What are some important ideas in The Hunger Games?
The Hunger Games has several important themes or motifs that develop throughout the novel:
Trust-- Katniss struggles with trust from the very beginning. Having grown up in a situation where she had to depend on herself to provide for her family's survival, Katniss is used to counting on herself; for example, she hesitates trusting Peeta, because she doubts his motives for helping her.
Survival-- The Hunger Games themselves are a contest for survival of the fittest; Katniss must kill or be killed. Beyond the Games, Collins provides other examples of survival, especially in the first few chapters when Katniss reflects on surviving day to day in District Twelve and the 'Seam'.
Manipulation- Panem's control of the Districts through the media and The Hunger Games is a perfect example of how the Capitol manipulates their lesser citizens. The Capitol uses the Games as a reminder of their control and power.
Power-- The Hunger Games repeatedly hits upon the idea of power and control. From the Games themselves to the way that the Capitol suppresses the Districts in terms of poverty, work, harsh punishments, and pitiful allowances like tesserae, Panem uses fear and intimidation to maintain and strengthen their base of power. At the same time, Katniss works against the Capitol's base of power by defying the structure of the Games. She has no choice but to play along in the Arena, but she does so on her own terms, teaming up with Rue and daring to consume those poisonous berries in the final moments with Peeta.
I think it is also important to note that the Capitol seems to be allegorical to American society while the rest of Panem serves to show how the rest of the world survives around us. The Capitol citizens are overindulgent, obsessed with violence and pleasure. They do not see or care about the needs of those in more developing districts like district 11 or 12. Cinna represents moral hope for the Capitol citizens while Ellie epitomizes what the rest of the citizens are focused on and value.