Kelsey, whose father died in a snowmobile accident, expresses her individuality through hair dye and piercings. Despite being called "trailer trash" by classmates, she becomes more assertive within the D Squad, standing by her friends.

An academically gifted fifth grader aspiring to be a lawyer, Judy is in the gifted program and often perceived as "snotty" by peers. She navigates social pressures while maintaining her high grades.

A child prodigy and chess enthusiast, Brenton creates a homework machine named Belch. Lacking a social group at school, he eventually forms connections with fellow D Squad members.

A new and enthusiastic teacher at Grand Canyon school, Miss Rasmussen emphasizes fun and group work in her classroom. She supports student individuality and is portrayed as kind and slightly naive.

A loner who suspects the D Squad of mischief, Ronnie attempts to uncover their secret activities. He is persistent and resents the group's achievements, particularly Snik and Brenton.

The police chief who narrates the introduction, Rebecca Fish is initially skeptical of the homework machine rumors. She is gruff but fair, eventually taking the D Squad seriously due to evidence they uncover.