of an experiment attempting to achieve purity within a species. Executive producer Michael Piller described the draft as originally focusing on "somebody's idea that this could be the result of a hideous concentration-camp kind of experiment, that is, genetic demonstration of some sort". Biller and executive producer Jeri Taylor were critical of Glassner's pitch; Biller found it to be "very melodramatic and hokey", and Taylor called it "a tired idea" and "too on the nose for B'Elanna". Producer Brannon Braga explained that the decision to purchase the concept was to do a storyline involving an evil twin in the show's first season, and "get it out of the way". He did feel that the concept could be a mistake, and compared it negatively to a hypothetical storyline in which Star Trek: The Next Generation character Data (Brent Spiner) would be made human. Piller said the episode was almost abandoned, but he believed that the conflict between Torres' human and Klingon halves, and her identity as a woman, would make a worthwhile storyline. Writing The series' writing team were concerned that the episode would be compared to two episodes from Star Trek: The Original Series ("The Enemy Within" and "The Alternative Factor"). Piller added: "[w]e knew we could not do the evil-versus-good story that the original Star Trek had done." Biller was assigned to write the script as his second writing assignment for the series; his first had been for "Elogium". Biller attributed his interest in the episode's concept to his personal experiences with his younger, adopted brother's struggle to understand his biracial identity. Even though Biller was initially critical of the pitch's melodrama, he felt that his version had the melodrama expected of a Star Trek episode. The final draft of the script was submitted on February 24, 1995. Biller incorporated the Vidiians into the episode, believing that their technology would present a conceivable method by which Torres could be separated. The Vidiians were featured in an earlier season one episode titled "Phage". Biller explained that Klingons were shown to be more resistant to disease than other species in previous Star Trek installments, and reasoned that a Vidiians scientist would view them as a promising way to discover a cure for the disease. Biller said that he had difficulty writing Sulan as a sympathetic villain. He looked to Gene Roddenberry's approach to portraying antagonists in the Star Trek franchise: "[A]liens