation.

It was good. It felt good. His body was dark and still, lights out. A thread of pleasure-pain wound through his veins, a glittering ache as keen as arousal, but it had nowhere to go. He might as well have been asleep.

Every muscle relaxed, he swayed against the wall, and felt Lan Xichen's hands tighten to steady him. Like this, he could feel everything. The air, cool against his living skin; the softness of his inner robe. Lan Xichen's hands at shoulder and waist, strong but not ungentle, holding him in place.

Lan Xichen's mouth, sucking at his jugular. Soft – even when drawing blood – but hungry.

He felt his arms come round Lan Xichen to hold him there, loosely, resting at Lan Xichen's shoulder, his back. He wanted… He wanted to cradle Lan Xichen and keep him there. To enfold him in the cradle of his skin and his blood, in this dark, hot space. Stay here. With me.

Here, where they were both safe. Where all he had to do was be still, pliant, and let the blood flow, let Lan Xichen take, and take, and take…

Lan Xichen pressed in even closer, and Jiang Cheng's body seemed to curve around him, to welcome him in. He felt Lan Xichen's hair brushing against his shoulder, those hands supporting him. Gentle and close.

Those hands. That mouth, tender, insistent, drinking deep. Something about it made Jiang Cheng want to cry.

He stood there in a strange, waking slumber, every limb aching with pleasure-pain, every nerve alight with that closeness. Body curled around the man drinking from his throat, drawing out blood and more of those long, sighing breaths.

When Lan Xichen finally left him, laid down on his bed, sleep came quicker to him than it had in months.

Lan Xichen walked away from Jiang Wanyin's quarters, sated.

It had worked. Jiang Wanyin was a strong cultivator: he would recover while he slept, his sharp-edged features smoothed out into peace. And Lan Xichen felt life in his veins again, felt that perfect calm that came with full, perfect energy.

There was relief in it, but there was also clarity. He could think clearly again, and that meant… disquiet.

This curse was a curse of hunger: the hunger the dead could feel for the living, for the life beyond their reach. Given time, and a lack of ready blood, it would weaken him. But even without that, it afflicted him with a constant, all-consuming feeling of hunger.

He had already felt… troubled… at the sight of Mingjue, his oldest friend – strong, loyal Mingjue – baring his throat. At what that made him feel.

Jiang Wanyin was something different. His face and voice could cut glass, and yet he swayed into Xichen's hold at the first moment. Xichen had no defence against that kind of… yielding. The pleading arch of his throat. When Jiang Wanyin breathed out, so close against him Xichen could feel his chest move, his every breath sounded like a moan of relief.

The night air was cool around him. Xichen embraced the feeling, and the sharp light of the stars. They could centre him in the present moment, if he let them, away from… other thoughts.

He knew what to do with hunger for the unattainable, with desires that could not be fulfilled. You settled into them, and let them become a part of your calm. You knew they were there; you knew you could not act on them; you knew they were powerless to truly act on you.

And so the surface of the water calmed. The pangs of longing became part of the silent tapestry of your life, and your head cleared. Lan Xichen knew this process well.

And still.

He suspected Jiang Wanyin would bring him no freedom from hunger.