One DS9 speculative script and multiple unused stories were devised by Christopher L. Bennett. He recalled, "My DS9 spec script actually got me a pitch invitation. I went out to L.A. and pitched to Robert Hewitt Wolfe; he didn’t take any of my pitches, but his comments about them drove home the importance of focusing on character, a lesson that’s been very helpful to me." (Voyages of Imagination, p. 146)
Three DS9 story ideas were conceived by Armin Shimerman, Eric A. Stillwell and David R. George III. Recalled Shimerman, "David George, partnered with Eric Stilwell, asked if I would join them to pitch episode ideas for Deep Space Nine. We worked for several months honing our plot points and eventually had our shot with writer/producer René Echevarria. Unfortunately, No sale." (Voyages of Imagination, p. 245)
Similarly, three story pitches were suggested by Gary Holland at a pitch session with Ira Steven Behr, Robert Hewitt Wolfe and Peter Allan Fields, toward the end of DS9 Season 2. Although one of these ended up as the genesis of DS9: "The Collaborator", the other two ideas were quickly dismissed by Behr, Fields and Wolfe. (Star Trek: Deep Space Nine Companion, p. 147)
A crossover between Deep Space Nine and Star Trek: The Next Generation was originally considered as one way to conclude DS9's first season. In the story, the two crews would have opposed an intergalactic invasion force. The plot was vetoed by Rick Berman. (Cinefantastique, Vol. 24, Nos. 3/4, p. 108)
Day at Quark'sEdit
Ferengi prejudice storyEdit
One of the three story ideas submitted by Armin Shimerman, Eric A. Stillwell and David R. George III dealt with prejudice and Ferengi. Referring to this plot concept, Shimerman noted, "Of the three pitch ideas, I gravitated to the one that was most interesting and upsetting." At Shimerman's suggestion, he and George turned the pitched story into the novel The 34th Rule. (Voyages of Imagination, p. 245)
Ron Moore's original concept for DS9: "Soldiers of the Empire" was for Worf and the crew of the Rotarran to enter Gre'thor. (Star Trek: Deep Space Nine Companion) While ultimately unused in DS9, this concept was later developed into VOY: "Barge of the Dead". (AOL chat, 1999)
In 1997, Ira Steven Behr commented to Star Trek Monthly, "You know the Nausicaans? They'll be back, and we'll do a show about them being an enemy for an episode." ("On Things Past, Present and Future", Star Trek Monthly issue 30)
Persistence of VisionEdit
A story written by Robert Hewitt Wolfe for DS9 Season 2 was inspired by he and Ira Steven Behr having a discussion about virtual reality, Behr asking, "How scary is it going to be in the future when you won't be able to tell what's real and what isn't?" Wolfe's subsequent story had Miles O'Brien and Jadzia Dax entering a virtual reality prison. The pair seem to escape but then realize they are still in the prison. "Then they escape again," Wolfe related, "and I wanted the tag to be where Keiko was telling O'Brien how good it was for him to be back, and O'Brien saying, 'I don't know whether I'm back or not. I'm never gonna know.' Fade out."
Michael Piller forced Robert Hewitt Wolfe into discarding the story, instead writing the similar Season 2 episode "Shadowplay". Although both stories feature the character of Rurigan, "Persistence of Vision" focuses more on him and is considerably more downbeat. Some of the plot was reused in third season opening two-parter "The Search, Part I" and "The Search, Part II". (Star Trek: Deep Space Nine Companion, pp. 122-123) Additionally, the title "Persistence of Vision" was reused for an installment of Star Trek: Voyager.
A story that never made it in the script stage would have a swarm of space locusts heading for Bajor, the Bajorans unwilling to defend themselves because prophecy foretold the event. The staff never found a way to make the locust angle non-goofy, but locusts were eventually included in "Rapture" as a sort of in-joke. (Star Trek: Deep Space Nine Companion, p. 306)
Sito Jaxa returnEdit
One story considered by the writing staff concerned the return of Sito Jaxa from TNG: "Lower Decks". The pitch had Sito being imprisoned under inhumane conditions and suffering from post-traumatic stress disorder. Robert Hewitt Wolfe developed the story for some time. Feeling that there was insufficient explanation of Sito's condition, he had Sito killing her cellmate, whom she'd become close to. (Star Trek: Deep Space Nine Companion, p. 326) According to Ronald D. Moore, "We talked about this for quite awhile, but then decided that bringing Sito back would rob 'Lower Decks' of a great ending." (AOL chat, 1997)
Thomas Riker returnEdit
After "Defiant", Jonathan Frakes lobbied the producers to bring back Thomas Riker for a sequel episode. Frakes noted, "I keep thinking Tom is coming back [....] Don't you think it makes sense for them to send Kira over there to free Thomas? It's a no-brainer." Frakes, however, received no definite indication from the producers. (Star Trek: Deep Space Nine Companion, p. 191)
The Star Trek: Deep Space Nine Companion (pp. 191-192) states that, in the fourth season pitch letter sent to freelance writers, Thomas Riker was listed as a subject that the producers were not interested on hearing about. However, the authors note that this could have meant that the producers were already working on such a story. Several comments from Ronald D. Moore indicate that the writers did seriously consider the possibility. In the 1996 book Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, Moore commented, "We'll probably see a return-of-Tom Riker episode. What's nice is he's not really a part of Next Generation, so he's ours, and we can do what we want with him and not worry about what the movies do with Will Riker." (p. 87) Likewise, in an online chat with fans, Moore noted, "Tom Riker may or may not get rescued at some point." (AOL chat, 1997)
In an interview with Jonathan Frakes provided with the TNG Season 6 DVD box set, he states that he had approached Moore regarding a Thomas Riker episode involving Damar's rebellion. However, the character never appeared again.
Ronald D. Moore advocated doing a musical episode. "Oh, and I was agitating for a musical, man," he stated. "On record, I wanted to do a musical version of Trek well before Buffy or Chicago Hope. I wanted to do a musical episode, and nobody would f***in' do it." When the interview spoke of how this was accomplished on Buffy the Vampire Slayer, Moore responded, "Yeah, that's all we needed to do. There's just some tech virus that infects the crew and they can only communicate in song, you know? And just do it! And have a ball. That was part of the struggle on Next Gen, too, was to just have fun. 'Can we just do a laugh for an episode? Where it's not so serious, where we [don't] have to put the ship in jeopardy every week, where someone's life hangs in the balance. Let's just do a comedy episode.' And that was a real – they fought against it and fought against it and fought against it." 
Jack Treviño and Toni Marberry sold three stories to Deep Space Nine, but only two were filmed. The third story, sold about a year after the team sold "Little Green Men" and "Indiscretion", was called "Quorum". However, it went unproduced.