Harold Darcy makes a single appearance in the novel, in Chapter 30. He's a student in Jerry's homeroom (with Brother Leon), and he's upset that Jerry isn't selling chocolates. This is after Archie and The Vigils make selling chocolate the thing to do at Trinity. When Darcy challenges Jerry in class, the other class members are right there with them. The Vigils have managed to turn almost everybody in school against Jerry, and things are about to get ugly for him.