
I like to imagine that from the very beginning, there was something inexplicable that drew Lan Zhan to Wei Ying (probably all the naughty, rule-breaking badboy antics that frustrated him to no end), of which Lan Zhan reasoned with himself it was that he wanted to discipline him. But soon after he couldn't stop thinking about him, and after they were forced to spend time together (a month?) everyday while Wei Ying was fulfilling his copy-the-rulebook-punishment, his love was cemented. gaHHH BE STILL MY BEATING HEART TT//////TT

I feel like maybe in the start, HGJ kinda felt envious (?) a bit of WWX. WWX is super easy going and always has fun and deep in his heart perhaps HGJ wanted to be like that too since his childhood he was always under microscope had to be a role model or something and so acted like he really hated WWX's flippant ways. Or maybe even himself he doesn't realise he was envious of him but found his gaze being attracted to WWX and with time he found himself knowing more about WWX. That there's more to him and fell in love? We shall never know (〜 ̄△ ̄)〜

I think he fell for WWX in first sight. Because in both of SVSSS and TGCF the seme fell in love with the uke in first sight. So I think this was same.
LWJ met WWX the first time at midnight when he was patroling around cloud reccesses. WWX's eye blinding smile is probably what made LWJ notice him. WWX carried two jug of emperor's smile with him. After a few words WWX started to drink the wine. It was probably a full moon that day. And WWX looked stunning as he was bathed with the moonlight. Drops of wine was leaking from the corner of his mouth dripping down all the way to his throat and then under his robes.
If you have seen the donghua you will be able to imagine the scene.
I just want to know that when wanji realise that he fall for wei ying. I can't figure it myself