First appears in: The Prime Trees
Persephone is the local star of the Valaraldan solar system, acting as the sun that illuminates the ancient elven homeworld. A night watchman named Haemir casually refers to it as "Old Persey," noting that it is typically "bright and strong, as usual". The system originally contained six planets, with Valaralda orbiting "fourth in line".
As the ancient Fennas Elenathon gate device activates throughout the series, the Persephone system undergoes massive, impossible changes. First, Earth (Mar) is teleported across the universe, appearing as a new planet "orbiting just slightly inward from Valaralda, closer to the star". Later, the system is disrupted again when the planet Eryn suddenly arrives, completing the gathering of the three Prime Planets necessary to unlock the Defense Mechanism before Guruthos reaches them.