begins with a lyric from the 1971 hit “Get It On ” by the glam-rock band T. Rex: “You've got the teeth of the hydra upon you / You're dirty, sweet, and you're my girl.” Their music opens and closes the film, harkening back to the Satanic Panic conspiracy that rock music featured subliminal messages—but it's the connotations of girlishness and impurity that crawl under your skin in that first moment, and throughout the film.
As Lee obsesses over the case, she also finds herself reflecting upon her childhood and her mother Ruth who she’s distanced herself from. She visits her, finding her seemingly in poor mental health and failing to take care of her home. Ruth, a devout Christian, asks Lee if she’s been doing her prayers to which Lee says she stopped doing them a long time ago, and that they always scared her when she was small.
As Lee is forced to kill her mother, it’s as if Satan’s grand scheme all along was to terrorize Lee from girlhood to womanhood so much that she needed to kill her mother; for his final act, he’ll show her just how pervasive evil can be. Staring at Ruby’s doll and unable to destroy it, it’s like she’s facing the trauma she’s suppressed her entire life.