Andrew "Ender" Wiggen, is the protagonist and ultimately, the hero, of the novel. Set in the future, the story opens with the search for a child who can be trained into a perfect soldier for leading a battle against alien enemies known as "Buggers."
As a third-born child, Ender is already marked and different from his two older siblings and his peers. First of all, the government has banned families from having more than two children. Ender is only allowed to be born because his older brother and sister showed promise as potential leaders, but didn't quite pan out. All three of the Wiggen children are geniuses. The first, however, was too aggressive, too angry, and too much of a fighter. The second, also very smart, was too passive and too much of a peacemaker. Ender is a balance of both.
He is very smart and knows when to fight and when to hold back. He understands his enemy and does what needs to be done in order to win, but is also a very sensitive and empathetic character, who regrets hurting others, even in the name of survival. In school, he is picked on because he is a "Third." This causes Ender to be a loner from the very beginning. Because he has no friends, he learns very early how to be self-reliant and resourceful. When bullied by a group of older boys, he defends himself smartly and physically. He coaxes the leader of the group to fight him alone, and then he attacks quickly and completely, so he can prevent himself from getting picked on again. He knows this is the only way to end the fight, but at the end, he cries because he hates that he had to do it.
It is these initial qualities seen in Ender that make him the best choice as a future leader in the war against the Buggers.
I've watched through his eyes, I've listened through his ears, and I tell you he's the one. (Col. Graff, Chapter 1)