The science fiction story has a family subplot built into it, concerning the siblings of Ender, brother Peter and sister Valentine.  While there are very few realistic details about their family life, it is stated early that both siblings have been tested and found wanting, Peter because of certain violent tendencies (made visible to the reader by Peter’s treatment of his brother and sister).  Once it is clear to the parents that they will have no contact with Ender (after two years), they decide to move from the city to the country setting of North Carolina as Valentine thinks, “among these threes, under this changeable and heavy sky”; she knows that Ender could never find them there, so it was a way of the parents’ admitting that Ender was “dead” to them, that they would never see him again.  They hoped that the pastoral setting might change Peter, “might have a softening influence on their strange and frightening son.”  But Valentine knows his new behavior is a fraud.  Throughout the novel, Ender fights against turning violent like his brother, and in his final act demonstrates that he is the opposite of his sadistic brother.