The 爱情 三角形, 三角 inbetween Katniss, Peeta, and Gale, and the different weapons used. Some are sort of primative, like the spear, but then there are all the pods guarding the capitol, Katniss' special bow and 3-power arrows, and the Holo.
The whole anti-utopian theme of it all. I 爱情 how tough Katniss has to be and how 你 really come to know her throughout the series because of everything she has to go through.