During the reign of Queen Weira ( Elyon and Phobos' mother ) Cybele was one of the royal maids working in the palace, and more importantly, she was also the maid in charge of raising and taking care of prince Phobos. 

 According to the laws of the land, it was the duty of the Light of Meridian to produce another Queen and not concern herself with sons. The newborn prince would be handed to a servant like all of the other male heirs, and grow up to be a gentleman of the court and eventually be married off to a noblewoman at the highest bidding or for some land alliance. 

 Being very motherly in nature, but unable to have children of her own, Cybele loved Phobos as her own son from the moment he was placed into her arms, and continues to love him unconditionally.