Oh, gosh, anon. I know I seem to pay a lot of attention to Colin and Katie, but unfortunately, not that much attention. ;) Although! I do remember screaming “DILATED PUPILS!” during the bondage scene in 4x06. HOWEVER. Scientifically speaking pupils do dilate when light conditions change, especially if it’s dark… so I’m not reading too much into them, to be honest. 

As for when they’re doing an interview… I’ve never seen a HD interview that has enough of a close-up of their faces to know if their pupils have dilated, so… ;)