A wealthy 19th-century Flemish landowner and businessman, Mr. Cogez rose from poverty through relentless effort to attain self-made affluence and nouveau riche status. He enforces rigid standards, particularly displaying dismissive attitudes toward the poor. Within his family, he exhibits controlling and abusive tendencies, especially toward his daughter Alois, forbidding her association with the impoverished boy Nello and igniting significant conflict. His volatile temper surfaces violently, like when a broken vase made him shake with anger, causing Alois to cower in fear; this behavior contributes to her stress-related illnesses. His wife challenges his strictness, advocating for their daughter and creating domestic tension.

A pivotal moment arrives when fire destroys his mill. Readily accepting false accusations blaming Nello for arson, fueled by the deceitful landlord Stephens, he bans Nello from contacting Alois and smashes a gift Nello gave her, reflecting his class prejudice and haste to condemn without evidence.

Later character development occurs: after Nello returns his lost wallet containing a substantial sum instead of keeping it, Mr. Cogez reconsiders. Learning the fire's truth from his servant Millie, he acknowledges his wrongful accusation. He then leads a blizzard search party for Nello and publicly kneels to beg forgiveness, demonstrating remorse and a shift from his former rigidity.

His surname appears inconsistently across adaptations: "Cogez" in the original novel, pronounced "Ko-zet-su" in the anime, and "Cogetz" in some dubs. Physically, he possesses brownish-tinted blonde hair, a trait inherited by his daughter.