A sharp-witted, seventy-three-year-old retired legal clerk whose life revolves around her meticulous daily ritual of writing letters. Fiercely independent but privately grappling with failing eyesight and deep-seated grief over the death of her son decades earlier, she uses correspondence to maintain control over her world.

Sybil’s kind and steadfast neighbor who lives next door and often tends to his garden. A widower and Holocaust survivor, he provides Sybil with practical support and quiet companionship as her vision deteriorates.

Sybil’s estranged daughter who works as an architect and lives abroad. Her relationship with her mother is strained by years of emotional distance and misunderstandings, though they attempt to bridge the gap through their letters.

Sybil’s dutiful but somewhat emotionally reserved son who attempts to care for his mother and manage her aging process, often to her annoyance. While he tries to help, he struggles to connect with her on a deeper, more vulnerable level.

Sybil’s loyal best friend and sister-in-law who serves as Sybil's primary confidante. She offers a sounding board for Sybil’s frustrations and memories and is one of the few people who knows the full history of the family's dynamics.

A troubled but brilliant teenager and the son of Sybil's former protégé. He strikes up a monthly correspondence with Sybil, finding in her a non-judgmental mentor who helps him navigate his mental health struggles and feelings of isolation.

A man who harbors deep resentment toward Sybil due to her role in his father's harsh legal sentencing years ago. He acts as a threatening figure, sending menacing letters and damaging her garden, forcing Sybil to confront her professional past.

Sybil’s ex-husband with whom she maintains a complex emotional connection despite their divorce. He remains a significant figure in her memories and internal monologue, particularly regarding their shared loss of their son.

Sybil and Daan’s deceased son who died in childhood; his memory haunts Sybil and shapes her entire emotional landscape. Although not alive during the present timeline, his absence is a central force driving Sybil’s character and her reticence to open up.

Sybil’s biological sister, a pragmatic botanist living in Scotland whom Sybil discovers late in life through DNA testing. She represents a new chapter for Sybil, offering a chance to explore her origins and form a family bond unburdened by the past.