The spine of the FBI is the rule of law. The spine of the FBI is a commitment to doing the right thing, in the right way, while protecting civil liberties.
Nothing scares me, because I used to think I was indestructible. Now I know I'm indestructible, not to mention my spine is indestructible. It's all titanium.
A spine to my films that's become more evident to me is that many are about the choices people make, and the reverberations of those choices. You go this way, or that way, and either way, there's going to be consequences.