The episode title, "One Breath" comes from a line from Scully's father when he talks to her during the episode. The character 'The Thinker', who later appears in person in the episode "Anasazi" was named after online X-Files fan 'DuhThinker'. The episode introduces Melinda McGraw as Scully's sister Melissa. McGraw had previously worked with writers Glen Morgan and James Wong, who specifically wrote the part with her in mind. Thoughts were given to having a romantic interest between Mulder and Melissa, but the concept never came to pass.