She assumed the surname Bannings during the imperial occupation of Crossbell.
When KeA is found by Lloyd Bannings and the Special Support Section during the Schwarze Auktion on Mishelam, she appears to have lost her memory. Her outspoken character and innocence makes her loved by everyone and she herself easily befriends all of the S.S.S's associates.
It is later revealed that KeA is actually a homunculus cultivated as a reproduction of the Sept-Terrion of Mirage, Demiourgos, by the Crois family's lineage of alchemists. She was named KeA, derived from the idea that she would become the key to the origin of everything (all), "Key of A".
After creation, KeA has continuously slept for 500 years on the altar of the D∴G Cult. The Cult, not knowing KeA's true purpose, was led into believing KeA was the daughter of the true Goddess, as opposed to Aidios. Following the Crois family's commands, however, Arios MacLaine was tasked with removing KeA from the altar and hide her at the Schwarze Auktion. It was by KeA's decision as the Sept-Terrion of Zero that she wanted to be protected by Lloyd.
Upon KeA's completion as the Sept-Terrion of Zero, she had not only inherited governance over mirage, but the two other higher elements - time and space - as well. This means that KeA possessed a terrifying power that allowed her to read and overwrite past, present and future alike. She merged with the Azure Tree and became the Azure Demiourgos.
When the Special Support Section beat the Azure Demiourgos and released KeA from the spell, she lost her raison d'être and began to follow the footsteps of the original Demiourgos by wishing herself out of existence. Lloyd, however, interrupted the process by breaking into KeA's inner world and told her that to spend time with him and the S.S.S, she would not be needing the powers she had just lost.
KeA loses her powers and becomes an ordinary girl.