ok so i was Thinking....what is it that vein Wants as a character?—i think that by the end of yingdu chapter we get a vague sense of what could be the trajectory of xf's arc (resolving the mystery of vein's strange "death"), and in S2 we get lx's opaque "I wanna bring the parallel lines of time together" spiel...but vein?
in yingdu, he's at first characterised as a punisher or arbitrator of 'justice', (but that could of course just be lu guang projecting onto vein), and then later as not unkind but decidedly shady, transactional and with ulterior motives. and THEN, the hint of a past ("xiao weiying"); finally he's shown to be fallible, not really as terrifying as lu guang's nightmares at all.
we do not however, i don't think, get any sense of Why he's Doing All That, aside from knowing he's on allegiance with liu xiao, and does stuff solely for his own amusement.
which!!! led me to think about his origins, which we get a potential interpretation of via the story he gives to cxs when he goes into see wang qing. but outside of the canon, the PAIN mv lore (which i will not be quoting verbatim but might dig around to find it again), puts forward a slightly different version of that story. crucially, a fire caused by liu xiao is what gets vein what he wants— power and inheritance.
vein already got what he wanted. now, he wants nothing in particular; he starts a modelling agency on a whim, just because! sure, he'll go along with lx's plan, why not! he's at the top of the food chain now, he's is no longer the unlucky youngest son. but the missing piece that clicked in my mind is, he's also indebt to liu xiao.
so he's acting in part out of amusement and what he Thinks is his own volition, but it's tainted by this sense of debt that lurks beneath the surface. and to me this fact that vein is under the impression that he is in no way constrained by this debt, and the fact he may have been single mindedly preoccupied with power no matter the cost... gives me a feeling that at his core he might be kind of empty.
this also makes his fondness? fascination? amusement? with xia fei more interesting — someone who is young and scrappy and doesn't care what it takes to strive towards his goals; xia fei's "youthful defiance", and his determination. yet, xf is also full of this emptiness — he's not in modelling for pure love of the game, he just wants money, and his getting into modelling is framed as downright degrading ("body/shell for rent" and the scene where xf assumes his roommate is literally saying he should sell his body in That way). it's such a fun and fascinating contradiction, that both xf and vein bear.