Auguste Beau is Gilbert Cocteau's legal uncle, later revealed as his biological father. Adopted into the Cocteau family during his youth, he endured sexual abuse by an elder stepbrother. This trauma established an abuse cycle he later perpetuated against Gilbert from early childhood.

Auguste subjected Gilbert to sustained physical, emotional, and sexual manipulation. Initially aiming to shape Gilbert into an "obedient pet," his methods evolved to cultivate Gilbert as a "pure" and "artistic" individual through psychological control and exploitation of Gilbert's obsessive attachment. Auguste maintained significant influence over Gilbert, who remained emotionally dependent despite the abuse.

As a respected figure in French high society, Auguste leveraged his status to manipulate Gilbert's environment. Learning of Gilbert's developing relationship with Serge Battour at Lacombrade Academy, Auguste actively worked to separate them. His interventions contributed to escalating conflicts that led Gilbert and Serge to flee the academy.

Auguste embodies abuse's cyclical nature, his own victimization directly informing his perpetration of similar trauma onto Gilbert. His actions function as the primary catalyst for Gilbert's psychological fragmentation, promiscuity, and eventual downward spiral into self-destructive behaviors. The narrative frames Auguste as the architect of Gilbert's tragic trajectory, his manipulation persisting even after Gilbert learns their true biological relationship.