Sharon "Boomer" Valerii

Junior Lieutenant Sharon "Boomer" Valerii was a Humanoid Cylon, one of many identical Number Eight copies. She was infiltrated into Colonial society as a sleeper agent, her knowledge of her Cylon nature suppressed and replaced with false memories of a human life, the better to serve undetected aboard the Battlestar Galactica. Her gradual awakening to her true nature led her to shoot Commander William Adama and then to her own death at the hands of a crewman. Resurrected, she became a tool of the Number Ones, played a part in the events that triggered the Cylon Civil War, and met her final death at the Colony. She is distinct from the Caprica copy who took the callsign "Athena" and married Karl Agathon. (Battlestar Galactica (miniseries); Battlestar Galactica, "Kobol's Last Gleaming, Part 2"; "Daybreak, Part 2")

A planted life#

Before being sent to infiltrate Colonial society, Valerii was given false memories of a human upbringing; as far as she knew, she had been born on the mining colony of Troy to a family from Aerilon. Stationed on Galactica as a Raptor pilot, she fell into a romantic relationship with deck chief Galen Tyrol, a breach of regulations that the two believed was discreet but that was widely known aboard ship. Her face belonged to every Eight, one of twelve humanoid lines covered in our guide to the Cylon models. (Battlestar Galactica (miniseries); Battlestar Galactica, "Flesh and Bone")

Awakening#

After the fleet's escape from the Cyrannus system, the Cylons tracked it down every thirty-three minutes, an ordeal that exhausted Galactica's pilots. Valerii showed little fatigue, flying Raptor support with her new Electronic Countermeasures Officer, Lieutenant Alex "Crashdown" Quartararo. She was soon contacted by a circle of Humanoid Cylons hidden among the survivors, led by a Number One posing as a priest aboard Galactica. Urged to take her own life before she was implicated, she refused, expressing instead a longing for her human persona and loneliness in her Cylon nature. (Battlestar Galactica, "33"; "Water"; Battlestar Galactica: The Plan)

Signs of her true self mounted. She woke soaking wet after the water tanks were sabotaged, found the word "CYLON" written on her locker mirror, and confessed her suspicions to Tyrol. Fearing what she might do, she had Baltar test her with his Cylon Detector; the test came up positive, but Baltar kept the result to himself out of fear she would kill him. Her condition worsened until, convinced she was about to commit some terrible act, she put a gun to her mouth and fired, but her Cylon side pulled the shot away and she survived. (Battlestar Galactica, "Water"; "Six Degrees of Separation"; "Flesh and Bone"; "Kobol's Last Gleaming, Part 1")

Her hidden programming ultimately compelled her to shoot Commander Adama after completing a nuclear strike on a basestar over Kobol. Held in the brig and questioned about how many Cylons were in the Fleet, she refused to talk, shifting between personas even as Colonel Saul Tigh beat her. She was killed shortly afterward by deckhand Cally, dying in Tyrol's arms. (Battlestar Galactica, "Kobol's Last Gleaming, Part 2"; "Resistance")

Resurrection and New Caprica#

Valerii's consciousness downloaded into a new body, and she tried at first to resume a human life on Caprica, resisting identification with the Cylon cause even as the Cylons hailed her and Caprica Six as heroes. Opening up to Six, who had likewise been changed by love for a human, she resolved to persuade the Cylons that some of their actions had been wrong, despite a Number Three's threat to have them boxed. Her rebirth and her first days back on Caprica are the heart of the episode "Downloaded". (Battlestar Galactica, "Downloaded")

Boomer was among the Cylons occupying New Caprica, where she accepted herself as a Cylon and served on the governing council overseeing the puppet government of President Gaius Baltar. Her hope of human-Cylon coexistence persisted, but relations between the two peoples only worsened. (Battlestar Galactica, "Occupation"; "Precipice")

Second death#

Boomer was later seen trying to care for the ailing hybrid child Hera, frustrated by her inability to bond with the girl. When Athena arrived aboard the basestar and was reunited with Hera, Boomer grew increasingly distressed, accusing her of always intending to take the child. Declaring that the failure of New Caprica proved humans and Cylons could not coexist, she threatened to break Hera's neck, and was killed for it when Caprica Six snapped her neck to protect the future of the Cylon race. (Battlestar Galactica, "Rapture")

Cavil's instrument#

Resurrected once more, Boomer developed a relationship with the Number One, John Cavil, who embraced his machine nature and despised human traits as weakness. When the Cylons deadlocked over a plan to reduce the sentience of the Raiders, Boomer cast her vote in favour, becoming the first Cylon ever to vote against her own model. After Cavil's faction began killing the opposing Cylons beyond the reach of a Resurrection ship, she had doubts about the deaths of her fellow Eights, but Cavil pressed her to let go of her human traits and become a better machine. (Battlestar Galactica, "Six of One"; "The Ties That Bind")

Cavil alone confided in her that he was holding the Cylons' creator, Ellen Tigh, prisoner. When the Resurrection Hub was destroyed and Cavil threatened to cut open Ellen's brain for her knowledge, Boomer spirited her away by Raptor, telling her she forgave her. On arrival at Galactica, Tyrol identified her and she was taken to the brig. (Battlestar Galactica, "No Exit")

Final death#

The rebel Cylons resolved to try Boomer for treason, with execution possible now that Resurrection was lost. She professed her continued love for Tyrol and shared with him a projection of a dream home on Picon where they were married with a daughter. Convinced she would be condemned, Tyrol helped her escape. (Battlestar Galactica, "Someone to Watch Over Me")

Boomer then beat Athena and hid her, bound, in a bathroom. Putting on a pilot's uniform, she was found by Karl Agathon, who, mistaking her for his wife, began to seduce her; after first trying to leave she went through with it. She drugged Hera, concealed her in a supply case, and smuggled her aboard a Raptor. Warned by Adama that he would shoot her down, she flew out under fire, clipping a wing and damaging Galactica with the spatial disruption of her jump. Ellen later concluded that everything Boomer had done, including the rescue, had been planned to deliver Hera to Cavil. (Battlestar Galactica, "Someone to Watch Over Me"; "Islanded in a Stream of Stars")

Aboard the stolen Raptor, Boomer could not bring herself to sedate the crying Hera, and instead bonded with her over the shared projection of the Picon home, discovering the child could project as well. She delivered Hera to Cavil, but doubts remained. When the Colonials assaulted the Colony and the Cylon Simon refused to stop examining Hera, Boomer killed him, carried the child to the rescue party, and returned her to her parents. Athena would not forgive her. Boomer said she had known this would likely be her last act, and that she owed a debt to the Admiral, who had not cast her out of the fleet when she repeatedly failed to land properly. Athena then shot and killed her; with Resurrection gone, the death was final. (Battlestar Galactica, "Islanded in a Stream of Stars"; "Daybreak, Part 1"; "Daybreak, Part 2")