Lan Wangji's talking robe
Lan Wangji's sleeves are the most perfect example of hammer space and I will not be accepting feedback. It is therefore the next logical step that, one day, Wei Wuxian just sets up a whole ass workshop in there. Which resulted in the occasional explosion out of a sleeve followed by a disembodied "I'm ok!"…
Sooner or later Lan Wangji accidentally on purpose brings the robe with his husband inside to a Discussion Conference. Suddenly the disembodied voice of the Yilling Patriarch is loudly providing commentary on the inanity of the speeches by different cultivators and sect leaders. No one can figure out how he does it.
Lan Wangji manages to keep an entirely straight face during the whole thing, until the mysterious voice starts going on about how the Chief Cultivator is clearly better than everyone else in the room because he's so perfect.
(Bonus points if it happens before they actually get together, but Wei Wuxian got caught up in his ranting and inevitably his brain switched to the "Lan Zhan! Lan Zhan! Lan Zhan!" channel.)
Obviously he needs to make sure everyone else knows exactly who they're dealing with. Clearly the Chief Cultivator is so much better than all of them put together, so much more attractive and talented and generally amazing, so really they should all be on their knees bowing to him because they're really not worthy of being in his presence, and yes Jiang Cheng, that includes you, stop scowling.
Wei Wuxian can't actually see out of the sleeve, he just knows Jiang Cheng that well. But Jiang Cheng doesn't know that for sure and he's half convinced that Wei Wuxian is somehow hiding underneath Lan Wangji's table. Yes, those tables are tiny but Wei Wuxian is skinny and Jiang Cheng grew up with him, he's probably seen him try to contort himself inside weirder places.
(This is also the first recorded instance of Jin Ling calling him uncle in public because the teenage need to make his embarrassing relative shut up trumps any hangups...)
Jiang Cheng would also not be surprised if Wei Wuxian had invented a talisman purely for the ability to hide under Lan Wangji's table and be shameless during conferences. Although he has to admit, Lan Wangji's ears slowly turning magenta the longer Wei Wuxian talks is somewhat entertaining. Better than whatever sect leader Yao was blathering about anyway.
Jin Ling eventually plucks up the courage to ask if Wei Wuxian would pull the same stunt on some of his meetings with the Jin elders. And that's how Wei Wuxian invented a paperman that can talk. His nephew asked for his help with a prank. He's never been prouder. The Jin try to ban Wei Wuxian from Koi Tower but Lan Wangji keeps sneaking him in inside his sleeve. And they can't really ban the Chief Cultivator....can they?
As always co-authored with/enabled by @sswangxian