Lucas- On the inside he'd be shocked and pleasantly surprised but you wouldn't know from the outside. He'd smirk at you and wiggle his eyebrows, probably trying to come off as sexy, but it'd more likely be goofy and cringey.
Jungwoo-He'd be so blushy and shy and wouldn't be able to be make contact but would be so flattered. You'd still have to make the first move though
Taeyong-He would be shocked like Lucas, but unlike him, wouldn't be able to hide it, despite trying. He'd more confrontational, straight up asking if you were staring, in which his voice might break just a little bit
WinWin-Wpuld smile at you and feel so flattered, make a mental note to show it off more whenever you're around him, and even sit on your lap
Jaehyun: would either smile at you and wave as if you'd be staring at him in general, but he knows it was his ass. Later he would confront you, coming behind you, Liao to your ear, and say something cheesy that wouldn't come across as cheesy, like, "glad you enjoyed the view." He'd possibly add a 'baby boy' to that, or princess if you're into feminisation
Doyoung: would act like he hadn't noticed, but deep down it would confirm that you had feelings for him, and he'd be pleased with that. Hed later but you a drink and ask you how you felt
Ten-Would laugh about it, giving no indication that he liked you on that way at all. But from how much he bent over the rest of the day, he made it clear that he lived to tease you
Mark-Would be a little uncomfortable at first, conscious that something was wrong with it. You'd have to compliment him on it, or even reach out and grab it before he got the message.
Taeil-Would look down and be blushy, but doubt that you're actually interested in him. Like Mark, you'd have to put your hands on him before he understood your intentions. Whether that was sex or a relationship.
