Youd be forgiven for writing off Marvels Agents of S.H.I.E.L.D. as a typical freak-of-the-week procedural early in its run. At its launch, its premise was simple: follow the missions of a team of agents from the awkwardly named Strategic Homeland Intervention, Enforcement, and Logistics Division, an intelligence agency with global reach, as they investigate enhanced beings and unusual gadgets. Its formula was familiar, akin to old Syfy staples like Eureka and Warehouse 13. But by the closing episodes of its first season, this premise was blown up along with the eponymous organization, which was dismantled from within by rogue agents and labeled a terrorist group by the U.S. government. And what emerged from the rubble was a fundamentally different show.

Over the course of six seasons, S.H.I.E.L.D. has evolved into a science-fiction fantasia, what one character describes as a fifth-dimensional freak show, exploring human mutation, artificial intelligence, virtual reality, space exploration, time travel, and even magic (a.k.a. unexplained science, as agents Fitz and Simmons would say). In its previous season, it became a full-blown space opera, equipped with aerial shots of spaceship fleets and the gaseous surfaces of distant planets, not to mention two alien species intent on invading Earth. And when S.H.I.E.L.D. returns for its seventh and final season tonight, it will continue to be a different show from the one that premiered in the fall of 2013. Promotional material promises more time travel, more threats of alien colonization, and more life-model decoys, but its too early to determine where this new mission will take the agents geographically, emotionally, or even temporally the season begins in 1930s New York, but the likelihood of it staying there for long is slim. So whether you wandered away from the show during its first year or some time in a subsequent season, now is a good time to revisit how its reconfigured itself over the years.

What makes the evolution of S.H.I.E.L.D created by Joss Whedon, Jed Whedon, and Maurissa Tancharoen intriguing is not merely that it touches on numerous science-fiction tropes or that it has graduated from episodic to more serialized storytelling over the years. Nor is it the fact that it holds the distinction of being the first show to bring the shared universe of the MCU to the small screen and has subsequently outlasted other Marvel projects scattered across Netflix and Disney-owned ABC, Freeform, and Hulu. (Its the last show produced by Marvel Television under Jeph Loeb, the studio having since folded under the Kevin Feigeheaded Marvel Studios.) No, whats most fascinating about S.H.I.E.L.D. as it enters its endgame is how its committed to the practice of essentially adopting a new subgenre every ten or so episodes, particularly later in its run, which breaks its 22-episode seasons into multi-episode arcs. So while much of season one is a spy procedural, the first half of season four is a ghost story. And around the time Dolores Abernathy began questioning the nature of her reality on Westworld, S.H.I.E.L.D. became a robot thriller, with A.I.D.A., a life-model decoy created to protect field agents, searching for a way to achieve her own humanity in the second half of season four. The series bounds from one subgenre to the next at such rapidity that theres barely time to to wrap your mind around one concept before its on to the next, with characters openly decrying the pace at which the team faces new trials and tribulations. But this breakneck speed also means that there are few filler episodes, allowing the show to maintain its momentum within and between seasons.

Thats not to say that there are no periods of downtime, moments in which, usually after the defeat of some megalomaniac, the agents can recline and enjoy each others company. Because for all of its superhuman phenomena, S.H.I.E.L.D. foregrounds human connection and the capacity of humans to do right by each other. The found-family sentiment is as prevalent here as it is on other long-running workplace-based shows if not more so, since the agents live, work, and regularly face their mortality together. This is particularly true of the relationship between Phillip J. Coulson (Clark Gregg), the team patriarch, a man who has given his life to S.H.I.E.L.D. in every sense, and Daisy Johnson (Chloe Bennet), an orphan whos spent her life searching for her family, only to be traumatized by the truth of her origin.

As the best science-fiction dramas tend to do, S.H.I.E.L.D. grounds its fantastic elements with real emotion. And its marriage of the two is so successful that in season five, which features Inhuman fighting pits and insatiable space roaches, its the civil war that erupts within the team that foments the greatest tension. The question of whether to allow Coulson to die, if saving his life could mean the destruction of Earth, seems easy enough to answer: Whats one mans life when the world hangs in the balance? But the agents are so dedicated to each other and to their mission that, for some, it does become a dilemma, yet another hard choice for people used to making hard choices, having already endured years of personal sacrifice to stave off near-annual extinction-level threats.

After scoring two unexpected season renewals (its no coincidence that the season-five finale is called The End), S.H.I.E.L.D. is going out on its own terms with season seven, a coveted planned conclusion in a television landscape rife with sudden cancellations. Fittingly, the show that originally brought the world of the MCU to the small screen will also serve as an outro to the cinematic universes first phase in television, as Marvel Studios ushers in a new phase with a slew of series produced for Disney+, set to begin rolling out later this year. S.H.I.E.L.D.s longevity is no doubt partly due to its penchant for reinvention, its ability to explode the scope of its storytelling season after season. But while the show has come a remarkably long way from its pilot, with the core group of agents now bouncing around the past, the characters ever-deepening devotion to each other has served as an emotional through line, a constant for the characters (and viewers) to hold on to as the narrative rapidly changes around them. And now, with their final adventure about to begin, theres no better time to join the team.

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Agents of S.H.I.E.L.D. Never Stopped Reinventing Itself - Vulture