Kes joins the crew in the pilot episode "Caretaker", opening an aeroponics garden and working as the medical assistant to the artificial intelligence known as the Doctor.

Voyager's creators Rick Berman, Michael Piller, and Jeri Taylor designed Kes to be a rapidly-aging character who would provide audiences with a different perspective on time.

At the time, this was not openly discussed and her departure was attributed to other reasons; these ranged from Lien voluntarily leaving to pursue other roles to her being removed to make room for Jeri Ryan's introduction as Seven of Nine.

Reviewers and fans disliked her return in the season six episode "Fury", which some media outlets called one of the worst moments in the Star Trek franchise.

Introduced in Star Trek: Voyager's pilot episode "Caretaker", Kes is an Ocampa—a telepathic alien species with latent psychic abilities and a life span of nine years.

Leaving on a shuttlecraft, she hurls Voyager and its crew safely beyond Borg space, roughly 10,000 light-years closer to Earth, before turning into living energy.

[30] Nathan Archer began writing the 1995 book Ragnorak, before the pilot episode aired and said that his interpretation of Kes, based on the series bible, was radically different from her depiction in the show.

[31] She goes back in time to help create an Ocampa and Nacene hybrid in the String Theory trilogy (2005–2006) by Jeffrey Lang, Kirsten Beyer, and Heather Jarman.

[25] Kes is also depicted in short stories,[33] like Penny A. Proctor's "Restoration" from the 2002 anthology Star Trek: Strange New Worlds V in which she revives Ocampa's ecosystem.

[34][35] Inspired by the Star Trek: The Next Generation episode "The Child", Berman, Piller, and Taylor wanted to feature a rapidly-aging character to encourage viewers to reflect on time.

[41] In initial descriptions, Kes was characterized as a potential scout and expert on gangs,[41] but was later changed to be a medical intern,[35] while Neelix assumed a similar role as a guide.

[42] When Berman, Piller, and Taylor wrote Kes with psychic powers, production assistant Zayra Cabot hired a paranormal-focused consulting firm, Joan Pearce Research Associates.

[37] The "Caretaker" script describes her as a "dazzling, ethereal beauty, waifish and fragile" who has a "dignity to her bearing, an alertness in her look, that suggests a being of powerful intelligence".

[55] While promoting Voyager, Lien said that Kes lacked any "cynicism or precociousness or pretentiousness or sarcasm", and believed this separated her from the typical roles for young women.

[62] In retrospect, writers and producers felt Kes and Neelix never worked as a couple;[58] a break-up scene was filmed for the episode "Fair Trade", but was cut due to time constraints.

[50] In a 2010 interview, Lien said she preferred "The Gift" as her final episode; she disliked her performance in "Fury", explaining that she had not acted for an extended period and struggled with playing such a different version of Kes.

[90] Bustle's Marie Southard Ospina praised "Elogium" for its portrayal of a woman voluntarily not having a baby, but felt that Kes's age made the moment uncomfortable.

[94] Science fiction author Sylvia Spruck Wrigley interpreted Kes as undergoing puberty in "Elogium", noting that it raises questions about Neelix starting a relationship with a prepubescent girl.

[25] Michael Weyer of Comic Book Resources believed that Kes deserved a better ending and disliked how she came back as "twisted monster whose actions can come off as a spoiled brat".

[104] She identified Kes as one of several female characters with similar characteristics on Star Trek who are placed in healthcare rather than leadership roles, and argued that this is because the setting of the series "valorized" masculine traits over feminine ones.

[105] American culture historian Peter W. Y. Lee said that Voyager characterizes Kes as a "little girl" who struggles to maintain her innocence as the series progresses,[106] specifically with scenes involving sex or motherhood.

[107] Lee wrote that unlike other children in Star Trek, namely Wesley Crusher, Jake Sisko, Nog, Molly O'Brien, and Alexander Rozhenko, Kes is more of a "blank slate".

[108] He argued that Kes becomes too mature for this "little girl" role after adopting a "more aggressive womanhood and sexuality" in "Warlord" that foreshadows her having "outgrown her home" and leaving Voyager.

Garcia-Siino wrote that although these events shaped the writing for Kes, the character was still portrayed with authority through her hydroponics garden and her medical and psychic training and is shown as reaching self-actualization.

Cultural studies lecturer Debra Bonita Shaw argued that although Janeway accepts characters like Kes into her crew, she treats them as subordinates who must aid in Voyager's return home.

[114] According to Kaufman, it was shown in their protection of each other, like Janeway saving her in "Sacred Ground" and "Fury", and Kes sending Voyager's crew past Borg space in "The Gift".

[118] Aviva Dove Viebahn, a professor of media studies, argued that the non-human Kes is nearly tokenized as a "native informant" whose role is merely to advise the human crew about the Delta Quadrant.

For Viebahn, the character's mental abilities, which at times are more useful than Voyager's medical and scientific technologies, provide her a degree of agency which elevates her from this "subjugated" role.

[119][120] Media studies scholar Marion Gymnich wrote that in "Cold Fire", Kes changes from "generally very friendly and gentle" to "extremely destructive" after being tutored by another Ocampa.

Tembo wrote that Kes and Circe both have the "attractive and equally dangerous aspects of Aeaea and Ocampan power are under the absolute control of a female authority".