I've written in these posts that your brain changes to accommodate what you do. I'm a college professor but still, my brain is close enough to junior high kids. I seem to remember that time very well. Junior high aside, I also couldn't put down the book.
So not to make this lecture too long, what makes Katniss so cool? I think that one answer lies in the fact that she functions outside of herself. From the moment Katniss volunteers in place of her sister until the end of the book, Katniss, highly self-aware, is nevertheless almost always on the outside looking in.
I remember one of our yoga teachers used to talk about that. "Float out of yourself and look at the person with all those plans, anxieties, pressures, feelings, deadlines, goals, strivings (yourself) with amusement."
For me, handbuilding clay sculpture is very much this kind of an experience. Feeling, molding, struggling, pushing, pulling, grabbing, gouging. All of it happens fast and furious and very much led by the unconscious.
Wish I could be as cool as Katniss.