In the arena, though, there was no place for kindness or compassion, and Jonathan and Martha feared what would happen to their son if he was forced to kill another tribute.
This is the essence of Superman - he would not use his powers to kill (movie aside
).
That was an excellent part of the "Hunger Games" books and movie - the powers that be were deliberately corrupting the youngsters. You had to kill to survive the arena. That was what made Katniss into a symbol of rebellion - when she elected to die herself rather than to kill.
