I doubt anyone is interested but I always wondered why there is such a marked difference in character development b/w Xue Meng and Xie Xue , two characters who who are very shizun-con/brother-con , in a very similar way and have some sort of complex against the Gongs which prevents them from being friends( at different point of their arcs).
I think its about superiority v/s inferiority complex as well. XM looked down on MR from a place of superiority complex. He needlessly used to think he is better than him and hence CWN, someone he respects and considers above him is certainly above MR's reach to be respected too. That toned down later. The lesson seems to be that one can work on superiority complex if one tries hard enough.
Whereas XX comes from a place of inferiority complex. She thinks she is nowhere near capable enough as her brother, she certainly has done enough crap against her brother's wishes to exacerbate that feeling. Yet she feels immense emotional gratitude for being taken care of aka someone she puts on pedestal means she would never direct the resentment of feeling inadequate against him. She finds HY's ingratitude in her eyes hence extremely discomfiting, since in her eyes HY has always been younger and unequal.
So watching someone like that who on paper is superior to her to, gain a higher moral ground in that video leak incident pissed her off even more. Her already existing terrible inferiority complex hence increasing. To find out later that HY may or may not have forced himself on XQC which made her feel "relief" could be both homophobia and her feeling better about her own self after the video leak episode made her unconsciously feel bad about herself.
I think this is why XM's overall attitude about image narcissism remains the same whereas XX is practically unrecognizable from her first appearance. This is why she has no emotional incentive to change how she looks down on HY unlike XM, who found it more emotionally rewarding to let go of some his superiority complex against MR. XM gains a friend this way.
However, much to XX's chagrin, not only HY not change unlike MR in her eyes but he still "gains" her brother anyway despite being worse than her in her eyes. So she her attitude of resentment hence more or less remains the same. Hence her continues childish/petty attitude in her head even when HY was suffering depression on what he thought was period when XQC had died( "I just call him when I miss him" ...girl wtf)