Agents of S.H.I.E.L.D. season 5 has been a fascinating sci-fi action adventure, and has seen the S.H.I.E.L.D. team wrestle with the concept of time-travel in a way that's never really been seen before in a superhero TV show. The gang are desperately attempting to avert a catastrophic future, one in which the Earth was cracked like an eggshell - apparently by one of their own. But their every attempt seems to be failing.

It seems that changing the course of history is no easy task, and events are proceeding exactly as they were meant to be. Fitz and Simmons have married, and Deke unwittingly purchased the ring Simmons was always going to wear; Yo-Yo had her arms sliced off; and Coulson is dying. Everything is happening just as Robin foresaw, and there's a growing sense of impending doom. In the face of this, though, the S.H.I.E.L.D. team seem to be taking a very strange position.

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"We're Invincible"

"Inside Voices" saw three members of the S.H.I.E.L.D. team relax, confident they've become "invincible." Yo-Yo knows she'll make it to the future, and believes she can't be killed. Fitz and Simmons, likewise, have come to realize that the future involves their having a daughter. As a result, these three believe they simply cannot be killed. Simmons went to insane lengths to prove her point, conducting a horrific "test" that involved a glass of hydraulic acid.

Ironically, Fitz is the only one who's actually being consistent. As disclosed in the season 3 episode "Spacetime," Fitz believes time to be fixed. He doesn't buy into the Multiverse theory; rather, in Fitz's view, history has only the one course. Once you've experienced the future in any way, it becomes effectively unchangeable. It's true that season 3 revealed visions of the future can be misinterpreted, but that's not quite the same thing, and it's pretty hard to "misinterpret" the end of the world. So for Fitz, knowledge that he lives on into the future gives him the certainty that he has to survive.

Simmons and Yo-Yo, however, seem blissfully unaware of the logical inconsistencies to their position. "Inside Voices" sees Simmons berate Fitz for suggesting the future is fixed, insisting that there is always hope. She seems blissfully unaware of the contradiction; if the future can actually be changed, then she cannot be "invincible." In fact, Simmons's experiment - and the misfiring gun - offer evidence in favor of Fitz's conclusion; that the Earth is doomed. Simmons and Yo-Yo are actually acting as though their fates are set in stone, even as they insist that future history is not yet written.

What Is The Truth?

There's a sense, though, in which this kind of contradictory position is quite refreshing. Far too many science-fiction and superhero shows give their protagonists an almost instinctive understanding of a franchise's "laws of time." In the case of Agents of S.H.I.E.L.D., none of the team are experts in quantum mechanics and time theory, and they're frankly out of their depth. The truth is that they simply don't know whether or not time can be changed. Fitz is the only one to actually have a theoretical understanding of this at all, and even he can't really comprehend the forces he's dealing with.

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It seems pretty unlikely Marvel Television will choose to destroy the world. The more probably outcome here is that the future is fixed up to a certain point; according to this theory, there are key moments in history - let's call them "junctions" - where a single decision can send all of history down one path or another. This would seamlessly integrate what we've seen in the episodes "Spacetime" and "Inside Voices" with the typical Marvel Multiverse theory; only these key moments have the power to create new futures and alternate realities. The problem facing S.H.I.E.L.D., however, is that they have no way of knowing which decision is the key one that will transform the future. It's best to continue assuming that every decision matters, and that missteps could still be fatal.

Simmons and Yo-Yo have good intentions. But they need to decide whether they believe the future can be changed or not.

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Agents of S.H.I.E.L.D. season 5 continues with "The Honeymoon" Friday April 13 at 9pm on ABC.