Arianrhod originates from Welsh mythology and plays an important role in the fourth branch of Mabinogion. Her mother is Dôn and during the story of Mabinogion, she gives birth to two sons, thanks to magic. She would give birth to the first son named Dylan Ali Don after being told to step over a magician's rod in order to test her virginity. Embarrassed and shamed at the court while giving birth to a child in the process, she cursed her second son Lleu Llaw Gyffes with a wife, a name, and the right to arm himself with weapons.
Arianrhod is sent by the Angels to assassinate Jin at the beginning of Fire Book. She first informs him how the apocalyptic battle called Armageddon is about to begin and everyone must split between two factions, whose battle will bring about the end of the world. Her attempt to end his life is thwarted thanks to the timely arrival of his demon partner Rand, who along with several of Jin's demons arrive and kill the assassin. In Ice Book, Arianrhod can be recruited in Muspellheim by bringing her future self to meet her younger self. In gratitude, the future Arianrhod joins the party.
"A Welsh goddess of the moon also known as Arianfuroddo. Arian means "silver" and furoddo means "wheel". Her wheel was said to be used to ferry the dead to the afterlife. The moon symbolizes death and regeneration, which is why she is also highly worshiped as the goddess of rebirth. There are some who hold festivities at the full moon to praise her."