There's defiantly a side of Jack that he doesn't show. We saw a little of it in DMC when he was in his cabin,trying to work out the compass and the map. He seemed annoyed and I think that,because we never really saw his cabin in CotBP,and we get quiet a few looks of it in DMC,that we will see his more personal side. Since his cabin seems like a personal place.
He just had work laying out. I'm sure if he went in there to meditate or start fantasizing about Lizzie, we would have seen it a lot cleaner. He's just busy with work. I'm sure he gets up every morning and whistles while he works. Maybe a few friendly seagulls come in and land on his shoulders whistling with him.