One of my favorite subtle moments of MDZS that I never see anyone else talk about is that section near the beginning of the book, during the Mo Manor arc, where WWX makes the active decision to help the Lan juniors
Because he takes a moment to think about it and articulates, for possibly the only time in the book (the only time I recall anyway), that he has valid reasons to hate the Lan sect - to the point that it would make sense for him to seek retribution.
The Lans were part of the ambush at Qiongqi Pass. The Lans celebrated Wen Qing and Wen Ning (really just Wen Qing but wwx doesn't know this) being burned and their ashes scattered so they could never reincarnate. The Lans declared war on WWX and the people under his protection. They participated in the raid on the burial mounds, slaughtering the elderly and the young (as far as wwx is aware. He doesn't know a-yuan was rescued) and drove wwx to his own death.
And for just that brief moment at the beginning of the book, before we the reader know any of the context, he acknowledges this. And we see him consider leaving. He could just walk away from Mo Manor. He wouldn't even be hurting anyone himself, he'd just be removing himself from the situation, leaving them to die.
But he doesn't. Because he decides that the juniors aren't responsible for the wrongdoings of their elders. They were just children when died. They've done him no wrong. So, at risk to himself, he jumps in to help.
Which, on it's own, isn't actually a huge thing? At this point in the book we still think he's a villain. So in the moment we go "so he draws the line at harming teenagers. That's interesting. Good to know" and we move on
But in retrospect? Even though WWX insinuates that he's ONLY helping the Lan juniors because they're young, and it would be a completely different story if they were adults, THIS IS NOT TRUE.
In fact, during the second raid on the burial mounds? The cultivation world AGAIN calls for his head on a platter. They blame him for things he didn't do. And then they're powerless. Powerless and under attack. and once again, wwx could just. Go. Just like at Mo Manor. Lwj still has his cultivation and his sword so they could just fly away.
But they stay. And wwx doesn't just choose to fight, he paints a lure flag on his chest and presents himself as bait. He puts his life on the line to save a group of people who celebrated his death and would happily see him dead again
So yeah. I love that moment at the beginning. He was summoned back from the dead to get revenge for Mo Xuanyu. He acknowledges that he has fair reason to seek revenge of his own. And in that moment, he tells himself that he's only helping because those teenagers, specifically, are innocent. And if they weren't teenagers he'd let them die in revenge. But he wouldn't. When put to the test he DOESN'T. Because when when Mo Xuanyu summoned the most evil person he could think of, a demon sure to seek revenge, he summoned the wrong man