In a way, in MDZS, Lan Sizhui is the key and answers to the big moral questions in the story: was it all worth it? Was it all worth it when Wei WuXian lost so much, even his life, when the Wens almost all died anyway, when there was so much collateral damage?
The narrative says: yes, it was worth it, because one child survived, and thrived. Look at that lovely, loveable young man! He is the reason all this was not for naught.
But what I find interesting is, Lan Sizhui is not even that exceptional, he doesn't make a big difference in the world, does he? He's still young, but despite his really good character and keen mind and aptitudes, he's not a genius, he's not renowned, he's not a Hanguang-Jun or a Yilling Laozu. He's just a kind, good-mannered, well brought up young man. Anyone would be happy to claim him as a son or a disciple or a son-in-law. But he's not some big game changer. Even though being a cultivator sets him apart from a good chunk of the normal population already, in his habitual context he's a normal kid. He makes friends, acts silly sometimes, hasn't slayed any Shuanwu of slaughter, got easily led into a trap by a trail of beheaded cats. A normal kid.
And that's important, because this reward is as the sacrifice Wei WuXian made. He didn't make some grand gesture for important people. He did what was right in his view, no more, no less. It wasn't for some greater good, even less for fame. It was simply what was right. And if you do what's right you're not really adding up and subtracting the wins and losses as in a giant thought experiment of the trolley problem. There probably would have been ultimately less death and suffering had Wei WuXian let the Wens to their misery and death quietly. There wouldn't have been a Lan Sizhui, but there would have been a Jiang YanLi, a Jin ZiXuan, and many people that got killed when they attacked him would have lived. But it wouldn't have been right, and so Wei WuXian doesn't think about it that way, and the narrative doesn't either. It tells you life is complicated, and sowing violence reaps more violence, and you can't always "win". But if you do your best, if you keep doing what's right, even if you are only human, and make mistakes, and everyone is against you, it still counts.
It counts. Not for the greater good, not for fame, it counts. Because the whole point is Lan Sizhui gets to live, and grow up, and be a normal kid and have a good life, and that's enough. He doesn't need to be or do anything "more" than that.
