Thomas - He forgets what he's saying and can't meet your eyes
Newt - He can't take his eyes off you, or get the smile off his face.
Minho - The usual level of sarcasm with just a hint of flirtation.
Gally - You made him speechless, which is a rare occurrence.
Alby - He is always smiling because being around you relaxes him.
Chuck - He isn't able to say anything other than 'hi' to you at the moment.