I came up with a genius AU where Jiang Cheng fucks. Not for sect matters; just because he likes to be worshipped like that. So Wei Wuxian comes back to Lotus Pier after a full reconciliation thinking that Jiang Cheng is still a virgin and fully intent on making fun of that.
He gets dragged into a conversation with Lan Jingyi and Ouyang Zizhen (Jin Ling occasionally joining in, while Lan Sizhui pretends like he's not listening but totally is) about which cultivator fucks the best. It's a tie between Hanguan-Jun and Zewu-jun (because lets be honest: the Lans have monster dongs).
And Jiang Cheng, who was never supposed to overhear: sweet sweet Jiang Cheng, who has never even held hands with anybody and found even passionate gazes shared between lovers to be shameful; Jiang Cheng who couldn't charm a person if his life depended on it; this Jiang Cheng walks by, hears the conversation, and says with no hesitation:
"Neither of them, actually. Zewu-jun goes a little too fast, and Lan Wangji doesn't know how to tie the ropes properly. But Nie Mingjue does this thing with his tongue that you'd never have thought was possible."
And he simply continues on his way as if he didn't just completely shatter all of their world views by revealing that he, in fact, does fuck, regardless of what they previously thought.
Wei Wuxian drags him back in and demands to know:
a) why he knows how Lan Xichen and Lan Wangji fuck
b) why he knows what Nie Mingjue fucks like
c) why he knows about BDSM
and upon being given answers,
d) who he has fucked
And Jiang Cheng, bless his shameless self, simply replies, "Who haven't I fucked?" and goes back on his merry way, leaving the other 5 scrambling to figure out exactly how many people this man had fucked.
(spoiler: everyone on the Most Handsome Cultivators List and more)