When Star Trek: The Next Generation aired on television in 1987, the show had trouble finding its identity. The series was created in response to the ongoing success of the Star Trek franchise kicked off by the original series in 1966. The films were doing well, Paramount wanted to make another series, and they made it so. Trek creator Gene Roddenberry’s influence on the first few seasons of TNG, coupled with shifting showrunners and production responsibilities, led to a few awkward years of television before the show took off.

When The Next Generation was in its sixth season, it was proving to be a huge success—so much so that Paramount figured they may as well spin off the series yet again, taking the show in another direction with a new approach that wouldn’t detract from the appeal of still-ongoing TNG. Deep Space Nine (1993) was the first Star Trek series born completely without Gene Roddenberry’s input, created by TNG producers Rick Berman and Michael Piller, and its setting and concept gave it a very different tone and feeling from both previous installations in the Star Trek franchise.

Without guidelines prohibiting various forms of conflict, without restrictions about character behaviors, and without the setting of an active starship, Deep Space Nine was science fiction that was grounded in reality. Den of Geek goes so far as to call it the most realistic of all the Star Treks, as it “dug deeper into the themes that make Star Trek what it is than any other show in the franchise.“

This reality also made it a tonally darker show than its predecessors. Roddenberry’s utopian view of humanity is not as forced in DS9 as it was in those that came before it—and let’s be real—reality is much darker than Gene’s revolutionary but overly optimistic ideals. Interpersonal conflicts were commonplace on DS9.

Deep Space Nine’s story opens on the titular space station, which is in orbit around the planet Bajor. The station was once occupied by the Cardassians, from whom the Bajorans liberated themselves in a brutal and devastating war. The United Federation of Planets was invited by the Bajoran Government to establish a presence on the station, mediating continued peace between the two entities. Also nearby is a wormhole that bridges the gap between their section of the Milky Way and the Gamma Quadrant, an unexplored area of space previously inaccessible. Starting as a procedural show, DS9 contained story arcs that spanned episodes or even seasons, beyond the scale performed on TNG. It grew into a more serialized format that co-creator Michael Piller said allowed “repercussions of past episodes to influence future events and remain with the show, forcing characters to “learn that actions have consequences.”

As Den of Geek continues, “Deep Space Nine has always felt like black sheep of Star Trek. It is a much darker, and arguably more realistic vision of the future. It is a vision of the future unobstructed by rose-colored glasses. Maybe that’s why people have always had such strong opinions about it.”

After all, the series is founded in the wake of a war between an enslaving race of people and the slaves who revolted, deemed terrorists by their former captors. Hated and racism are prevalent throughout DS9, as the Bajorans and Cardassians are forced to tolerate one another’s continued existence in thematic examinations of colonization.

Not only that, but Roddenberry’s Star Trek envisioned a world free of disease and sickness. There’s sexual abuse and PTSD. There’s attempted genocide against “changelings” at the hand of the Federation. There’s a war replete with questionable tactics, both from the assailant and the Federation. And the series shows that, unlike in The Next Generation’s environment, not every interplanetary disagreement can be solved through application of the Federation’s politics (as in The Dominion War). The ethical dilemmas on DS9 are far more profound and internal than on previous series (i.e. the moral quandary of Sisko (Avery Brooks) allowing the Klingons to attack Cardassia unannounced), and reveal that sometimes the darker solution to a problem is the more appropriate one.

Morally ambiguous characters are also prominent on Deep Space Nine. While TNG had the occasional appearance by Q (John De Lancie), the mysterious and omniscient being with limitless power and questionably motivated interest in Picard’s (Patrick Stewart) crew, Deep Space Nine has morally ambiguous folks as part of its everyday ensemble - Garak (Andrew J. Robinson), Quark (Armin Shimerman), Kira (Nana Visitor) and Odo (Rene Auberjonois), to name a few.

This all isn’t to say that Deep Space Nine completely abandons the principles that defined Star Trek before its inception; the series still ends with a hopeful vision of the future, and positivity permeates throughout the series’ conflicts. Arguably, it’s even more hopeful than its parent series. The existing reality to which Deep Space Nine is more grounded makes many of its stories feel more pertinent to life as we know it, instead of life we hope it would someday be. Its darker tone only enriches the show’s overall messages about peace and hope throughout its seven season run.