One of the first major questions to follow in the wake of the Eternals trailer was the whereabouts of these all-powerful cosmic beings during the entirety of the Infinity Saga, when Thanos slowly but surely assembled the stones to erase half of all life with one click of his fingers.
Obviously, the answer is because the movie wasn’t in active development until right around the time that Avengers: Endgame had almost finished shooting, but fans demand the Marvel Cinematic Universe answer almost every question with an in-canon explanation, which it looks like we’ll be getting after the first synopsis teased a direct connection to Endgame.
However, a new theory puts forwards the idea that the reason why the titular team hasn’t interfered in the MCU up until they got their own film is directly tied to Captain America, and it makes a surprisingly solid amount of sense. Multiple Easter Eggs referencing Steve Rogers were spotted in the first footage, and he was directly mentioned by name, but the connections could run much deeper.
As per the theory, it’s been established that the Eternals have gently nudged humanity in the direction of scientific and technological advancement, so as the inventor of the group, Brian Tyree Henry’s Phastos may have pointed the human race towards things like the discovery of vibranium and the missing pieces of the puzzle required to crack the super soldier serum, both of which are integral to Captain America’s creation.
Not only that, but giving the world a superpowered being consumed entirely by the desire to do the right thing would make Cap a cipher of sorts for the Eternals, leaving them to continue watching Earth from the outside looking in, especially when cosmic threats made themselves known and the Avengers were formed to combat them. In any case, the demise of Captain America and Iron Man removes the planet’s top physical and technological specimens from the equation, and that could serve as the catalyst for the immortal aliens to step out of the shadows.