The primary antagonist in Opaline's storyline, Lyndon is initially believed to be Opaline’s much-older brother. He is controlling and attempts to arrange Opaline’s marriage. His cruel and self-centered nature surfaces through his need to command obedience and control.

Opaline’s complex and self-serving lover from Morocco who lives in Paris. He works as a rare book dealer and becomes increasingly misogynistic and vindictive when Opaline refuses to give him control over the Brontë manuscript.

An Austrian prisoner of war during World War II, Josef is kind and contributes positively to Opaline’s life. Their relationship deepens after he returns to Dublin years later, offering her a chance at lasting love.

An eccentric figure for whom Martha works after leaving her abusive husband. Madame Bowden owns the house next to the mysterious bookshop that features in the elements of magical realism within the story.

Martha’s abusive, estranged husband and antagonist in her storyline. His jealousy and control result in a tumultuous relationship, eventually leading to his death under mysterious circumstances related to the novel's plot.