Tbh I feel like if you wanna have an interesting discussion you could compare JC being a parental figure to JL to LWJ being a parental figure to LSZ. I think there is a rather big narrative parallel here.
Both JC and LWJ didn't have nurtuting parental figures as kids: JC with his abusive mother who fed into his insecurities and a dad who didn't really care to show him affection.
LWJ's dad was basically absent, and never showed up for his kids. His mom was barely allowed to see him, and it's the only bit of parental love we get to see him experiencing. And even that little comfort he loses at the age of 6. He has his uncle but from what we get to see in the book, LQR doesn't provide him with emotional comfort, too locked on the idea of raising a perfect gentleman who won't repeat his father's mistakes.
Both JC and LWJ have an older sibling they are close with who tries to compensate for the lack of nurturing parental influence to the best of their abilities.
So, both are traumatized by their families. For JC we see it in a way he can't form friendships, him often being rude and literally not being able to say a single good word to WWX who is lowkey his only friend (if you think about it, wasn't it one of the reasons JFM brought him in? So his son would have at least one friend). Him constantly being compared to WWX and pushed into a competition, feeling like he is not enough and never will be enough to be a family head etc. His inability to process his emotions whether positive or negative and constantly jumping to anger. Him clearly lacking emotional connection and clear wish to experience affection from both his parents. His upbringing absolutely has a huge effect on his personality and behaviour further on.
With LWJ I think we can clearly see that he just didn't have a childhood as a period of life. WWX notes multiple times how LWJ hasn't tried A LOT of the things that WWX marks as default childhood experiences (playing, creating mischief, having small wishes like trying a candy), LWJ's whole childhood was about studying and following the rules. Your grades are good? You get to see your mom. Your grades are bad? Welp, try better next month. I keep thinking that considering he has lost his mom at 6 yo, he must have been facing this treatment from at least since he was 4? Like. I wonder, if little Wangji spent years thinking that his mother's death was a result of him not studying enough but it's a topic for another conversation.
Either way, it's clear that LWJ is having a hard time processing his emotions as well as talking about his feelings which tragically plays a part in his relationship with WWX in the flashbacks. He also has a hard time allowing himself to talk about the things he wants which WWX notes in Yunmeng extra "You've really been like this ever since you were young, holding everything in and never saying what you want".
Both JC and LWJ abruptly have to become caregivers to the children who are not theirs. Both kids are orphans, both are the only connection these characters have to their dead loved once.
With JC and JL you can see that although I think he loves JL a lot, JC continues the same line of bad parenting he has experienced. He is constantly verbally abusive to JL, he barely says any good word to the kid wherever we see them interacting. He is emotionally unavailable for JL, he doesn't provide the warmth that JL so desperately need. If I remember correctly, JL even has a moment where he notes that he isn't used to being hugged and I think that in a way it's a parallel to the moment in the sequence where JC sees his father holding newly arrived WWX in his arms and thinks that he can only remember a handful of times when his dad would hold him like this. It feels like when JL needs some emotional support and understanding, he would rather run to JGY.
JL is still being pushed into being the best and over-achieving ("find the monster or don't come home" moments we see). Even if JC doesn't really mean it and it's "just his way of talking", we see that JL treats it seriously and endangers himself quite a couple of times. For example, on Mount Dafan or with the Human-Eating Fortress. Like these were near death experiences! If WWX didn't intervene, the kid would likely be dead trying to prove that he can handle a foe who is very much above his level. Regarding Mount Dafan, I think an interesting detail is that JL, unlike the Lan juniors, had an alarm signal on him to call grownups for help, yet he didn't use it. That could have very much cost him his life yet he didn't want to call his uncle because even though JC would absolutely run over to help him, he would also not loose his chance to berate him while doing so. That's pretty serious, you know.
Additionally, JL has a similar trouble of building friendships and connections to other people because verbally he talks very similarly to JC and it's a problem! This kiddo is very lonely and he doesn't have his WWX who would eat whatever mean thing comes his way because what else should he do. Like, JL is a good kid. He is smart, he has a good heart and a good sense of right and wrong but nobody will be there to see that if he will continue following this pattern
And I think you can find a lot of comebacks to these points when you look at Lan Sizhui even though I'd say we don't see LSZ and LWJ having an explicitly family-like relationship (aka we don't see LSZ calling LWJ "baba" or whatever xD), but you can feel that these two have a good level of trust in each other! LSZ isn't pushed into over achieving even though he is a good student, LWJ's perspective on that is summerized by him saying "do your best but not overexhaust yourselves" to the juniors. LSZ isn't afraid of making mistakes, he knows that he (and the other Lan juniors under LWJ's care) will not receive an unfair punishment under his watch. LSZ knows that he can ask for help if he understands that he won't be able to deal with a problem himself and he needs an adult, which we see in the Mo Manor when he uses signal flare to call LWJ. There is no fear nor hesitation from him of other Lan kids in regards to whether they should disturb a grownup. There is no reprimand from LWJ's side when he arrives to help. The kids don't need to unnecessary endanger themselves to prove a point.
You can also feel like LWJ subtly closes his eyes on some of the things that the juniors do even if it's against the rules if it isn't smth critical. He gives them the opportunity to experience a bit of freedom when they are outside of CR. You can see that he has probably reflected on the fact that he himself didn't have this freedom.
Returning to LSZ, character wise, LWJ did a pretty good job of raising him: the kid is good-hearted, polite, pretty emotionally intelligent, unjudgemental and ready to help those in need. Again, we don't see it "on screen" but we can understand that it takes a lot of emotional involvement, care and willingness to examine the shortcomings of your own childhood to try to change it and try to raise a new generation that hopefully won't have to go through the same pain.
