[11] When auditioning for the role of Marita Covarrubias, Laurie Holden was not allowed access to an episode script, instead simply being told that her character worked for the United Nations and had an air of "intelligent seriousness".

[10] Holden was required to learn Russian for the episode "Patient X", and commented that roughly fifteen seconds of screen-time took hours to rehearse.

[13] The voice coach responsible for instructing Holden and Nicholas Lea in their Russian dialogue tested their proficiency by asking them to speak to Russian-speaking friends of his over the telephone.

[14] Holden felt that the two-part episode "Two Fathers" and "One Son" offered her "cold, emotionless, private" character a chance to come across as "vulnerable, exposed and raw".

Having been given the location of a downed UFO, she and Krycek betray The Smoking Man, instead going to FBI assistant director Walter Skinner and Mulder to inform them about the craft.

[26] Debra Warlick, writing for Cinefantastique, felt that Holden's acting in "One Son" was "heart breaking [sic]", but found that she had "unfortunately" been used simply to convey a plot point to other characters.

[27] Also writing for Cinefantastique, Paula Vitaris noted that Covarrubias "is a problematic character", adding that "she never breaks out of her function as a plot device".

[29] Writer Frank Spotnitz has described Covarrubias, along with Alex Krycek, as "young, attractive, vital [and] dangerous" compared to the other, older, characters working for the Syndicate.