Abby Rivers is the protagonist of My Best Friend’s Exorcism. She is 16 years old during most of the novel. Abby is driven and loyal, qualities which help her rescue her best friend, Gretchen Lang, from demonic possession. This is no easy task because most people don’t believe her concerns about Gretchen or ignore them. She doubts herself at times, obsessing over her parents’ change in socioeconomic status and hiding her acne, but focuses on helping her friend. By calling upon their friendship and shared interests, Abby succeeds in exorcizing the demon Andras from Gretchen. All of this develops The Complexity of Friendship: Abby and Gretchen experience bad and good times, but their friendship is paramount for their survival.

Abby’s struggle with isolation also develops The Challenges of Adolescence. The adults of Charleston, South Carolina, are framed as ignoring problems, finding this approach more comfortable. When people treat Gretchen’s possession this way, Abby resists as she knows Gretchen is suffering. However, her resistance is met with isolation. Her youth puts her in contention with adults like her parents, educators, and even Christian Lemon (Brother Lemon), the exorcist who helps her—pushing her to acknowledge Gretchen’s possession and believe it can be fixed.