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Past as one of the Final Five
Like the other Final Five Cylons, Tory is a Thirteenth Tribe scientist re-inventing Cylon resurrection technology on Earth. She cohabitates with her lover, Galen Tyrol. When nuclear armageddon comes, she downloads to a resurrection ship the five had placed in orbit, having been warned of Earth's impending doom by messengers invisible to other people.
She and her cohorts travel at relativistic but subluminal speed to warn the other Twelve Tribes (i.e., humanity) about the dangers of creating artificial life in order to avoid another revolt and horrific war. They follow the sign-posts left by the 13th Tribe, such as the Temple of Hopes. Tory and the others arrive during the First Cylon War, too late to have prevented it. They are, however, able to end the war by agreeing to help the Centurions develop humanoid Cylons, a project on which the Centurions had started with little success.
Tory and the other four of the Final Five create eight humanoid Cylon models copied many times over. Number One becomes jealous of the others, particularly Number Seven, and dissatisfied with the body and programming the Final Five gave them. After eliminating the Number Seven line, Number One kills Tory and the other four. He controls their resurrection to repress their memories, and maroon them among the humans, unaware of their true nature. (No Exit)
Roslin's loyal aide
Prior to the Cylon attack, Tory was precinct captain for the Federalist Party in Delphi for five years, where she became proficient at taking polls (The Captain's Hand). During the Cylon attack, Tory was driving down a road on Caprica talking on her cell phone when the bombs hit. Tory was hit by a nuclear shockwave and while she was injured, her car (which was destroyed) protected her enough for her to survive and she was apparently rescued by a Raptor that landed nearby looking for survivors (The Plan). President Roslin taps her to replace the late Billy Keikeya as Presidential Aide.
When President Roslin makes the decision to keep the new-born Cylon/human baby as far away from Sharon Agathon and the Cylons as possible, Tory creates a list of hand picked civilians who could be trusted with the baby. In the end a civilian named Maya is selected to take custody of the child. Tory makes it very clear that the child's mother's identity must remain a secret (Downloaded).
Tory later conspires with Saul Tigh and Anastasia Dualla to rig the Presidential election in Roslin's favor. The ruse is uncovered and suppressed by Admiral Adama and Lieutenant Gaeta (Lay Down Your Burdens, Part II). During the occupation of New Caprica, Foster aides Roslin in compiling a list of humans who are in collusion with the Cylons. Roslin makes her responsible for ensuring the safe transport of Maya and Hera off the planet, but she fails at this task. Maya is killed trying to escape New Caprica with the child. Hera survives but is found by the Cylons ("Occupation", "Exodus, Part I & II").
Before and during the trial of ex-president Gaius Baltar, she is tasked with helping Roslin assemble a tribunal to bring charges against Baltar, as well as establish security arrangements ("The Woman King", "The Son Also Rises", "Crossroads, Part I"). She demonstrates an unwillingness to aid Romo Lampkin's defense case through initially stonewalling Lampkin's attempts to gain access to records on Colonial One (The Son Also Rises).
Revelation as a Cylon
Some time after the apparent death of Kara Thrace (Maelstrom), Foster began a sexual relationship with Thrace's widowed husband, Samuel Anders. Roslin apparently learns of the relationship and is displeased (Crossroads, Part II). At the beginning of Baltar's trial, Foster begins to show signs of stress, possibly originating from a strange noise which she hears as the Fleet moves towards the Ionian nebula. Her lack of sleep and stress levels results in a damaging outburst to the press corps during the press conference at which Roslin discusses the return of her cancer. Roslin confronts Foster after this, threatening to replace her if she does not get back on her game (Crossroads, Part I). When the Fleet reaches the nebula, Foster (on Galactica) is drawn to Saul Tigh, Galen Tyrol, and Samuel Anders, who also hear the now-coherent melody. Despite each of them realizing that they are Cylons, Foster and the others re-commit themselves to the Colonial cause. Foster returns to CIC and stands by Roslin, ready to aid (Crossroads, Part II).
The four newly revealed Cylons try to keep their nature hidden from those around them, while trying to come to terms it. When they brainstorm ideas about the still-missing final Cylon, Colonel Tigh suggests that Foster flirt with Gaius Baltar to gain access to the knowledge he acquired while living among the Cylons. Although initially repulsed at the idea, she speaks to Baltar and is slightly captivated when he explains how he sees his new role as religious figure. Although at first she cries when eventually sleeping with him, she is further charmed when Baltar tells her that he thinks Cylons are people with feelings too (Six of One).
Foster also tries to hit on Galen Tyrol, who rebuffs her advances but is suspected of having an affair by his wife. After one of their clandestine meetings, Foster notices an open wall covering, and concludes that they have been overheard by Cally Tyrol, who must have found a note by Tigh to her husband. Not long after that, she follows her to a Viper launch tube where Tyrol is about to kill herself and her son by expelling them out of the tube into space. Foster confronts Tyrol and explains that they only recently found out they were Cylons, and that they are still the same people, as scared and confused as everyone else. Foster comforts Tyrol and takes Nicky in her arms, then suddenly strikes her, throwing her body into the air. She retrieves the launch tube key, exits the launch tube with Nicky in her arms, and uses the key to activate the launch controls. As Tyrol regains consciousness, Tory opens the outer airlock door, sending her to her death in open space (The Ties That Bind).
Foster shows no guilt over this. She appears to have embraced both being a Cylon and her own version of Baltar's teachings, allowing her to by-pass such feelings and adopt an almost hedonistic approach to life. She declares herself to be "perfect", something that uneases fellow Cylons Tigh and Tyrol, and is in marked contrast to Tigh's and Caprica-Six's guilty consciences (Escape Velocity).
After Downloaded Three is unboxed, now knowing the identities of the Final Five, and brought to Galactica, Foster stays true her earlier affinity for her Cylon side. Under the pretence of bringing Laura Roslin her medication, she flies to the Cylon basestar, where she is introduced to her fellow Cylons and tells Roslin and Baltar about her true nature. During the ensuing stand off between Three and Galactica over the remaining three Cylons, she helps Three's cause by informing her of Lee Adama's perceived weaknesses (Revelations).
When the fleet arrives at Earth and discovers it is a barren world rocked by a nuclear catastrophe and once populated by Cylons, Foster and her fellow Final Five Cylons begin remembering details about their past lives on the planet. One detail she clearly remembers is how Anders used to be a musician and used to play a song he wrote for her and their friends, Galen Tyrol and Saul and Ellen Tigh. She and Tyrol were also lovers at the time (No Exit).
Since being publicly identified as a member of the Final Five Cylons, Foster has taken up full time residence on board the rebel basestar, living with the Twos, Sixes (less Caprica-Six), and Eights (less Sharon Agathon & Sharon Valerii). Her fellow Cylons appear to have also given her equal status in their command hierarchy, as evident by her behaviour during Gaeta's Mutiny. When Laura Roslin is smuggled aboard the basestar, Foster is content to abandon the fleet to its own turmoil and simply jump away to safety, a notion her fellow Cylons support. Though she repeatedly argues against involving the basestar in the counter-coup efforts, she ultimately concedes to Roslin's plan (Blood on the Scales).
During Gaeta's mutiny Sam Anders is shot in the back of the skull. When he regains consciousness he remembers his and the others former life on Earth and after. He recites the history as fast as he could to the other Final Five, including Tory Foster. Like the other Fives she was a scientist attempting to reinvent resurrection technology. To her and Galen Tyrol's mutual shock she learned that they were once lived together as lovers and were engaged to be married. (No Exit) After Anders's apparently unsuccessful surgery (in terms of his regaining consciousness) and his comatose state, Foster urged the other Finals and Caprica-Six to leave for the baseship and leave the fleet to strike out on their own without humanity. Then Ellen Tigh the Fifth Final arrives after a so-called rescue of her from Cavil by Sharon Valerii. Arguments of the merits of staying with the fleet and leaving are exchanged and it comes to a vote Tyrol and Foster vote to leave, Tigh votes to stay. While he was presently in a coma Tyrol assumes that Anders would had voted to stay based on his emphatic plea to Col. Tigh to stay with the fleet. It made the vote a 2 to 2 deadlock with Ellen Tigh the deciding vote. At the time she didn't know how she would vote as she was also disturbed by personal revelations of the relationship between Col. Tigh and Caprica-Six. Later, born out of jealousy, resentment and vengeance over Saul Tigh having a child with Caprica-Six and the implication that he loved Caprica-Six more than he ever did Ellen, Ellen voted to with Foster and Tyrol to leave humanity, making it a 3-2 result. However Caprica-Six miscarriage, brought on possibly by stress caused by an attack in Dogsville earlier and personal confrontations with Ellen Tigh over the true love of Saul Tigh. Foster like the others stay since Hera Agathon became the only hope of the Cylons. (Deadlock)
As the Five recover over the tragedy of the miscarriage, Tory commiserates with the others including a desperate Tyrol for the life of Boomer who was about to be transported for trial on the baseship. She agrees with Ellen Tigh that they cannot interfere with Cylon due process other than being witnesses. Then she was present when Kara Thrace played the song on the piano in Joe's Bar that switched them on in the nebula. She confronts Thrace as to were she learned that song. Thrace told her it was a song that her father played for her as a child. Later off screen she told them that she was playing the music notes written as a drawing by Hera Agathon. By this time Sharon Valerii had already taken Hera and escaped. (Someone to Watch Over Me)
She was later present with Saul Tigh, as Ellen Tigh urged the Adamas to search for Hera at the Cylon Homeworld. Kara Thrace also stresses that they should search of Hera. Tyrol, although not revealed in the aired episode, was arrested for his aid in the escape of Valerii and the abduction of Hera so he was not present. At that meeting Foster didn't render an opinion vocally but she agreed with Ellen's assertions and helps arrange the Heavy Raider reconnaissance mission after Adama gives his permission. (Islanded in a Stream of Stars)
Ellen Tigh volunteered the Final Five to go on the mission to rescue Hera, much to Tory's dismay. Tory and her Cylon siblings remained on Galactica to control Sam, who is plugged into Galatica's system. (Daybreak, Part I)
She remains there for the battle, and is standing next to Sam when Caprica-Six and Gaius Baltar fulfill the Opera House Prophecy, rescuing Hera and seeing the Final Five. When Cavil invades Galactica's CIC to take Hera back, Tigh volunteers to give him Resurrection technology, which requires the Final Five to share their memories. The shared memories reveal to Tyrol and the others that it was Tory who killed Cally. An enraged Tyrol breaks the connection and grabs her by the throat, choking her and breaking her neck. With the destruction of the Resurrection Hub, her death is permanent (Daybreak, Part II).