Aion is a character in the backstory of Legend of Mana. Formerly the King of the Faeries, he raised an army to battle the Great Witch Anise and her mages, but Aion and his Faeries were defeated and forced to live in the realm of men. However, they came to realize that not all humans were evil, and formed an alliance with the good ones to fight in the Holy War of the Mana Tree.
The stakes of the war were immense. The Mana Tree was burned to the ground, Anise was killed by the power of the Faeries' Seventh Stone, and Aion was banished to the Underworld. He became the Lord of the Underworld after refusing to reincarnate, and created the Shadoles to guide the spirits of the departed to his realm. The Faeries over whom Aion once ruled remained in the realm of men, and came to harbor a deep hatred for humanity.