SPOILERS for Agents of S.H.I.E.L.D. and Avengers: Infinity War ahead.
The latest episode of Agents of S.H.I.E.L.D. season 5, "The One Who Will Save Us All," revealed Avengers: Infinity War villain Thanos is the real threat against Earth this season. All season, Phil Coulson and his team have been searching for a way to prevent the Earth's destruction. However, since they didn't know for sure how it was destroyed, they've struggled to come up with a plan to save it. Plus, what with Hydra, Gravitonium, the alien Confederacy, and Coulson's imminent death, a lot has been working against the agents.
Further, after the release of Marvel Studios' latest last week, the ending of Avengers: Infinity War indicated there will be major changes to S.H.I.E.L.D. if they can survive their own impending apocalypse. However, as of last week's episode of Agents of S.H.I.E.L.D., which featured a small reference to Infinity War, it was unclear whether the two Marvel properties would tie together more. Season 5 supporting actor Adrian Pasdar did preview more Infinity War connections, and this week's episode certainly delivered. In fact, thanks to the revelations of "The One Who Will Save Us All," we now know Thanos is indirectly responsible for the main conflict of season 5.
In an earlier season 5 episode, "Rise and Shine," we learned that Hydra had made a deal with the Confederacy for protection from an impending alien attack in exchange for Inhumans and Gravitonium. Though the vision Qovas gave Coulson of Thanos' ship teased the Mad Titan was responsible for the attack, it wasn't until this week's episode that it was confirmed. Talbot, who became the Destroyer of Worlds (and the Marvel Comics villain Graviton) last week, meets with the Confederacy and learns of Thanos' attack from the Kree warrior Taryan. The key part of their exchange is as follows:
Taryan: Thanos, and his forces, have begun an assault on your world even as we speak.
Talbot: Well then, I’ve got to get down there with the Avengers and take on this Thanos.
Taryan: Thanos’ strength is unrivaled you will lose even with your powerful friends fighting alongside you. Though perhaps there might still be a way.
Taryan convinces Talbot to search for more Gravitonium in order to give himself more power, hinting at how Graviton could destroy Earth and keep the time loop in tact. Though we don't know exactly what will happen in the final two episodes of Agents of S.H.I.E.L.D. season 5, Graviton wanting more power in order to take on Thanos seems to be a key step toward Earth's destruction. Plus, since the Confederacy used their foreknowledge of Thanos' attack to extort resources from Earth and inspire Hale to revive Hydra's Destroyer of Worlds project, it stands to reason the Mad Titan is the true villain of Agents of S.H.I.E.L.D. season 5.
Of course, we know that Graviton never takes on Thanos in the Marvel Cinematic Universe, since the Mad Titan doesn't actually set foot on Earth until the end of the Battle of Wakanda. (The timeline of exactly how Infinity War fits into Agents of S.H.I.E.L.D. is murky, but it's likely that battle hasn't started yet in the show's continuity.) However, we can trace the main conflict of season 5 back to Thanos. His impending attack is used to set events in motion that lead to the destruction of the Earth. Not to mention, his imminent arrival in "The One Who Will Save Us All" incites Graviton's thirst for power.
Whether or not Graviton is truly the one to crack the Earth apart in his quest for more Gravitonium, Thanos is still the ultimate villain of Agents of S.H.I.E.L.D.'s latest season. Considering how massive of an event Avengers: Infinity War proved to be - both within the MCU and the real world - it makes sense for the Marvel TV series to tie into the film more closely than previous Marvel Studios releases. What that means for the remaining episodes of Agents of S.H.I.E.L.D. season 5 and what happens to the team after Thanos snaps his fingers, though, and remains to be seen.
Agents of S.H.I.E.L.D. season 5 continues with "The Force of Gravity" Friday May 11 at 9pm ET on ABC.