I did promise an explanation one last time on the Courtship Rite. I did go in depth on the ceremony back "War of Change" after S2 completed. So this explanation won't be as long. But in short some things remain the same as with the Adepti and yokai but there's very key differences Zhongli mentions but Baizhu hinted at and Xiao experienced.
The first difference is due to yakshas all having predatory illuminated beast true forms such as Xiao's Vermillion Bird form, their instincts are extremely strong and can even be aggressive. The adepti and yokai think no yaksha has ever preformed this rite...this is in fact false. It has happened but it was never with mortals and only ever in secret within their tribes. They are extremely sacred to them as unlike some races yakshas only ever take one mate and it's always their soul mate. The yakshas call it something completely different in fact: Soul Bond.
Soul Bonds go far beyond the 3 steps of Courtship Rite and will most assuredly trigger a great deal of agony for the one who triggers the ceremony. They are very often confused for the same thing. Like the yokai and adepti it starts with the 3 stages from Courtship Rite and uses pretty much the same ritual. But that's where the similarities end. Unlike the adepti and yokai and other elementals, the mate's mark of the intended begins to fade after they have the third step completed. This begins to trigger what yokai and adepti mistake for a rebound which can be extremely painful. Xiao was too young unfortunately to know this, having been a slave for a long time before Zhongli rescued him. And his tribe died out before he could learn properly. Otherwise the other yakshas would have taught him Yaksha Health Class 101. lol
Baizhu however knew instructing Lumine to do what she did. The Soul Bond phase causes a great deal of agony as I mentioned, it feels like your body got dunked in magma that's the best way I can describe it(ouch...that'll hurt). Their instincts get extremely strong and they become far too dangerous to approach safely once their eyes, markings, and hair change color. This is why everyone and Paimon were instructed to stay away. There's only two things their primal side desires once in this state or it begins to take hold.
The desire to mate and destroy anything that they see as a threat to that mate before the Soul Mark is placed, their souls "bound together" and mating completed. The mark acts as a bounding of souls, making it easer to track where they are between both mates, letting them know if they are near or far away(not exact location its like a game of hot'n cold). The ability to be empathic to each other's emotions remains the same like with the adepti and yokai. The soul bond is something not common knowledge outside the yakshas so how did Baizhu learn it? Who dare say how he learned it? Only time will tell. But the fact remains while Xiao didn't know much on the Soul Bond due to his age his instincts did and were what guided him. I should mention if the intended at any time turns out to be in "heat/rut" this ups the aggression to threats and the yaksha in question grows anxious and restless. Which is very apparent during late spring and autumn every couple 50 to 100 years. Hopefully this explain things and cleared some questions.
Also if you desire to use this idea for stories, I don't mind at all! Actually I'd be very curious how you use it if anybody does use it. :D That's all for this lil piece from my files. I'll see you guys this summer and this concludes S3 officially and completely.