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Doctor Cyrus Xander is Daniel Graystone's assistant at Graystone Industries 58 years before the Fall of the Twelve Colonies. Sometime prior to relocating to Caprica, Xander witnessed or heard of authorities on his home colony arresting suspected enemies and causing them to disappear forever (CAP: "Apotheosis").
Xander interfaces with the Ministry of Defense on the U-87 Project that begets the creation of the Cylon prototype. He worries that the contract for U-87 project would go off world to Tomas Vergis, after discovering that Vergis Corporation successfully created a meta-cognitive processor. He is present at the demonstration of the Cylon prototype to Joan Leyte, the new Caprican Minister of Defense (CAP: Caprica pilot) and later informs Daniel that the original prototype is the only machine to be self-aware and possess true, adaptive artificial intelligence (CAP: "Rebirth").
Sometime afterward, Xander takes on the role of defender and personal supporter for Daniel. In the wake of Amanda Graystone's public statements about their daughter's involvement in the Maglev bombing, he arranges for Priyah Magnus to consult Daniel on a public relations strategy (CAP: "The Reins of a Waterfall"). At a meeting of Graystone Industries senior executives, Xander responds to demands for Daniel's removal by reminding them that "Daniel Graystone is the brand" and that removing him would be suicide for the company (CAP: "There Is Another Sky"). Xander is dismayed and angered to hear that Daniel used Ha'la'tha to steal the meta-cognitive processor, but eventually calmed and offered guidance on how he should talk with Tomas Vergis and deal with Vergis' accusations (CAP: "Know Thy Enemy"). As problems mount and Vergis takes the CEO position from Daniel, Xander remains loyal to Daniel, keeping the ruined remains of the original U-87 despite Vergis' order to scrap them, and reporting to Daniel on developments inside Graystone Industries (CAP: "End of Line," "Unvanquished").
Following Daniel's reinstatement as CEO, Xander becomes involved in the development of advertising for Grace software, using Daniel's image without prior permission. He later brings to Daniel's attention irregularities in U-87 production and shipping, eventually leading to the discovery of combat robots being diverted by the Ha'la'tha to new customers - the Soldiers of the One on Gemenon (CAP: "False Labor").
Xander is in the process of leading an investigation of and a response to an attack on Daniel and his wife in their home, when Director Gara Singh and Global Defense Department agents arrive to arrest the Graystones. Suspecting that Singh has created a pretense for secretly detaining or killing the Graystones, Xander produces a pistol and holds the GDD personnel at bay, giving Daniel, Amanda, and their bodyguard Sean a chance to escape. Xander's fate after this incident is unknown (CAP: "Apotheosis").