Tory Foster is a Cylon that was first encountered on board Colonial One as aide to President Laura Roslin, succeeding Billy Keikeya who died on Cloud 9 by terrorist hands. Prior to discovering her true nature, she aids Roslin in hiding Hera from both Sharon Valerii and other Cylon agents in the fleet. Later, Foster (with the aid of Colonel Saul Tigh, Petty Officer Anastasia Dualla, and other Galactica crew), attempt to steal the first post-Fall election, thus trying to prevent Gaius Baltar from ascending to the presidency. After this bid fails, she becomes Roslin's aide on New Caprica, initially helping to teach children until the Cylon occupation of the planet, where she aids the resistance movement in organizing evacuation drills (under the guise of natural disaster drills) and accumulating information on members of the New Caprica Police. She is also tasked with getting Hera and her adoptive mother safely off the planet, but she fails to do so.
After reuniting with the Fleet, she resumes her post as Roslin's presidential aide, eventually working on the trial preparations for Gaius Baltar's tribunal. During Baltar's trial, she begins hearing strange music and a sexual relationship with the widowed Samuel Anders, only to discover that they are Cylons. Ever since, she has been the first to accept her Cylon nature, preventing Callandra Tyrol from killing the second-known Cylon hybrid child (choosing instead to kill Cally herself), and attempting to convince other members of the Fantastic Four to accept their Cylon natures.