5, 7, 18, 20 for chengning (but feel free to ignore any you don't feel like answering)
Hi Pallas! I'm always down to talk about chengning!
5.) What do they need to better themselves as people first?
Haha, I actually think they need to get slightly worse in order to get together post-canon! Wen Ning has to give into his impulsiveness and Jiang Cheng some self-harming tendencies so they can have bad idea hatesex.
Alternately, I guess maybe they could night-hunt with their nephews for long enough that they chilled out and got to know each other. But I think that could take a really long time... and how much time will Jin Ling spend in the field, anyway, now that he's a sect leader? Bad idea hatesex is faster!
7.) Could they have piqued interest in one another without said circumstances?
If they hook up at all, that's totally in spite of their circumstances.
I do think there's a universe (maybe Wen Ruohan choked on a grape and ate it when Wen Ning was a kid?) where Wen Ning got absorbed into Wei Wuxian's wider social circle and then got to know Jiang Cheng that way. I think I've seen this approach in a couple of different modern!au fics, where Wen Ning has the time to get over his crush on Wei Wuxian and then discovers that he likes Jiang Cheng.
Jiang Cheng strikes me as someone who doesn't necessarily like others easily, even as a teenager, and there's one adaptation (CQL) where the Wen sibling he notices is Wen Qing, not Wen Ning. He's someone who I think you need to hang around with for a minute before he warms up to you, plus Wen Ning is very shy. But also I think he'd be a sucker for someone genuinely extending him kindness, so if that happened...maybe!
18.) Do they love the real them or a mask? Both?
I think they hate each other for their mutual history, which is as close to emotional intimacy as either of them have gotten since both their respective sisters died. We make do!
More positively, I do think that starting from rock bottom is the only thing that might compel Wen Ning to be honest, since when he likes someone he doesn't seem to want to express any of his negative feelings around them... and I think he has many more of those than he'd like. And from honesty, sometimes you can get to actual emotional intimacy! Sometimes?
So if they do love each other, it's from a place of real, ugly honesty. One of the things that I find interesting about their dynamic is that Wen Ning is more honest with Jiang Cheng than he is with most other people. He's not, like, nice about it. But he's communicating! Which is more than Jiang Cheng is getting from basically anyone else (cough cough, Wei Wuxian)! Wen Ning gets someone he can be direct with and Jiang Cheng gets someone who isn't going to bother to lie to him. (As always, Jiang Cheng is very miserable.)
20.) What experience do they share only with each other?
Being the unwilling science experiments of Bad Idea Genius Team Wei Wuxian and Wen Qing. Looking at the other with Wei Wuxian and thinking, God, he loves him so much, look what he'll do on his behalf. You know, normal stuff!