The Fravashi — a pre-existing, pure divine spirit or higher self. According to later texts, the Fravashis voluntarily descend from the divine realm into the material world to help Ahura Mazda fight against evil (Angra Mainyu) and advance the cosmic struggle. They act as protectors and guides during life. After death, the soul reunites with its Fravashi on the fourth day, bringing back the fruits of its earthly battle.
A motif of a divine being choosing to leave its heavenly station, enter the world of conflict and forgetfulness, fight the good fight, and ultimately return to contribute to the final victory.
On the royal side, Ahura Mazda is the supreme King of Wisdom, and the final goal is Frashokereti — the complete renovation of the world where evil is defeated and divine order (best dominion) is fully restored. There's also the Saoshyant, a future savior figure born of royal/divine lineage who will lead the final battle, resurrect the dead, and establish the perfected kingdom.