Unless any of these stills actually contribute to the plot of Stay With Me, then it's probably more likely that whoever's in charge decided to forget the script and just put its two leads in fun outfits that make them look sexy as hell.
Wang Kai is seductively hot as a vampire and equally alluring as a gallant wuxia hero while Joe Chen hops from a playful bunny to Dongfang Bubai, a formidable martial artist that is hailed the Invincible East. Joe Chen is not merely cosplaying because she literally played Dongfang Bubai in the 2013 adaptation of Swordsman. She owned that role if you ask me and she also owns this shoot.
I wasn't sure whether or not I'd have time to watch Stay With Me but the endless barrage of stills certainly make it hard to resist.