Bonzo Madrid (pronounced "bone-so", as stated by Petra Arkanian when Ender incorrectly pronounces the name as "bahn-zoe") is an antagonistic supporting character, serving to bring out Ender's brutal nature while at
Battle School.
Bonzo, whose real name is Bonito de Madrid, is described as a strikingly beautiful boy of aristocratic Spanish lineage from the town of
Cartagena. As commander of Salamander Army, the autocratic Bonzo suddenly has
Ender Wiggin thrust upon him when Ender is promoted from his launch group. Bonzo was forced to give up a veteran soldier (a toon leader) to make room for Ender, is further furious because Ender has virtually no experience in the Battle Room. Bonzo takes out these frustrations on Ender and as a supposed punishment, he forces Ender to do desk work when his army is practicing. He also prevents Ender from participating in battles until after 4 minutes have elapsed, and, even then, Ender is forbidden from firing his gun. This causes Ender's individual soldier ranking to be high, and Bonzo hopes that this will help him trade Ender to some other army.
Desperate to gain experience, Ender begins to practice with many "launchies," younger students at the Battle School who have not yet been assigned to an army. After Bonzo orders Ender to stop these practices, Ender antagonizes Bonzo by privately threatening to have Bonzo "iced" (kicked out of Battle School) if Bonzo does not rescind the order. Ender inadvertently makes the situation worse by explaining to Bonzo how Bonzo should rescind the order. Later, Ender disobeys Bonzo's standing order to not fire his weapon during battle, turning a defeat for Salamander army into a draw. Rather than being grateful that, by firing his gun, Ender helped the team, Bonzo hits him for disobeying orders to not fire his gun and transfers him to Rat Army. This backfires on Bonzo, however, and he loses the discipline he had with his army because they understood that Ender's "disobedience" had been beneficial.
Following a battle where Ender, now a commander, defeats Salamander Army, Bonzo is finally provoked beyond sanity. Ender, enraged at the Battle School teachers, accidentally humiliates Bonzo during the end of battle ceremony. Bonzo and a group of his cronies corner Ender in one of the Battle School showers. Ender manages to use Bonzo's honor against him and shame Bonzo into engaging him in one-on-one combat. Taking advantage of the slipperiness of his still-soapy skin, Ender evades Bonzo and quickly wins the battle. Bonzo is sent home to his family in a
bodybag, ironically on the same shuttle that transports Ender back to Earth on short leave. Ender does not know what happened to Bonzo, but he dreams about the fight when he is being trained in Command School. He vocalizes his fear that he thinks he killed Bonzo, and his realization is confirmed during
Hyrum Graff's court martial, where vids taken of the fight are used in an attempt to prove that Ender was abused by the Battle School staff.
The Bonzo incident is pivotal in Ender's development, as it forces him to realize that he must fend for himself at all times, as the teachers refuse to offer him help — an attitude fostered by Graff. Believing
isolation was the environment under which Ender would become the military genius needed for the Third Invasion, Graff attempts to put a psychological barrier between him and the other Battle School students at every opportunity. Despite this goal, he never intends to endanger the life of any student of the Battle School. By forcing Ender to take on Bonzo alone, without any adult intervention, Graff makes a mistake that stays with him through the rest of his career, one he continues to think of when making future decisions, and validating his own work.
While still at Battle School, Bonzo has an a couple of encounters with Bean. The first of which involved Bean playing along with Bonzo's pride and honor to learn about Ender Wiggin, and showed a possibly more friendly side of Bonzo. When asked about the continuous comparisons between Bean and Ender, Bonzo warmly replies that it only means he is younger yet expected to perform at their level; a pathetic joke to him. In his later encounter, where he and his friends attempt to intimidate him. Bean replies with insults, causing Bonzo to act out in anger. He pins Bean against the wall by his neck. Bean's reach is too short to defend himself and Bonzo strangles him almost to the point of fainting. Bean then believes he has fed Bonzo's anger and made things worse for Ender. He realizes how crazy Bonzo is and attempts to tell the teachers, who of course do not deal with the problem, allowing it to escalate.