"Only Lan disciples may enter. Wait here quietly or go back to bed."

"What? May enter where? That's so impolite, Lan Zhan, I thought the Lan Clan was supposed to be inviting. You can't just go in there without me, we're working together."

"We are not." He steps forward and vanishes into the blue air-shimmer.

Wow, he's been betrayed. Wei Wuxian should probably stop setting himself up for failure by pretending that Lan Wangji doesn't hate his guts, but unfortunately Lan Zhan is right in the center of the only interesting things that are happening.

Wei Wuxian stomps his foot. "Lan Zhan! Can you hear me? Lan Zhan? Fine, if you're too lazy to figure out a way for me to come with you, I'll do it myself. I got through the ward on your Gate, remember? I can probably get through this one too, if you just wait for me."

...oh no. 

If the ward is broken, Uncle or Xichen will know. Then he won't be able to pretend that he found the Yin Iron here by accident.

Lan Wangji reappears on Wei Ying's side of the ward. Slaps his hand down, where it was about to draw a sigil in the air. "Behave."

"Will you -"

He pulls his headband loose and loops it around his wrist, then Wei Ying's. He doesn't think anything about this at all. He definitely does not think about the last time they did this, when he'd been afraid that Wei Ying could hear his heart beating too fast and afraid to be bound in any capacity to this wild, beautiful boy who he was terrified of and not yet in love with. 

This time, he is in love with him. Still terrified.

He gives Wei Ying a don't-mention-this sort of look and sees, in his face, how utterly insignificant this is to him. That's - fine. That's probably for the best. Together, now, they can walk through the ward into the Cold Pond Cave.

Cold Pond Cave: very cold. Impressively large, the high cavern ceiling dripping with stalactites and ice. The water that they now wade through is cold enough to be ice, but somehow isn't. Already, snow is somehow collecting on their hair.

There are rabbits, snow white and wearing tiny Lan headbands, apparently content to hop around on the snow and rock.

On a snowy stone platform elevated up from the icy pool rests a pristine white qugin that almost seems to glow.

How completely unexpected!! Wei Wuxian makes lots of noises, half of them sounding impressed and the other half sounding miserable and cold. He gasps and remarks and complains, but Lan Zhan already seems to be ignoring him again.

This is correct. Lan Wangji appreciates that he is being distracted from Wei Ying, even by discomfort.

The last time he was in this cave, he lay bleeding out into these icy, healing waters. Even though his wounds had never stopped hurting, the pain then had been truly unimaginable. Worse still, the pain of grief and his own failure. His love was gone.

The time before that, Lan Wangji had stood beside his uncle and listened to the awful, vivid sounds of butchery as members of his clan were slaughtered. Killed because of him, to draw him out. Their choked screams, and Wen Xu bellowing his name...

He makes it all the way to the qugin before he stops being distracted.

He sits. Shoos Wei Ying away from the heirloom, ignores his requests for an explanation, closes his eyes and begins to play Inquiry.

Grand Master. Please. I must speak with you. I want to help.

Notes begin to play on their own, in patterns he can interpret as meaning he's found the spirit he's sought.  

From seemingly out of nowhere, a woman appears.  She is dressed in the robes and headband of the Lan sect.  Her expression is subtle, but indicates just a trace of confusion as she greets them.

Wow What

Wangji tugs him out of her way and then kneels on the other side of the qugin, bowing deeply. "Grand Master Lan Yi. I am Lan Zhan, a descendant from the Lan Clan."

"Lan Yi? Lan Zhan - is that the same Lan Yi who -"

"Oh, ah -" He scrambles to bow appropriately beside Lan Zhan. "I am Yumeng Jiang Clan's Wei Wuxian. Master Lan Yi."

She takes a seat, bunnies flocking around her.  

"For what purpose have you come here?" she asks.  

The bunnies are so cute.

This is a lot harder to navigate with Wei Ying right beside him. "I know the Yin Iron is becoming unstable. Soon it will no longer be sealed. I want to keep it safe. With it I will find the other pieces and bind them here."

"Yin... Iron...?" Wei Wuxian is not following any of this and Lan Zhan has really let him down as a detective buddy. Exactly how much information is he missing, here?

"You seem quite young to have been entrusted with this.  And yet, what you say is true.  My power to contain my burden weakens by the day."  

She glances at him, and between them.  There is, ultimately, little choice.  Even now, the Yin Iron's resentful energy seeps away through the cracks in her barriers.  It is only a matter of time before the barriers fail entirely.  To pass on the torch to the next guard is inevitable, if it is to be guarded at all.

"Does the tradition passed down still speak of the dangers of the Yin Iron?"

"Wei Ying has not heard tell of them. It would benefit him to be cautioned."

Wei Wuxian looks affronted. "I'm truly sorry, Master Lan Yi, but I've never heard of a Yin Iron before." He elbows Lan Zhan. "Someone didn't tell me, even though I asked what he came here looking for."

"You do not need to know what it is. You only need to know that it's dangerous."

"Lan Zhan that doesn't make any sense."