Ender was invented as an 8 year old who thought he was playing war games at his school. He was scary, yes, because he was willing to kill when he felt it needed doing, but originally, at least, he was conceived as not realizing just how his use of the war games was going to be used.

A lot of people are willing to hate the movie, however, just because Ender was conceived and originally written by Orson Scott Card, whom they execrate because of his positions on gays. He's a devout Mormon, how did they think he was going to feel about gays?
Regerds, Pete