The Rainha-Mãe dos Mares, grandmother to protagonist Marina, commands the undersea kingdom as its unwavering matriarch. A guardian of tradition, she governs royal affairs with an emphasis on duty, presiding over her granddaughters’ rites of passage. She deliberately withholds Marina’s pearl hairpin—a sacred emblem of adulthood—until the young mermaid proves readiness to embrace her role. During pivotal teachings, the Queen Mother delineates the divide between merfolk and humans: mermaids endure three centuries before dissolving into sea foam, bereft of souls, while humans inherit eternal afterlives. This revelation fuels Marina’s longing to gain a soul through love. When Marina rescues a prince, the Queen Mother recognizes her granddaughter’s resolve, bestowing the hairpin as both reward and challenge. Her authority anchors the kingdom’s order. She rebukes Marina’s impulsiveness, stressing the dangers of defying merfolk laws, and her doctrines linger in Marina’s choices even as the queen steps from the narrative’s forefront. Bound strictly to her role as a custodian of heritage, her history remains rooted in wisdom and lineage, her influence echoing through royal decisions without elaboration on her past or future beyond the core tale.