Aroa, alternately called Alois Cogez or Cozets across adaptations, hails from a wealthy 19th-century Flemish family near Antwerp. Her father, Baas Cogez, a prosperous landowner who built his fortune through labor, enforces strict social boundaries and vehemently opposes her friendship with the poor orphan Nello. Despite her privilege, Aroa treats everyone warmly, forming a deep bond with Nello and valuing his artistic talent, frequently requesting his drawings. Her mother, Ellina, shows more understanding of Aroa's feelings yet wields little power over Baas Cogez's edicts.

Baas Cogez explicitly forbids Aroa's friendship with Nello. This prohibition intensifies when Nello is falsely accused of arson, prompting her father to enforce their separation more harshly. During a grave illness, profound emotional distress overwhelms Aroa, worsened by her isolation from Nello. Though initially refusing his visit, a drawing he creates for her – depicting shared memories of their village and windmills – brings her solace and aids her recovery, underscoring their connection's depth. Later, against her wishes, her father sends her to boarding school, severing her further from Nello and the village. His authoritarian behavior also contributes to her delicate health.

In the 1997 film adaptation, Aroa's story extends beyond the main narrative, showing her as an adult nun reflecting on Nello's life and their childhood, framing the tale through her recollections and adding retrospective depth.

Throughout adaptations, Aroa remains defined by her kindness and loyalty, consistently advocating for Nello's acceptance in their community. She undergoes minimal personal change, instead serving as a steadfast emotional anchor for Nello amid his struggles. Her story concludes with her mourning his tragic fate, highlighting the unresolved social divisions that shaped their lives.