Eternals reveal why they didn’t intervene in Avengers: Infinity War to stop Thanos’ Snap. However, the explanation given creates a new MCU plot hole. One of the biggest mysteries surrounding Eternals has been where the characters were during Infinity War and Endgame events. Having been on Earth for 7000 years, the Eternals were in a position to stop the Mad Titan from destroying half of the universe, but they remained idly by.
To begin with, Eternals offer a logical explanation for their lack of involvement. They were only told to intervene in Deviants’ situation when they arrived on Earth from the Celestials. It makes sense that the Eternals didn’t intervene in Infinity War because the Deviants were wiped out centuries before the main events in the MCU’s timeline, including Thanos’ Snap. This is only part of the answer, and Marvel raises new questions as a result.
A later scene reveals what happened in the movie. The Eternals were secretly paving the way for the Emergence, allowing Celestial Tiamut to rise to power on Earth. If war were necessary for human evolution, then technological advancement and population growth would have been possible without it. Following this, the Emergence would have occurred. As a result of Thanos’ Snap, the Emergence’s proper explanation for not interfering becomes an MCU plot hole. This is because he planned to wipe out half of life in the universe, including on Earth.
Because the threat of Thanos posed to the fundamental goal of Celestial, Ajak was still pretending to the other Eternals that they weren’t interfering without Deviants. However, it doesn’t make much sense for them to be instructed to get involved. The Deviant told Ajak and the team to stop “balance” because Arishem knew about Thanos’ quest for the Infinity Stones. This was a cover story.
This is why Arishem should have known that it would be an enormous setback for the Mad Titan. Naturally, how the rest of the team is convinced would depend on whether Ajak tells the truth. This could cause some division similar to that seen in Eternals, or if they try to pretend that Thanos is a Deviant. Even if neither option has its flaws, at the very least, Arishem would have had some Eternals fighting against Thanos. It is important to remember that the team was already divided.
In addition, the film does not take into account Thanos’ Eternal past. Thanos, like his brother Starfox, is a confirmed Eternal in the comics. In one of the post-credits scenes from Eternals, Harry Styles appears as Eternal, indicating that Thanos, too, was an Eternal in the Marvel Cinematic Universe. A further mystery is raised if Thanos is an Eternal, In this case, the team might have been justified in intervening.
This is because it is the Eternals’ business. Ultimately, not interfering worked out for the Eternals, if not in a good way. The Snap and Blip caused an enormous wave of energy and a surge in the populace when they came back. This further helped the Emergence get started. However, why the Eternals skipped Infinity War remains unanswered without knowing whether Arishem had the foresight for that.