How we cite our quotes:
I have to win this now, and for all time, or I’ll fight it ever day and it will get worse and worse. (1.78)
This is Ender’s justification for wrecking Stilson – to send a message to all the bullies in school. (He has practically the same thought with Bonzo and his gang: “If I'm to walk away from here, I have to win quickly, and permanently” (12.92).) Although Ender doesn’t plan to kill these boys, he has a notion of winning “for all time” that seems more like war than, say, like a game. So we see pretty early on how war is a part of Ender’s life.
Ender knew the unspoken rules of manly warfare, even though he was only six. It was forbidden to strike the opponent who lay helpless on the ground; only an animal would do that. (1.79)
Here Ender comes out and says it: when he’s beating Stilson, he’s engaged in “warfare.” (Eh, haven’t we all felt that way about other people at school?) What’s also curious is that Ender realizes he’s acting in a way that will isolate him. By conducting war in this way, he’s making himself look like a monster or an animal. This leads him to question over and over whether or not he is a monster.
Ender felt sick. He had only meant to catch the boy’s arm. No. No, he had meant to hurt him. (4.66)
Here’s Ender fighting that internal battle with himself. Check out the argument he’s having with himself: I didn’t mean to hurt him… well, yes, I did. And we also see one of the effects of this war: Ender doesn’t like the dangerous, Peter-ish part of himself, so he feels sick when he acts that way. In other words, Ender has lost this little battle against that part of himself, and he’s his own casualty.