Carrie may or may not be in love with Nick Brody, and may or may not be aware of it. Nick Brody killed the Vice President in part to save her from Abu Nazir, her mortal enemy, whom she has since vanquished. (She's the only one that knows about that part, and it's causing her a bit of an itch.) Walden's accomplice in black ops, David Estes, has ordered Peter Quinn to assassinate Brody, now that he's helped them get Nazir. (Saul's the only one that knows about that part, and it's causing him to get railroaded by Estes.)
But previous to that, Carrie Mathison was a person who thought life was a bicycle, that if you stopped moving you'd fall right off. For our first year with her, she leaned a little too far left and fell over. This year, she's leaned a little right. But her forward vector never stopped. Sometimes this desire to put the world between us and ourselves, the inability to be alone with silence, takes the form of heroism.
Every martyr is first and foremost a terrorist. A dissident on hunger strike is just another kind of hunger artist. And like any terrorist, the martyr is gifted with an illness that says what we symbolize is more important than who we are. That humility's best expression is in self-abnegation: A beautiful thing, but not the most beautiful possible thing. To make up for letting 9/11 happen, she set up a system by which this natural tendency -- to go and go, to never stop, ever fall over -- could masquerade as heroism. And like the martyr, the end result was a good thing. Lives saved.
I think regardless of what it is Carrie dedicates her life to, it's still a pretty bad thing to do so. We are a lot larger than we can really comprehend; we have it in us to contain not just multitudes but fundamental opposites. This entire show is crammed full with people who have -- you can't name more than three who haven't -- shaved off the contradictory parts of themselves and become razors, one thing only, always moving forward. Sharks, in the quiet. It is a very beautiful thing but it is not a very healthy thing.
"You gave it up to me," Nick will say. "Completely." And she'll know he's right. But before that, Saul will say, "You're throwing your life away," and she'll say no: She's just not giving it away. Saul is one thing only, and his love for Carrie comes out of the idea that they are the same. And he's right. But because she's giving up herself to something he can't, it looks like they are not the same. It looks ugly to him. He fights it like an addict fights recovery, striking blindly at her softest places because can't stand the change in vector: Her madness is only acceptable as long as it's useful; her self-abnegation is only positive so long as he can understand it.