Some 40 years prior to the events of W.I.T.C.H., Nerissa served as the leader of the Guardians of the Veil and as the Keeper of the Heart of Kandrakar. However, the Council of Kandrakar feared that the power of the Heart was corrupting her, and took it from her believing that doing so would save her from her newly discovered obsession for power. After Phobos' downfall, Nerissa became the primary antagonist and began to move against the Guardians. She freed some of Phobos' minions and set them against the Guardians. Also, she attempted to subvert and disrupt their daily lives on Earth.