The Question and Answer section for Ender’s Game is a great resource to ask questions, find answers, and discuss the novel.
Peter was a sociopath and a "loose cannon". His behavior was too erratic and aggressive. Valentine was too socially conscious and kind.
This device had allowed the authorities to view the world as Ender did. From Ender's thoughts we learn that the monitor has made him an outcast. Ender has the monitor a year longer than Peter which makes Peter insanely jealous. Peter, however, is...
Ender's parents remain ambiguous to his leaving to battle school because Ender will have freedom from being a third and they will not be punished anymore. They are sad because they will miss their son.