So in this au MXY is not thrown out of the Jin Sect as he ends up knowing a bit more about demonic cultivation and JGY thinks he's useful.

The story is set about 6-7 years after WWX's death, so Jin Ling is about 7 (turning 8), MXY is about 20ish, XY is also in his early 20s. JGS is already dead, and so is NMJ. Madam Jin is still kicking tho.

XY was a guest disciple (under a fake identity) at Carp Tower, together with MXY they both secretly learned demonic cultivation, thus growing somewhat close (MXY might or not have developed a crush on him). MXY was in the dark about the reasons for studying demonic cultivation, he never really put in pratice just passed his notes on to JGY. XY, of course was in much more deeply. And although he quite enjoyed the job and his position he and JGY started disagreeing quite often on how to do things. So one day XY decides he's had enough, he makes a really frightening proposition to MXY, as he's the closest thing XY has to a friend, but MXY doesn't agree and has the gall to look frightened?! XY makes a mess then leaves.

He goes to Yi city and there it develops much the same, except he doesn't have time to kill A-Qing because JGY is on his ass. (JGY basically decided XY was too much of a liability if not working for him.) Unluckly for everyone had managed to pocket part of the Yin Toger amulet so he makes a run for it and disappears for a few years.

Filled with rage, A-Qing swears revenge on XY. Xue Yang didn't manage to get to her so she still has her sight and speech (the last one maybe a bit affected after the tragedy). A-Qing doesn't know how to cultivate so she pockets Xue Yang's notes and learns demonic cultivation. She manages to get some conscience into Song Lan while trying to learn to control him. They become a bit of a master student duo, SL teaches A-Qing fighting and the basics of cultivation (she's very very bad at it) and tries to steer her to a less murderous/revenge filled path. They argue a bit because A-Qing says she can never forgive XY and won't give up on her Gege (Xiao Xingchen's souls fragments they try to collect)

Going back a bit, the reason MXY is better at cultivation is this au is because of...Jin Ling? Ok so I decided this au was not messy enough and decided to merge it with ghost WWX au.

Basically WWX becomes a ghost, he does not know how (JL accidentally summoned him) and he know the right thing to do would be to just leave as to not cause more unecessary trouble but...he just can't. He misses his family guys. A lot. He starts kinda haunting Lotus Pier, makes his demonic energy intentionally very low wich makes him quite weak and barely visible even to cultivators (if it was his normal levels it would be instantly noticeable who he was, it's that strong). He's constantly on the piers, hiding, sometimes he visits Shijie's and the previous leaders graves(?tombstones? forgot the word in english) asking why him. Nobody notices him, and then well, Jin Ling does.

He's about 5 and everyone kinda dismisses him as having a ghost living in a cultivation sect is almost a joke and nobody thinks it too possible. And even when they check WWX just evades them making Jin Ling angrier. So he gathers all his courage he goes to confront this ghost. He can deal with this ghost, he's the heir to the Jin Sect after all. Plus defeating a ghost will definitely make JiuJiu proud. WWX does not in fact want to engage him. So it starts their cat and mouse game.

At some point Jin Ling tires WWX enough he gives up and asks him what he wants.

JL: As the future leader of the Lanling Jin Sect and Yunmeng Jiang's Sect Leader's nephew I command you to leave! You evil ghost!

WWX: Hmmm, no. I don't wanna.

JL: YOU CAN'T DO THAT!!!

So Jin Ling starts hanging out with this ghost, to totally find a way to exorcise him and not because he couldn't make any friends his age and Jijiu is too busy for him and he's lonely. WWX does not tell him who he really is, but starts kinda mentoring Jin Ling or just being supportive and trying to get him to loosen up a bit and have fun. He ends up having to use a bit of demonic cultivation to save Jin Ling a few times (the child is a menace). He teaches Jin Ling the basics but nothing like controlling corpses, just stuff thats somewhat accepted by the wider cultivation world. Somehow his notes end up getting to MXY, by virtue of Jin Ling who decides MXY can help him learn if WWX won't teach him. MXY translates the notes and is a bit worried about how Jin Ling got them and also only teaches him the BORING and bare minimum stuff.

I've been writing so much, the whole thing's probably too convoluted. But basically the plot of this au would start with MXY having to protect Jin Ling as someone is trying to kill him, JGY does not in fact want to have another nephewbaby with his sisterwife so he wants Jin Ling to stay the heir. Jin Ling finds out about a mystery he wants to investigate to prove himself to jiujiu, and MXY is tasked to follow him so he doesn't get harmed and to do WHATEVER IS NECESSARY to protect him. In their way they run into A-Qing and Xue Yang (maybe Lan Zhan at somepoint) and the first climax of the story would be the trhee of them fighting each other: -Xue Yang wants to JL for blackmail reasons and to kill A-Qing

-A-Qing wants to kill XY for revenge, doesn't care about the kid, would use as bait

-Mo Xuanyu does NOT want anyone to die. Most of all he wants to protect Jin Ling but also can't get himself to kill XY

In the end the three of them get stopped by the grand master of demonic cultivation himself, who decides to intervene and kidnaps all of them since before they all get kinda get killed by Jin forces. Yes this was in fact a plan of JGY, he does not want to kill his nephew but doesn't mind causing him trauma. Basically he wants to kill three birds in one stone, getting rid of XY and grabbing the talisman, using that to send MXY away and then probably kill A-Qing and SL so nobody will know.