No romance de fontes , várias razões foram dadas para a escolha de Ender e seus tenentes em tão tenra idade;
- Apenas Ender, como Comandante, tem suficiente empatia para entender os padrões de voo altamente complexos usados pelos Buggers (os Formics) mas suficiente agressão bruta para combatê-los em seus termos próprios. Note que eles ainda tinham que enganá-lo. Se ele soubesse que estava enviando homens de verdade para a morte, ele teria recusado.
We had to have a commander with so much empathy that he would think like the buggers, understand them and anticipate them. So much compassion that he could win the love of his underlings and work with them like a perfect machine, as perfect as the buggers. But somebody with that much compassion could never be the killer we needed. Could never go into battle willing to win at all costs. If you knew, you couldn't do it. If you were the kind of person who would do it even if you knew, you could never have understood the buggers well enough."
- Somente as crianças têm a necessária coordenação motora necessária para pilotar e controlar as frotas de massa.
"And it had to be a child, Ender," said Mazer. "You were faster than me. Better than me. I was too old and cautious. Any decent person who knows what warfare is can never go into battle with a whole heart. But you didn't know. We made sure you didn't know. You were reckless and brilliant and young. It's what you were born for."
- Eles criam e selecionam crianças para a grandeza marcial por 50 anos. Ender pode ser jovem, mas ele é descrito (com toda a seriedade) como sendo literalmente uma das maiores mentes militares de todos os tempos, independentemente de sua idade
Por que eles não escolheram Mazer ou Graff para liderar a Frota (acima e além das razões acima) é que Graff é um general que nunca lutou uma única batalha espacial e Mazer é considerado um excêntrico cujo pequeno "golpe" força "marcou um insanamente sorte golpe de última hora contra a frota Bugger. Ele nunca foi totalmente confiado pela administração porque nunca foi capaz de explicar aos responsáveis exatamente o que aconteceu. É só quando Ender chega que ele finalmente encontra uma mente que está em pé de igualdade com a sua:"Does it ever seem to you that these boys aren't children? I look at what they do, the way they talk, and they don't seem like little kids." "They're the most brilliant children in the world, each in his own way." "But shouldn't they still act like children? They aren't normal. They act like history. Napoleon and Wellington. Caesar and Brutus."
"The videos of the Second Invasion, when they were destroying our fleets out in the comet shell." He began to call them up and display the buggers' patterns. "Show me the queen's ship." It was subtle. Ender couldn't see it for a long time. The bugger ships kept moving, all of them. There was no obvious flagship, no apparent nerve center. But gradually, as Mazer played the videos over and over again, Ender began to see the way that all the movements focused on, radiated from a center point. The center point shifted, but it was obvious, after he looked long enough, that the eyes of the fleet, the I of the fleet, the perspective from which all decisions were being made, was one particular ship. He pointed it out. "You see it. I see it. That makes two people out of all of those who have seen this video.
No filme eles encobrem isso, simplesmente observando (na introdução )
The International Fleet decided that the world's smartest children are the planet's best hope. Raised on war games, their decisions are intuitive, decisive, fearless. I am one of those recruits.