Sucking actually produces endorphins, a natural-occurring chemical in our brain, which produces pleasure. Babies associate sucking with mommy, warmth, love, togetherness, nourishment and a myriad of other wonderful feelings. Children are born with a suckling reflex–-just stroke a baby’s chin and you see the instinctive response immediately. Shari, why do children suck their thumbs? I've never once connected with that as anything comforting or natural. I understand Bond joining her in the shower and all that (indeed a clever way of showing the two characters connecting), but the finger sucking thing just struck me as odd. Aside from the themes and character work there is Campbell's terrific decision to shoot in one take, Craig and Green's performance and David Arnold's beautiful score. It's one of the best and most complex scenes in the Bond series. The finger thing is his way of helping and there is a certain masculine vulnerability to the moment. You don't need dialogue, instead you have a simple elegant moment that is complex and interesting. He understands how she's feeling, because he's feeling that way too.

However, Bond decided to join her in the shower.

Whether you believed your own words or not. Maybe say a few words to inspire her not to be downcast by what she just witnessed. Perhaps throw a towel over her and dry her off. If you found a broken woman fully-dressed sitting in a cold shower, conventional logic would dictate that you would pull her out and warm her up. I found the moment to be reassuring and comforting. the whole Bond sucking Vesper's fingers scene how is that a comforting and soothing thing? I never understood it.

Casino royale vesper scene