Following the "JGY forces LWJ and QS to marry after have set a trap for LWJ and Rusong kills WWX"
**It's his father, LWJ, that catches him in the act. He smiles upon seeing him. Now everything would be fine, he killed the miscreant that was bothering him. A demonic cultivator, a cutsleeve lunatic, the murderer of 3000 men. Perhaps he'd finally be proud of him, for once.**
And Rusong loses any chances to be ever liked by LWJ.
LWJ will not hurt a kid, but he's dead to him. He doesn't even look at him anymore. Rusong doesn't exists for him anymore. At least, before, he acknowledged his existence but not anymore.
Rusong loses all the rights of a Lan heir, he's even less important than any disciple now. A lot of disciples, who were jealous, speak about him behind his back because he loses his father's favor.
He says that he killed WWX but nobody believe im since oly LWJ has seen him. Afer all WWX has been dead for years, right? People laugh at him because seriously what this kid invent to have his father's favor. Because even if WWX was bring back to life, a 15 years old couldn't kill him, really. LQ tells him that lies are forbidden. Xichen looks at him with deception (because he knows, he knows that Rusong killed LWXJ's true love)
QS looks at him with dissapointement. Because over the years, her and LWJ have reached a kind of friendship and she knows. She can't blame her child but...
He doesn't understand. He feels even more unloved than before, because he doesn't even exist for LWJ anymore, he feels not welcomed to CR anymore. LWJ makes him feel like he's better to go away. Shizui is now the real heir until xichen got his own kid.
Shizui is furious over him because he remember WWX, and turn his back to him at his turn.
NHS screams with frustration. His plans are going to all without WWX. A very loyal and strong Nie disciple sees that the plan to avenge Nie Mingjue (who saved his life) is going to fall, leaving JGY in control. NHS has a copy of the ritual, thank to Mo Xanyu so he decides to do it. Without any demands. Just a letter begging to help his sect leader to avenge Mingjue. NHS is devasted, he didn't want his disciple to do that, but now WWX is came back in a body of a 27 years old, strong, with a good golden core and he even look a little like he looked when he was alive. Except his eyes who are green.
LWJ recognize him by hasard, because of the song, agaibn.
Everything happens like in canon after that, everyone think "aww LWJ find a friend with who do night hunts =)"
LWJ doesn't want to lose him again so this time he says his feelings and they become a couple before they found Mingjue's head.
During the escapade at the golden tower, WWX realize that JGY plans to get rid of Jin Ling, who is the Jin Heir, to put his own son (he got married at a point) as sucessor. JGY can't proove that this Nie Disciple is WWX since he has his own sword and so he's not using Subian in self defense (and he uses traditional cultivation, since he has a strong golden core). so he tries again, and again, but the duo WWX and LWJ sucess in everything and NHS plays his cards when everyone (for reasons) is reunited to LP and all the truth explode.
Rusong is actually his son and he has trapped LWJ so he'll marry QS
Because QS is his sister.
Rusong is a incestous kid
JGY killed Mingjue by poisonning his mind with musical cultivation.
JGY panick and the events of the temple happen. Rusong hears his real bio father who tells him "'if my plan to marry LWJ and QS didn't work, it would have killed you" He also realizes that what he did, who make him lose any chance to ever be loved by LWJ (killing WWX), failed since WWX came back to life, again.
Nie Mingjue's body take revenge and everything end well.
Jin Ling is saved (because JGY really tried to kill him) and is now the sect leader. JGY's son is a 4 years old so he's not a danger for Jin Ling. And he's ready to open his heart to WWX since the man saved him few times and spoke with him about his mother.
NHS is satisfied. Now he can reveal how good he is as sect leader without fearing for his life.
Lan Xichen go in seclusion for 4 months then accept to marry. Since it's his duty. 1,5 years later, his wife give birth to twins. A boy and a girl.
Now that it's revealed the truth, LQ is agree to cancel the marriage between QS and LWJ, QS thank LWJ for his kindness over the years. She now want to travel with her son, sees the world. They leave the Lan Sect.
LWJ doesn't say goodbye to Rusong. Even if WWX came back again, he could have not. He thought to have lose him again, and he can't forget this pain. And for that, he can't forgive. Yeah he's petty. But losing WWX just atfer have him back was too much. Even if WWX came back again. He can't ever trust this kid again. Rusong is heartbroken, a smile is all he wanted from his father.
QS, with some luck, will find a man who will really love her and who is not her half-brother or someone forced to marry her. Since she is young and a cultivator, she can even hgave another child. Rusong must adapt to this new life, away of the man he thougth to be his father, away of the Lan Clan, away of all he thought to be his truth. His new father-on-law is nice, and give him attention.
LWJ go in a lot of hight hunts with WWX and Shizui who is overjoyed to have his A-die back again. In their night hunts, they adopt 2/3 orphans because WWX is a real mother-hen inside.
I honestly think Lan Wangji would throw the rule book at Rusong. Ensures the kid has a trial for murder and is imprisoned for life. People praise him and his dedication to justice, making his only son face consequences.