Warning: Minor spoilers ahead for Eternals.
Thanos' origin story is deeply connected to the Avengers: Endgame, the future of the MCU seems read to explore more of his connections and history.
Based on characters created by the legendary Marvel Comics writer and artist Jack Kirby, Eternals tells the story of a group of ancient immortals who have lived on Earth for thousands of years. All this time, this mysterious race of super-powered beings have managed to keep their existence a secret from mankind. In the movie, the Eternals embark on a mission given to them by their creators - the Celestials - to battle the Deviants, who in the comics are their greatest enemies, and protect Earth. The cosmic epic will introduce audiences to at least ten of their race, including Ikaris (Richard Madden), Ajak (Salma Hayek), Sersi (Gemma Chan), Thena (Angelina Jolie), and more.
Eternals is expected to delve into the history of the MCU by featuring scenes that take place over a thousand years ago. Places like Babylon will be making an appearance. Other eras, including the Amazon and Mesopotamia, also make appearances in the film. While Thanos' backstory could have been expanded upon in the movie, the story made a smart decision by avoiding Thanos' history altogether, only introducing Eros, Thanos' (seemingly younger) brother who pitches in to help the Eternals in the mid-credits scene. Thanos might be long gone, but the MCU seems interested in exploring his relatives, tying Eros to the other Eternals and having them band together, which is something the shared universe of films haven't done before. Previously, Thanos has only operated on a solo basis, but Eros at least seems like more of a team player, though not much is known about him beyond the fact that he has some charisma.
But what exactly is the connection between Thanos and the Eternals? He doesn't look like them. Here's what you need to know about the relationship between this ancient race of immortals and the Mad Titan.
Thanos And The Eternals' Backstory Explained
The Eternals were created thousands of years ago by the god-like Celestials. After visiting Earth and experimenting with human DNA, the Celestials created two off-shoots of humanity, the Eternals and the Deviants. The Eternals resemble humans but are gifted with immortality; the Deviants, on the other hand, were a colossal failure. They have unstable DNA, and are monstrous in appearance. They also don't share the immortality of Eternals. Since they couldn't blend in with humans, they constructed subterranean cities for themselves and went into hiding.
The Eternals ultimately established a base on Earth. Later, the leader of the Eternals, Kronos, conducted an experiment with cosmic energy, but it went wrong, and the spread of the energy altered the genes of the Eternals permanently. For this reason, the Eternals and all their descendants possess a wide array of superpowers. So their race survived the accident, but Kronos was no longer in any condition to lead. Since his two sons, A'lars and Zuras, couldn't agree on who should be his successor, they decided to split the Eternals into two branches. Zuras founded a new city and became the leader of the Olympian Eternals, while A'lars left Earth and took a large number of the Eternals with him. A'lars traveled to Saturn's moon, Titan, and started a new colony there. His gathering of Eternals became known as the Titanian Eternals.
While on Titan, A'lars fathered a son named Thanos with an Eternal woman named Sui-San. Sui-San was actually on Titan at the time of the cosmic event on Earth that gave the Eternals their powers, which means that Thanos doesn't have the same set of powers shared by Ikaris and all the others. Only his father benefited from the effects of the experiment. Interestingly, Thanos is related by blood to Thena, since she's Zuras' daughter; that means the two characters are actually first cousins. Despite this connection, Thanos has little to do with the Olympian Eternals, and has had limited interaction with them in the comics.
Why Thanos Looks Different To The Other Eternals
Like the Earth-based Eternals, the Titanians look just like humans. This includes A'lars, Sui-San, and Thanos' brother, Eros (aka Starfox). So why does Thanos look different to everyone else in his family, not to mention his entire race? That's because Thanos was born with the Deviant Syndrome, making Thanos a genetic rarity among his people. Due to this strange mutation in Thanos's DNA, Thanos has heightened abilities and bears some physical similarities to the Deviants (but is still an Eternal). It's possible there are other Eternals in the Marvel Universe who have the Deviant Syndrome, but Thanos is the only character confirmed to possess it. With Eternals' introduction of Eros and the titular heroes going on a mission to find other Eternals, it's possible the MCU will introduce another of their species who is similar to Thanos in DNA.
Thanos Could Be An Eternal In The MCU
With all this in mind, the question arises, is Thanos an Eternal in the MCU - a full-fledged one, that is? The answer to that question was unclear, but with the introduction of Eros, the answer seems far more concrete. After all, Eros knew who the Eternals were, who they were waiting to hear from, and where to find them. That suggests he knows a lot about Arishem and the Celestial mission, which therefore implies he and his brother were both Eternals. The existence of the characters and the film itself means the MCU can delve into the history of the other Eternals and Thanos (through Eros). Plus, nothing revealed about Thanos in Avengers: Infinity War and Avengers: Endgame proved that Thanos wasn't an Eternal, so it does seem possible that he could be one of them; it just hasn't been explored yet.
Avengers: Infinity War revealed that Thanos' people, the Titans, became extinct because of an unspecified catastrophe. They were spotted briefly in the movie, but they were too far away to get a proper look at them. It was stated by Infinity War VFX supervisor Matt Aitkin that if the movie had shown more of Thanos' race, audiences would have noticed that the other Titans didn't look like Thanos. They wouldn't have had his bright purple skin color, trademark chin, or his towering height. The plan was to present Thanos as a "little bit of a mutant of his own people". This certainly sounds like his Deviant Syndrome from the comics.
With this in mind, it makes sense that the MCU's Thanos could be an Eternal with the Deviant gene. This would explain why he doesn't look like the characters from Marvel's Eternals film or his brother. Marvel's Eternals movie didn't have a chance to establish Thanos as an Eternal. Infinity War already mentioned his father, A'lars, through a reference from Red Skull (Ross Marquand), and the next few MCU movies could follow up on that when it explains more on the Eternals of other planets.
