How I think SJ and SY would meet if there wasn’t any sibling or Shizun/disciple au going on:
At Huan Hua Palace
Shen Yuan is a traveling renowned scholar. His name is known and praised in both the human and demon realms (he unknowingly helped Su Xiyan and Tianlang-Jun with their relationship and prevented the original disaster from happening so Tianlang-Jun sings his praises every time he shows off his wife and son.) he is also the third son of a noble family.
To sum it up, he’s a snobby self confident bitch. And no one can stop him.
Shen Jiu, as the head disciple of Qing Jing peak, has gone to Huan Hua Palace for a conference. It’s his first alone with no observations from his Shizun. He’s a bit worried, which just means he’s extra bitchy today.
Shen Yuan approaches Shen Jiu—with no clue to who he is or his status—because of the book he has in his hand. It’s one of his favorites. And this guy says he’s going to be speaking at the meeting he’s going to in order to discuss some points in it and relate them to current problems and make solutions. Shen Yuan is now actually excited about this meeting!
And then, halfway through a very interesting conversation with someone with actual brain cells (both of their thoughts) some Huan Hua disciple cuts in. He starts spouting some nonsense about how they shouldn’t be in this hallway and that if they didn’t leave he would be forced to remove them. Choosing to ignore the idiot, they keep on their conversation about the book in Shen Jiu’s hands.
Seeing himself being ignored for a book, the disciple decides to take it from their hands and go on his whole speech once again.
Big mistake.
Twenty minutes later, the Huan Hua disciple is covering his eyes and crying in a ball on the ground as Shen Jiu and Shen Yuan collectively humiliated the disciples entire bloodline, made him wish he was never born, and gotten the boy to completely withdrawal from being a cultivator or anything else of any importance ever again because he was clearly too incompetent for anything where he had to look over himself.
The sect leader, watching from afar to report back to Shen Jiu’s Shizun, nods in approval. He’ll have to invite this Shen Yuan boy to Cang Qiong if his speech is any good.
SY and SJ become bitch buddies. Then maybe more. But anyone who tries to question them ends up questioning their entire life choices, so it’s not a very popular topic. 
