Summary

• Kes and Seven of Nine could have coexisted, creating an interesting conflict and invigorating Voyager's storylines.
• Kes' presence in later seasons would have given Captain Janeway an edge in battling Delta Quadrant aliens.
• Kes' potential dark turn and her telepathic abilities could have had significant impacts on the narrative and character development.

Star Trek: Voyager would have been different in its latter seasons if Kes (Jennifer Lien) had stayed on the USS Voyager instead of departing in Voyager season 4, when her ostensible replacement Seven of Nine (Jeri Ryan) arrives. There's no narrative reason both Kes and Seven couldn't have existed concurrently, especially since the differences between Kes' optimistic innocence and Seven's detached efficiency could have made for an interesting conflict that would still serve the purpose of invigorating Voyager's lagging storylines.
Kes' early development was bogged down by her relationship with Neelix (Ethan Phillips), but after the pair break up, they're both free to pursue independent character arcs. While Neelix becomes more interesting, Kes never gets a chance to do the same, despite hints of a potential dark turn for Kes that would have made her a memorable Star Trek:Voyager villain. Kes' presence in later seasons would also give Captain Kathryn Janeway (Kate Mulgrew) an edge in battling adversarial Delta Quadrant aliens like the Borg, Hirogen, and Species 8472. It's pure speculation, but consider the possibilities of an alternate timeline where Kes stays on Voyager.

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