Authors develop characters through such methods as description, dialogue, other characters' reactions and comments, and the characters' thoughts, feelings, and speeches and actions.
From what one reads, then, Lydia and George Hadley of Ray Bradbury's "The Veldt" are much like many contemporary parents: lenient, disconnected from their children, and ineffective and indecisive in their parenting. With nothing to do in their Happylife Home, the Hadleys have no chores for their children, and there is no need to engage in play with them because they have the nursery. Into this nursery, Wendy and Peter--ironically named for characters in Peter Pan--spend their time creating their own amusements. If there is anything to their relationship with their parents, it is antagonism.
For instance, when George and Lydia become concerned about what is occurring in the nursery after they are chased out by a virtual lion, George decides that he will shut off the house, telling his children. Then, Peter disrespectfully tells his father, "I don't think you'd better consider it any more, Father." Rebelliously, the children break back into the nursery after George closes it and tells them to stay out. After this incident, George talks with a psychologist since he cannot decide what to do on his own. Finally, when George does decide to shut off the house, the children "with wet faces" plead with him; to quiet them, George weakens and listens to his permissive wife who entreats him, "Oh, George,...it can't hurt [to turn on the nursery for a few minutes].
Wondering why they had ever bought the "nightmare" of the nursery, his wife replies, "Pride, money, foolishness." These characteristics have been their nemesis, as by allowing the children a few minutes, the nursery is changed to an African veldtland and the parents are attacked by beasts and killed. When the psychologist arrives, Wendy and Peter in their sociopathic unconcern at murdering their parents are polite and act civilized, offering David McClean a cup of tea.