My personal lwj headcanon:
lwj hates wwx at first – or at least tries to convince himself he does. He's so different, so utterly alien from everything he's ever known. lwj has lived by a strict set of rules his entire life-

-because they are just, because he should, because his uncle has always told him that's the way life should be and he has no other basis for comparison

Everything wwx does – his very being – flies in the face of that. And he doesn't care. wwx seems to do what he wants, whatever he wants, and never thinks about the consequences. A concept so strange to lwj that he understands nothing about him

wwx is at turns reckless, arrogant and dangerous. He is improper and breaks rules on an hourly basis – and lwj CANNOT stop thinking about him. It makes sense, he tells himself. wwx is such an oddity that of course his thoughts turn to him at every opportunity

But he stays focused, stays on the right path, because he cannot let the distraction that is wwx's very existance stop him from improving and learning all that he can. He is the Light Bearer, and he will rise above this

in the evenings, though, when his tasks are complete, he finds himself sitting at his guqin, plucking through a new piece that's started forming in his mind. He doesn't know the meaning of the song but it always feels full of longing, wanting, of a life that could be so different

It's not until they release the lanterns together and wwx makes his vow that he realises what it - all of it - means. That wwx's recklessness is bravery, his arrogance self-belief and that his seemingly dangerous ideas are simply the clever way he sees the world

wwx thinks differently to everyone he's ever known - but that's not bad, he begins to realise. It's just DIFFERENT.

That night, he finally gives the song a name.