The Agents Of S.H.I.E.L.D. Decimation Theory That Has Fans Groaning
Over its 12 years of dominating pop culture, the Marvel Cinematic Universe became a unique — and highly successful — force at both the box office and on television. Both of these mediums, not to mention books and comics, intersect at various points to tell a more complete account of the MCU's biggest stories. Agents of S.H.I.E.L.D. withstood as one of the strongest pieces of Marvel media, in this regard, fleshing out plot points that couldn't receive proper attention on the big screen otherwise. Even though Its canon status began to erode toward the end of its run, many still feel it deserves a spot in the MCU timeline.
It's no secret that Agents of S.H.I.E.L.D. started to deviate from the franchise around season 5, rarely dealing with what was going on in the films and instead focusing on its own, more grounded adventures. With that being said, it did make a brief note of the Infinity Saga's biggest moment, that being Thanos' (Josh Brolin) Decimation, or "the snap" ... however, much to the surprise of viewers, the event that killed off half of all life in the universe somehow played no serious role in AoS' narrative.
The reason for this stems from the secrecy surrounding Avengers: Infinity War, leaving Marvel's television writers in the dark as to where the MCU was going to avoid spoilers. Therefore, they had no choice but to move the series along as if the Decimation didn't happen — adding fuel to the speculative fire that AoS is its own entity. Even still, there is a workaround to this discrepancy, as detailed by a fan theory posted on Reddit, but, it wound up leaving the majority of readers unimpressed.
Loki taking the Tesseract puts Agents of S.H.I.E.L.D. in a different timeline
Reddit user revilo1000 put forth this theory in an attempt to make sense of why the Decimation wasn't a big deal on Agents of S.H.I.E.L.D.'s later seasons, claiming that the entire show takes place in a separate continuity from the rest of the MCU. In fact, according to them, "the whole of Agents of SHIELD happens in the universe where Loki disappeared with the Tesseract." This might seem a bit crazy on paper, but it makes a lot of sense taking into account the MCU's rules on the multiverse.
For those who don't recall, in Avengers: Endgame, the titular team traveled throughout time to collect the infinity stones to undo Thanos' destruction. This led them back to 2012 for the Tesseract, or, the Space Stone, but their attempt to secure it proved unsuccessful. As a raging Hulk (Mark Ruffalo) inadvertently knocked the Cosmic Cube loose from its casing, the previously captured Loki (Tom Hiddleston) made off with it, disappearing into the cosmos and thus establishing a branching timeline (as well as a new Disney+ series for himself).
revilo1000 elaborates on their theory, breaking down why Infinity War, Thor: The Dark World, and Thor: Ragnarok stand out as the most drastically changed MCU films in this new continuity. First off, in this version of Infinity War, "Thanos launches his mission to collect the stones, but falls one short and can never snap because something happened with Loki and the Tesseract. Which is why we see Thanos mentioned in Season 5 of SHIELD, but never see any of the fallout or mention of the snap."
Continuing their speculation, as far as The Dark World goes, "The events of The Dark World could play out differently based on Loki's lack of involvement, but I don't think it's too much of a stretch to say the minor damage the Agents of Shield team investigates in Season 1 remains the same in this timeline." As for Ragnarok, they imply the changes wouldn't be major since "the events of Ragnarok don't affect the show so it's safe to assume any changes from the MCU timeline we know would go unnoticed on SHIELD."
Fans were less than eager to embrace this concept
Despite this theory being pretty thorough and making just enough sense to work, the Agents of S.H.I.E.L.D. fans on Reddit made sure to voice their disagreements with it. User FrostyPig23 countered with a very blunt response, saying the Decimation "didn't happen because it wouldn't have added anything of value to the show," since the team was largely powerless to do anything about it. "The Avengers solve the problem, so it would be meaningless to include in the show."
Another Redditor, Agent-Krazminski, chimed in with their two cents on the matter, explaining that "the snap works out magically to preserve the OG avengers while killing almost all the rest of the superheroes FOR THE SAKE OF THE PLOT.... It's a little mind boggling to me how so many Agents of Shield fans won't give it the plot leniency that the movies take for granted." They bring about a great point, looking beyond the universe itself and taking on a reality-based perspective, citing that the Decimation didn't play a role in AoS because it would've only complicated the program. It proved best to leave it alone for the sake of the plot.
While many were critical of this theory, a handful of others voiced their support for it by taking the ideas it presents to another level. "I think there can be infinite alternate timelines that vary very little from one another," claimed user Arkthus, building off of revilo1000's initial post. They also presented the idea that perhaps AoS did, for a time, exist in the MCU timeline, before splitting off, thus justifying its abandonment of following the movies' stories. "season 1-4 => MCU timeline, end season 5 to season 7 => alternate timeline created by Loki's departure."
Obviously this theory isn't set in stone, and no one has to adhere to it as if it came from Kevin Feige himself. That's the fun of making up fan theories: You can conjure up anything you'd like, just for the sake of argument. This particular one might not be perfect, and Reddit's users certainly looked it over with a fine-toothed comb, but it would certainly go a long way in reasserting Agents of S.H.I.E.L.D. as a vital piece of the MCU puzzle.