Not only are these three characters siblings, but they all three have been monitored by the military government, to determine their suitability for the intense training program leading to the anticipated conflict with the Buggers. Their differences, however, are what moves the novel away from a simple science fiction work toward a novel about growing up. While they were all very intelligent (and not even teens yet), their basic underlying personalties were quite different. Peter has a mean and violent personality, actually torturing and taunting his brother Ender and his sister Valentine. Valentine is loving and supportive of Ender, and sees through Peter's anger; Ender, on the other hand, is afraid he may have the same mean streak--in his encounter with the bully before entering the training program, in which he uses more force than necessary (he justifies it by saying he wanted to intimidate the bully's friends). His potential violent streak comes up again during his training when another bully tries to gang up on Ender. In the end, he is the most anti-violent of all.