I completely agree kygal & joyce. In a way they are both "outsiders" looking in. Jacob not an actual FBI agent, and Aurelio not a corrupt game player. They both have their own way of doing things in a kind of quiet, determined, no fuss fashion. Both a bit reserved, both thinkers.
It's nice to see Aurelio be allowed to expand the quick witted humour that we saw glimpses of in Jacob but which i think Rufus was never allowed to show as much as he would have liked to. He always wanted EH to be funnier than it was and there was certainly the scope to inject more humour as a counterpoint to some of the dreadful cases that Jacob and Rachel had to deal with. One of my favourite scenes will always be in the airplane with the exploding ginger beer bottle, and the air hostess saying "they were in the galley, you know....." and jacob replying "what? making sandwiches?" in response to her hand gestures, leading on to the "don't knock it til you've tried it" comment to Rachel about the mile high club. It was a fantastic, funny scene and really showcased the naturalistic, quick witted, dry banter between them.
Oh and here's a nice picture of Aurelio Zen, he's a bit of a snappier dresser than our Jacob (being Italian of course), but still bites his bottom lip and has his hands in his pockets!!