4. Bruce Trusts Him With His Secret Identitiy
This is perhaps the most important element. Whilst Alfred obviously knew who Batman was, he served Bruce and tried to guide him. Lucius was always more of a risk. Why should he not just reveal who Bruce was to the world, especially as he makes him what he is in terms of equipment? Only six people ever knew that Bruce Wayne was Batman- Gordon only realised towards the end, Blake never knew him until the events of the final film, same with Selina Kyle, and Rachel didnt make it to the end. Fox is just as secretive as Alfred, because it is a burden he bears, and because he knows this he cares more for Bruce, knowing he is one of the few who can keep him truly safe. And an emotionally stunted man like Bruce trusts very few people, but Fox is one of these, but the films dont make as much importance of this as they do with, say, Alfred. An important moment that shows the amount of trust both men have in each other is when Fox agrees to help Batman locate the Joker using the sonar tracking network he is completely against. He threatens to resign, and means it, whilst that network is still in place. Batman respects him enough to do what he thinks is right and destroy it- and by typing in his name to deactivate it, he is the only man who can and probably would.