SVSSS AU where SY transmigrates while SJ is with Wu Yanzi after a qi deviation SJ has.
Wu Yanzi sees Shen Jiu after deviation is like 'welp no longer useful... i'm gonna trade him to demons for some useful artifacts' and Shen Yuan ends up in demon realm, and he is like 'Yes! You know what this is good away from death flags and look at all these awesome creatures'
The demons are just staring at this little cultivator who knows WAY to much, about beasts within the abyss, ancient artifacts that they thought lost forever about all different types off demons/creatures just far to much.
Collectively decide he's either a god or a seer or something... and maybe they should do something about it but... he's just...nice. To nice and also they don't want to end up accidentally killing a god and getting wrath of heavens turned on them.
So Shen Jiu is just freely roaming around demon realm and ends up bonding and picking up collection of little demons because 'Why are you dropping these poor kids in the middle of wilderness poor little buns'. He has baby Mobei Jun and Baby Sha Hualing following him around like ducklings and he totally uses knowledge of artifacts and plants ect to make sure the two are safe.
They have both has Shen Yuan for 5 minutes and if anything hurts their new big brother/father they will kill everyone here and then themselves.
When Tanlang jun is sealed away, Shen Jiu sees all the chaos and somehow ends up de-facto leader, especially cause he's like 'No Tailang Jun has an heir he'll show up eventually and you'll all be fucked so calm the down and play nice. He's just keeping things together easier for when Luo Binghe shows up cause he's protagonist sop surely he'll come for his birthright and hopefully because no SQQ there he'll have a happier childhood and hopefully a happier ending.
Things process with Luo Binghe ending up as head disciple of Bai Zhan.
Eventually there are rumors of a demon king who is not actually a demon and the peak are investigating when Sha Hualing does her invasion because 'Stay the fuck away from our Shen Yuan you cultivators' there's a huge fight and Shen Yuan ends up showing up with Mobei Jun (he told on her and teleported them there)
Everyone is shocked at this cultivator being in charge of them all and all the demons listening to him. And the wifebeam is in full effect.
Yue Qingyuan shows up and 'Xiao-Jiu??'he is awestruck his Xiao-Jiu is actually alive he's thought he was dead for years.
Liu Qingge is shocked at being saved by this random cultivator who is colluding with demons, but he whose him a debt as he saved him.
Luo Binghe is so confused this cultivator showed up saved him and knew his name. Called him Binghe and smiled at him. He has so many questions.
Mobei Jun and Sha Hualing are not happy at all. Well mostly Sha Hualing as Mobei Jun is distracted smitten with some random peak lord.
(Shang Qinghua has no idea what happened to his story Mobei Jun never showed up, no SQQ, where is his plot? his system is confused Shang Qinghua is confused...and for some reason he feels the urge to blame peerless cucumber)
Luo Binghe showing up in demon realm and like, demon emperor ok...does...does Shen Yuan come as empress?he's basically already running it that's part of deal right? and then has the entire demon realm giving him shovel talk because they all adore Shen Yuan.