Cap: he wouldn't notice at first, too caught up in being silly, until he sees you trying to cover your face. He would cock his head and smile. "What are you doing jagi?" He would peel your hands away and eye smile cutely, making you blush harder. "Why are you hiding this from me? It's cute kekeke."
Ricky: he would be doing aegyo, trying to make you smile after a bad day. As soon as he saw the slightest smile and blush on our face he would freak out. "Ooooooohh! Ohohoh! I did it! You smiled!" If you tried to cover your face he would just pull your hands away and pout. "Jagi, I just want you to be happy."
Chunji: he would drop his jaw, and kid of stare at you for a minute. You would blush even harder, as eventually turn away, making him snap out of his gaze and grab your shoulders to turn you around. "Nonono! It was cute! Ok, I reacted bad.. but you really do look cute. Can I see?" You would turn around and a faint blush would appear on him. "Too cute!!!!" He would squeal and take your hands in his, twirling them around so you couldn't cover your face with them.
Changjo: he wouldn't even be doing aegyo, just talking to you, and as soon as he brings up how good you looked today-BAM. Bright red. You wouldn't try to bring attention to it, hoping if you don't do anything he won't either. Too bad so sad. He would continue talking, until he saw how hard you were trying to look like you didn't know, and then he would cock his head a little and trail off his speech. "You ok there?" He would laugh cutely and a little awkwardly, but you just nod and motion for him to continue on with his story.
Niel: I see two scenarios for this. One where he's doing aegyo, trying to make you smile. His reaction would be a little like chunjis, but he would celebrate more on the fact he got you to blush than stand there and stare. "Am I really cute?" When you nod he would almost attack you with a hug. "I knew it. Not as cute as you though." The other way, would be you two just talking and joking around. he would smile, laughing a little, but try to continue on what he was saying. He would fail, and start stumbling, causing him to be embarassed and start blushing himself. "Ah.. Jagi.. Now I'm pink."
L.Joe: he would look down, blushing himself. "Ah, I'm sorry. Was it something I did?" He would look up at you with a soft smile, and you would slowly nod. he would chuckle a little, then cover his head with his hands and hang it again. "Aish. I can't believe I did that." He would pause for a second before looking up a little. "I can't believe you did this...so much for being manly." Gesturing to himself.