Edea Kramer is initially presented as a power-hungry sorceress who seizes control of Galbadia from President Deling. Her motives are unknown, but SeeD is dispatched to assassinate her. Later, it is revealed that Edea is actually the wife of Headmaster Cid,and was known as "Matron" to Squall and the other kids that lived at the orphanage. It is eventually explained that Edea was not acting of her own will, but was possessed by a sorceress from the future named Ultimecia.
Source: Wikipedia, "[en.wikipedia.org/wiki/Characters_of_Final_Fantasy_VIII%23Edea_Kramer Characters of Final Fantasy VIII]", available under the CC-BY-SA License.