Warning! This article contains spoilers for Eternals! Read at your own risk!
As Thena was slowly fading away with Mad Wy’ry, a dementia-like disease that makes her feel lost in her memories as she starts attacking the other members of the Eternals, she repeatedly mentions Centauri-6 and the reason why lies behind the truth in their existence.
Eternals: What Happened in Centauri-6?
Thena, bearing the name of “the Defender” in the team, Thena is always off to righteous missions. She possesses immortality, flight, strength, speed, teleportation, shooting heat rays, and channeling of cosmic energy. In short, she is the best warrior the team has. She is often called by the others as the Goddess of War.
Unfortunately, in the movie, she is experiencing Mad Wy’wy, a dementia-like disease that affects her memories. When afflicted, she gets episodes of violence where she goes on full rage to everyone around her and she is, as if, on an instant kill mode. She keeps mentioning that it is too late for the others and starts attacking them.
This caused her a semi-banishment and with Gilgamesh, she stayed in the deserts, in seclusion where she cannot hurt anyone but Gilgamesh who is strong enough to counter her attacks and he found a way for her to remember who she is and have something that she could vent out her episodes.
Thena draws tons of things that are resembling that of Celestials. Sersi saw it. When Thena got into an episode, she started attacking the Eternals again and she kept mentioning “Centauri-6” which made the others wonder what she is talking about.
When Sersi finally knew how to connect with Arishem, the Prime Celestial talked to the Prime Eternal about the truth of their existence. It turns out that the Eternals are built to ensure that the birth of a Celestial planted like a seedling on a planet against the mistake he made, the Deviants. They were robot-like constructs and their memories are wiped every after mission or Emergence that happens.
As for Thena, her memory wipe must have been problematic or glitched that her programming must have failed wiping it all and the Mad Wy’ry gives her flashbacks of her life before Earth. It turns out, Centauri-6 is one of the planets destroyed for the birth of a Celestial and they were there when that happened.
See Thena and her amazing skills in Eternals, now in theaters.