This episode marked the first appearance of Nicholas Lea as Alex Krycek. Carter had much interest in Krycek, because he replaced Dana Scully as Mulder's new partner. Lea had previously appeared as a different character in the first season episode, "Gender Bender." Bowman, who had directed "Gender Bender," thought that Lea "was a [...] strong choice for a fresh-out-of-Quantico FBI agent." When creating him, the writers always had in mind that he would be a recurring character, while they agreed if the character did not work they would kill him off.