The hall at the center of the Burial Mounds was huge, rough stone walls arcing away into darkness. Lan Wangji didn’t care what was hiding in the vast space; he had eyes only for the man floating at its center, surrounded by black smoke, writhing in it. The smoke was screaming.
Who are you? Why have you come here? Why are you hurting us?
"I have come for Wei Ying," Lan Wangji said to the voices in the darkness, to the smoke pouring over Wei Wuxian's body, to the army of ghosts that Wei Wuxian had inexplicably invited in. (Inexplicably? He had been in the Yiling Burial Mounds for two months now. Who knows what bargains he had had to make to live through it? Lan Wangji's heart ached.)
Wei Wuxian turned in the air until he faced Lan Wangji. His eyes were empty. Lan Wangji shuddered.
He is ours, the darkness said with Wei Wuxian's mouth. He will be the instrument of our revenge.
Lan Wangji's hand clenched in his sleeve, a cold rage pouring through him. Bad enough for anyone to claim ownership of Wei Ying, but an army of resentful ghosts? No. He summoned his guqin, Wangji, and played a chord that made the darkness scream.
"Let him go," he demanded with words and music both.
His fingers played over the guqin, summoning a music far more complex than the one he'd played to enter safely into the Burial Mounds' darkest depths. The smoke roiled faster over Wei Wuxian's body. The voice in the darkness shouted and then unraveled into many voices, decohering as the chords he played speared them through.
My revenge— My son— My love— I hate them— Blood for blood— Don't go— The dark— Sister— It hurts— Lan Zhan—
Lan Zhan? Lan Wangji's fingers slowed on the strings and then returned to the melody, interlacing the attack with sweetness and concern, all the feelings he had never told Wei Wuxian about, had hardly realized he felt until that moment on the road two weeks ago when he had had to face the possibility that Wei Wuxian was lost forever: when he had heard the whispered rumor that Wei Wuxian had been thrown into the Burial Mounds from which there was no return. Well, there would be a return for him. Lan Wangji would make it happen.
The smoke cleared and so did Wei Wuxian's eyes. "L-Lan Zhan?" he said, voice rough with disuse, and smiled uncertainly. Even now, Lan Wangji was struck by how beautiful that smile was. "What are you doing here? Wh- How?"
"Wei Ying. Come with me."
"But how did you get here? Lan Zhan, don't you know how dangerous it is?"
A part of Lan Wangji wanted to laugh at that, at Wei Wuxian warning him about the danger. He kept his face and voice even. "I walked and played." He caressed Wangji's still strings. "I played the wards open and the ghosts quiet, and I can play us out again."
"I—" It was an unusual experience, Wei Wuxian lost for words. Lan Wangji hated the waver in his voice. "I don't know."
"Come with me." And then, because coming here by itself had probably revealed everything he preferred to hide anyway, "Please."
"Then…" Wei Wuxian looked around the cavernous space with its history and its ghosts, then turned a smile on Lan Wangji so real and bright it made him catch his breath. "Okay. Lead the way, Lan Zhan. You know how?"
"Yes, I—"
Wei Wuxian cut him off, voice serious, almost didactic. "Don't look back and don't stop playing. The ghosts here have been lonely and hungry for so many years; the least distraction will finish us both. I'll be right behind you; I—” He paused for a long moment, struggling with words he clearly didn't want to say. "I'm very weak right now, so I'll be slow, but I won't stop."
Lan Zhan nodded firmly. He ran his eyes over Wei Wuxian: his gaunt, pale face, his ragged farmer's clothes, his still-bright eyes. He wished suddenly that he was more like Wei Wuxian, more able to say with words all the things he felt. He lifted his eyes to meet Wei Wuxian's. Wei Wuxian had been watching him, a half smile still on his face.
They nodded at each other once more. Maybe that was understanding enough. Lan Wangji turned toward the doorway and began to play again.
It was the longest walk of his life. The ghosts were ferociously intelligent. They realized quickly that their latest prey was trying to escape and they were furious. Lan Wangji felt his robe buffeted by no mortal winds; felt powers slam into Wangji, trying to wrench it from his hands; heard wails on the edge of hearing. Well, he'd learned long ago how to endure almost any trial. He would endure this.
A part of him wondered how Wei Wuxian was bearing up under such an onslaught, but he could spare no attention to anything but the instrument in his hands, the melody that would bring them safely through. He played on. The wails grew louder. He could hear words in them. They were strangers long dead, but sometimes they took on the voices of people he knew—Xichen, his uncle, his long-dead parents, the disciples he'd grown up alongside. Sometimes they screamed like Wei Ying in pain and that was hardest to bear.
He played so long that his fingers grew tired, hurting even through the callouses, until finally he could see the exit, the afternoon sunlight in the world beyond. Just a little farther, he thought and played on.
He stepped past the outermost ward.
And then, the worst possible thing, a scream of agony from Wei Wuxian, torn from his living throat. Lan Wangji whirled, eyes wide, the guqin falling to the ground in a discordant jangling of strings.
Wei Wuxian was clutching his chest with both hands as though to prevent himself from flying apart. He was shivering like he had in the Cold Spring; no, like a man with a fever; no, like a fly-stung horse. His mouth and chin were bloody, eyes red-rimmed. The fog of ghosts covered him so completely, it turned his farmer's clothes into a cloak of darkness. "Lan Zhan," he said weakly and tried to smile.
Lan Wangji stood rooted to the spot. He had no idea what his face was doing, had no control over it for the first time in living memory. He couldn't speak.
"Lan Zhan, I'm sorry." His voice was so weak it was barely audible, but Lan Wangji heard it, was already shaking his head to deny the words. How could Wei Ying be apologizing right now when it was Lan Wangji who had failed?
Wei Wuxian shook harder, his arms spasming around himself. He pressed on. "Lan Zhan, thank you so much for trying. It's the nicest thing anybody has ever done for me. I—"
"Wei Ying, no." Lan Wangji felt the mask of misery his face had become. "No, I—" Not taking his eyes off Wei Wuxian, he fumbled on the ground for his guqin.
But Wei Wuxian was smiling and shaking his head, the saddest smile Lan Wangji had ever seen. The ghostly fog was climbing his neck in a whispering mass. Lan Wangji had never known before that smoke could seem triumphant. "No, you have to go. But Lan Zhan!" he cried, as the black smoke spread over him, roiled faster. "I can save myself! I promise!" Then, he was gone.
Lan Wangji fell to his knees, staring back at the path under the twisted trees where he could see no trace of Wei Wuxian.
Eventually, he packed up his qin and returned to the war.
(One month later, Wei Wuxian returned, so changed he was scarcely recognizable as the young man Lan Wangji hadn't meant to fall in love with. Wei Wuxian's new magic and Lan Wangji’s failure in the Burial Mounds stood between them, an accusation that cut both ways. Lan Wangji's heart ached.)