Wei Wuxian's first meeting with teenage Jin Ling just gets funnier every time. Especially because, by this point, he should have a rough idea of how long it's been since he died, and he immediately recognizes Jin Ling as a member of the Jin Sect, clearly an important one if he's bossing other people around and spending absurd amounts of money on spiritual nets. If Wei Wuxian had spent A SINGLE MINUTE actively trying to guess this kid's identity, he probably could have worked out that this kid has a high chance of being his nephew.
But Wei Wuxian does not take the time (thirty seconds! WWX, you could have made an educated guess!) to figure out this kid's specific identity! He's just been wrestling with an incredibly stubborn donkey all day and he's probably hangry again because they had to share an apple. He just thinks to himself, "Wow, this Jin kid is a real spoiled brat," and goes from there!
"Didn't your mother ever teach you any manners?" he says obliviously to JIN LING, his own fucking nephew. When Jin Ling is FAMOUSLY ORPHANED. Like, you could go up to literally anyone on the street and be like, "What happened to that rich kid Jin Ling's parents?" and they would immediately tell you, "Oh, the evil Yiling Patriarch killed them, evilly." Very high chance that no one has ever said anything like this to Jin Ling - extremely rich young master, most famous orphan in the cultivation world, in possession of some very scary uncles - before.
And from Jin Ling's perspective, this outrageous comment is coming from his OWN UNCLE, Mo Xuanyu, his late grandfather's bastard son who was kicked out of the sect for being gay and crazy. There is NO WAY that Mo Xuanyu could somehow not know that Jin Ling has no parents, so of course, this has to be an intentional low-blow insult bringing up and disparaging his dead mother. So, of course this brat tries to start a fight! Mo Xuanyu started it with words like that!
And then Wei Wuxian trips him and essentially sits on him (using a talisman), there's the whole "My uncle is going to kill you!" & "Who's your uncle?" exchange, and Jiang Cheng immediately interrupts them. And Wei Wuxian has to do the sudden, incredibly simple, damning mental calculation of: "Jin kid + Jiang Cheng for an uncle = Oh, fuck."
It's funny every single time.