I'm not entirely sure what portion of the novel you are inquiring about as Archie and Emile appear throughout the story. However, Archie and Emile represent the brains and the brawn, respectively, of the Vigils. Archie is the "assigner" of the Vigils, the individual responsible for creating the assignments which students are compelled to complete. Emile is the strong man who enforces Archie's will. When needed, Emile is there to carry out Archie's dirty work and use scare tactics to gain compliance. It is Emile who first accuses Jerry of being "queer" and it is Emile who Archie assigns to pair off with Jerry in the boxing match at the novel's climax.