((If I offend anyone, I'm sorry. Gif credits to respective owners)) This is one of the reactions that I started a long time ago and that I'm continuing now. I will be doing this in two parts. So please stay with me. Thank you!
Minseok: He sees you while he's on stage and hopes you stick around long enough to see him. When you do, he would just stare at you trying to pump himself up. "Wow s/he waited for me. S/he's right there...oh...Now s/he's looking at me. I should go say hi."
Luhan: He was very happy that you decided to show up to their concert again. Your face permanently etched into his mind. "Wow, s/he really is the most attractive person I've ever seen. " Be sure to stick around because this boy will be sure you know his feelings.
Yifan: He would bump into you before the concert, some how, and make plans to talk afterwards. The serious Kris you saw on stage would be completely gone and the dorky and awkward Yifan would be in his place. " Did you see how I danced? It was like this and...did you like it? I could feel your eyes on me while I danced."
Junmyeon: Knowing him, he'd want you to feel safe so he'd have a guard come and get you to see him. He'd run up to you and take selfies causing you try to figure out who the bigger fan here was. "You know...we should do this more often, don't you think?" He'd end up slipping you his number.
Yixing: His charm would be so overwhelming that you'd end up melting you right then and there. "Hey...I'm Yixing..I want you to call me, here. Be sure not to forget...because I sure won't forget about you. "Gives you a piece of paper with his number on it.
Baekhyun: He would probably get second hand nervousness from you, but he wouldn't want you to be nervous. He'd probably pinch your cheeks, trying to make you less nervous "Hey, no need to be so nervous, Beautiful.....I..I'm Baekhyun...you already know this...heh." You two would both be a bumbling mess.