Eternals
The Eternals are a race of proto-humans bred by the Celestials for longevity and superhuman powers.
As a direct result of Celestial engineering, baseline Eternals are at the apotheosis of human evolution. Universally they are nearly immortal and functionally indestructible. Every Eternal has superhuman strength, telepathic capability, and immense physical durability.
With the augmentation of cosmic energy thanks to the experimentation of their leader Kronos, Eternals manifested a much wider array of powers. Eternals use the Power Cosmic to channel energy into themselves, creating the ability to fly, transmute matter, and to discharge or absorb energy.
History
The first colony of the Eternals was located on Earth, some 5,000,000 years ago. The first Eternals were named Kronus and his brother, Ouranous. A civil war broke out and Ouranous' faction was expelled. They found a Kree outpost on the planet Uranus and conquered it, ca. ~750,000 BCE.
The Kree counterattack forced down an Eternal colony ship onto Saturn's moon of Titan shortly thereafter. A new Eternals colony was established, called Titanos. It is from this colony that the divergent Eternal, Thanos rose. A powerful Deviant Eternal, Thanos was exiled for high crimes and murder. He returned at the head of an army, and left only one hundred of the Eternals alive before being routed and forced to flee.
Approximately 47,000 BCE, a Kree science colony ship captured an Eternal observing humans. The Kree were able to derive much genetic information, leading to the development of the Terrigen Mists.
In 42,000 BCE, the Demiurge flared to life. As a result, Kronos became able to channel the Power Cosmic. However, he also became an immaterial entity. His sons Zuras and A'lars founded two new cities: Zuras, founding Polaria (in the Antarctic) and A'lars resettling the colony of Titanos with his wife, Sui-San.
Eternals assisted in the defense of the Demiurge against the Celestial invasion during Ragnarok, but faded from view after abandoning their home on Earth. Eternals live exclusively on the colony of Titanos.
