Themis reigns as goddess of fire and ruler of the Fire Kingdom. She ignited the creation of the Holy Flame at the ocean's edge to pacify the seas and grant eternal life to her fire descendants. This pivotal act followed a historic conflict where Argon, Lord of the Winds, deceived both Themis and Glaucus, the sea god, sowing discord that erupted into a devastating elemental war. Intervention by the highest god resulted in Argon's imprisonment and the permanent separation of the fire and water realms.

Enforcing absolute prohibitions against contact between fire and water beings, Themis designates her daughter Malta heir to the Fire Kingdom, charging her with guarding the Holy Flame until her sixteenth birthday. Discovering Malta's secret romance with Sirius, prince of the Sea Kingdom, Themis condemns this betrayal. She imprisons Malta and confronts Glaucus to reinforce their ancient enmity.

When Malta allows the Holy Flame to extinguish during a meeting with Sirius, Themis mobilizes her forces to retrieve her daughter. She swiftly recognizes Piale's sacrifice in becoming the new Holy Flame, revealing her perceptiveness despite initial deception. Themis's unyielding hostility directly fuels the lovers' tragic fate: Malta ascends as Fire Queen during the eclipse, while Sirius perishes in sunlight seeking her. Witnessing their deaths and learning of their plan to reach the unity star, Themis expresses profound regret alongside Glaucus, acknowledging their own roles in sustaining the divide.