Sarah Frances Russell, Lynn’s elder half-sister, is the daughter of George Russell and his first wife Frances, who passed away soon after Sarah’s birth. Harboring unresolved grief and a sense of abandonment, Sarah initially maintains a cold distance from Lynn, her guarded nature shaped by chronic illness and years of isolation. Their shared experience of maternal loss and familial fractures gradually forge a resilient bond, softening Sarah’s reluctance to connect.

Her evolution from emotional detachment to protective mentorship defines her arc. Early jealousy and resentment give way to fierce loyalty, compelling her to confront adversaries like Thomas and Mary Waverley and challenge authority figures—including her grandfather—to secure Lynn’s rightful place in the family.

A gifted flutist and painter, Sarah channels her introspective struggles into music, echoing her late mother’s artistic legacy. Her childhood friendship with Arthur Brighton blossoms into a devoted marriage, contrasting Lynn’s turbulent relationship with Edward and underscoring Sarah’s role as an emotional anchor.

After losing Marble Mansion, Sarah resides at Woburn Castle with her grandfather while Lynn relocates to Montgomery Mansion. Despite physical separation, the sisters unite in their resolve to reclaim their home and mend family divisions, exemplified by Sarah’s efforts to reconcile her grandfather with Lynn’s mixed heritage.

Internal conflicts plague Sarah: fears of inadequacy clash with her pursuit of her mother’s idealized "true lady" persona. Her journey weaves resilience with reconciliation as she navigates societal pressures and personal trials. Adaptations nuance her portrayal—the anime amplifies her compassion and agency, while the manga initially depicts her with sharper edges.