“It’s just too dark.”

“It doesn’t feel like Star Trek.”

“Star Trek isn’t about war.”

If you’ve been paying attention to the online discourse around Star Trek: Discovery, you’re probably very familiar with these sentiments. After all, these are a few of the reasons that people have been incessantly criticizing the show, which recently concluded its second season on CBS All Access.

It might surprise you, then, to learn that these criticisms aren’t taken from Twitter comments about Star Trek: Discovery. Instead, they are paraphrased from the Star Trek: Deep Space Nine documentary What We Left Behind, which debuted in theaters and is coming to a television screen near you soon. The show endured very familiar backlash from the “fans.” However, despite the fact that Deep Space Nine wasn’t accepted when it first aired, it appears to be the foundation that the new Star Trek franchise is being built upon.

What We Left Behind is a fan-funded movie that takes a look back at the series, which was controversial at the time it was released. Deep Space Nine was very different than the Star Trek that came before. It was more character-driven, and those characters were often morally ambiguous. It plunged headfirst into the kind of serialized storytelling that wouldn’t become popular for years. It dealt with war, occupation, and its bloody and traumatic aftermath.

Credit: What We Left Behind / Fathom Events

The documentary is a love letter to the series, its actors, its writers, and the fans who stuck by it when it seemed like everyone else loved to hate the show. It’s incredibly well put together and is worth watching for many reasons, from the incredible interviews (Nana Visitor, who played Kira Nerys, one of my personal heroes , is especially a delight), to the jaw-dropping footage that’s been remastered in HD, to the breakdown of what an eighth season might look like 20 years later.

But one of the key takeaways from What We Left Behind, a connection that isn’t explicitly mentioned but is recognizable to anyone who has followed the incessant criticism surrounding Discovery, is that Deep Space Nine is the groundwork on which the current vision of the Star Trek franchise is being built. Without doing that hard, grueling, unforgiving work, the franchise would probably look very different, to its detriment.

Star Trek has never shied away from complex issues — but there’s a difference between confronting difficult, complicated social and moral questions and complex, layered storytelling. I’d argue that Star Trek excelled at the former from the very beginning but the latter didn’t take center stage until Deep Space Nine. While The Next Generation did pick up story threads over the course of the series (the Borg storylines in particular), Deep Space Nine really embraced a long-term narrative with rich character development, against the explicit wishes of the studio.

Now, though, every TV show seems to feature this kind of deep dive into characters and season-long storytelling arcs. In science fiction, this became the norm after Ron Moore’s landmark reboot of Battlestar Galactica. It’s not a coincidence that Moore cut his teeth in the writers' room of Deep Space Nine.

As Star Trek heads into a new beginning, with one hit series airing and four more currently in production (likely with even more to follow), it’s clear that Deep Space Nine has had a lasting and, in some ways outsized, impact on what’s to come. Not only does Discovery’s racially diverse casting take its inspiration from Deep Space Nine (the two series both have Black leads, just to start), but its tone, characters, and the moral ambiguity it confronts are all connected to its predecessor. For example, Starfleet’s covert arm, Section 31, which played a large role in Discovery’s second season and will continue to be important in Michelle Yeoh’s upcoming spin-off, was introduced on Deep Space Nine.

Even the upcoming Jean-Luc Picard series has some of Deep Space Nine’s atmosphere. While the show will, of course, follow in The Next Generation’s footsteps, producers have made it clear that the show will be a bit darker in tone. Stewart specifically said he wasn’t interested in a “jokey” show. He may not be playing the Jean-Luc we remember. From the little we know about the show, it feels like Deep Space Nine.

It’s a great time to be a Star Trek fan. That much is clear. But we all owe the writers, actors, crew, and producers of Deep Space Nine an unpayable debt for doing such good work. For seven years, this team put on one of the best shows in the franchise — I’d argue in television history — and they did it amidst terrible criticism and backlash from the fanbase. They were often ignored, but they used that lack of oversight to produce incredible television week after week. It’s so impactful that you can trace a direct line from Deep Space Nine to Discovery and beyond.

The views and opinions expressed in this article are the author's, and do not necessarily reflect those of SYFY WIRE, SYFY, or NBC Universal.