Ender's Game Chapter 2: Peter
We meet Valentine and Peter in this chapter, Ender's siblings after Ender gets home from school. While all three children are obviously brilliant, they have extremely different personalities. Peter (the eldest) is brutal, angry, and remorseless. Valentine, the second, is sweet, compassionate, and hopeful. Ender, the youngest, feels himself torn as he is as brutal as Peter, but as compassionate as Valentine. This chapter explores their relationship. All three children had been "Monitored" at one time, and losing it was a rite-of-passage: the government does not consider the child worthy of becoming an officer in Earth's army to defend against the Buggers. Peter feels vindicated that no sibling is superior to him, and, predictably, bullies Ender. " 'I could kill you like this,' Peter whispered. 'Just press and press until you're dead.'" Chapter 2, pg 12
Valentine feels compassion for Ender. With Peter's bullying of Ender, she, predictably, defends the youngest against Peter's nearly fatal attack. " 'And do you know why you don't mean it?' Valentine asked. 'Because you want to be in the government someday. you want to be elected. And they won't elect you if your opponents can dig up the fact that your brother and sister died in suspicious accidents... 'You're his monitor now,' said Peter. 'You better watch him day and night.'" Chapter 2, pg 13
At the end of the chapter, Ender lay awake, awaiting Peter's final attack. When Peter approaches, Peter apologizes over the apparently-sleeping Ender, surprising Ender.