In Ender's Game, the main character is called Andrew "Ender" Wiggin.
Ender has an older sister who is very compassionate and also an older brother who is rough and a bit aggressive. In a way, the main character got a little from both of them.
Andrew doesn't fight for no reason and he is generally speaking, a very nice boy, but when faced with a situation when he has to stand his ground, specially when it is about protecting someone he cares about, he will became an aggressive beast. When it comes to fight or flight situations, Andrew fights.
When confronted with a group of kids led by a bully, the character called Stilson, Andrew did not hesitate and even thought he was only six years old, he beat Stilson to death, although he wasn't aware of what he did when he did.
Ender is a pragmatic. He is a kid who is seen, mostly, as a victim who is being manipulated by adults but in fact, he understands the manipulation game more than many.
This can be seen when Graff is manipulating Ender. In fact, when that is happening, Ender is manipulating Bean while he is the commander of the Dragon Army.
