Jerry Renault plays on the freshman football team at Trinity High School. He desperately wants to make something of himself, to "do something, be somebody." Early in the semester, he takes a stand against the school's authorities—both official and unofficial—by refusing to participate in the annual chocolate sale. At first, this move makes Jerry something of a hero to his fellow students, but he continues to feel inwardly conflicted and isolated throughout the novel. Eventually, the tide turns, and the other Trinity boys begin to despise Jerry for holding out against the sale. Viciously bullied, he discovers "doing your own thing" sometimes comes at a heavy price.
Archie Costello is a Trinity upperclassman who runs the secret society known as The Vigils. He is nominally the group's "assigner," the one responsible for dreaming up pranks and stunts and ordering other students to carry them out. Although Carter gets to issue orders and bang the gavel as president, Archie is the group's real, unofficial leader. Archie has made enemies of many boys at Trinity, but most are too timid to overtly challenge him. Even his fellow Vigils Obie and Carter are usually willing to let Archie have his way despite their mutual grudges against him. Key to Archie's survival is his ability to psychologically size people up, picking on those who will not—or cannot—take revenge.
Brother Leon is nominally the assistant headmaster of Trinity High School, but with the actual headmaster hospitalized for a serious illness, Leon is the school's de facto leader. He is fully aware of the existence of The Vigils but makes no attempt to suppress them. Instead, he hopes to use their power over the other students to guarantee the success of the chocolate sale. This year, Leon has overextended the school's finances to purchase a huge amount of chocolate, which he hopes to sell at double the usual price. If the sale fails, Leon will be in serious trouble with the other members of his order. If he succeeds, on the other hand, Leon stands to become the school's permanent headmaster.
Roland Goubert—known to the other boys as "The Goober"—is a Trinity freshman and Jerry Renault's best friend. A born runner, he makes the freshman football team but quits when he feels he is abetting the "evil" pervading the school. The Goober cannot stand confrontation and becomes anxious as the conflict between Jerry and Brother Leon heats up. He pleads with Jerry to stop boycotting the chocolate sale, but to no avail. Intimidated by the other boys, he offers only weak gestures of support as Jerry becomes a victim of bullying.
Obie, a senior at Trinity High, is the secretary of The Vigils. The job sounds important but ultimately comes down to keeping Archie happy and having to "buy him Hersheys all the time to satisfy his craving for chocolate." This clearly hierarchical relationship bothers Obie, who nurses a not-so-secret wish to see Archie get his just deserts. Obie seems to be of two minds concerning his role as Vigils secretary. On the one hand, he thinks the Vigils are "cool" and likes the prestige of being an officer. On the other hand, he recognizes being a Vigil has kept him from achieving other life goals, such as trying out for the football team.
John Carter, The Vigils' president, is a talented boxer and football player who respects fair play and honest effort. He initially respects Jerry as a fellow athlete. Anxious to see himself as one of the "good guys," Carter hates the feelings of guilt Archie stirs up within him. Carter's conflict with Archie is more fundamental than Obie's. Brawny but not brainy, Carter disapproves of Archie's psychological game-playing and wants to use violence to reestablish the Vigils' supremacy. He seems to see contests of physical strength as purer and more honorable than battles of wits.
Emile Janza is a school bully who gets his way not through physical violence, but by intimidating and embarrassing his victims. He gets drawn into the "chocolate war" partly because it gives him an excuse to torment Jerry Renault. An important thread of the novel's plot concerns Janza's relationship to Archie. Janza looks up to Archie and admires his knack for deceit and manipulation. He wants to become a Vigil and, in general, to be more like Archie. The feeling of respect is not mutual: Archie sees Janza as a contemptible "animal," not a kindred spirit.