Phastos is the inventor of the community of genetically-engineered Eternals. Created by the Celestials in the World Forge, Phastos was sent to Earth in 5,000 BC to progress the planet's societal development, and protect it from the Deviants. Phastos guided and progressed many technological innovations throughout the course of human history, but fell into a state of dejection after the atomic bomb was dropped on Hiroshima, which resulted in monumental loss of human life. Blaming himself, he grew distant from his fellow Eternals and abandoned helping humankind. In the contemporary era, Phastos settled and started a family with his husband Ben Stoss, and together raised a son, Jack. When Earth's Eternals reassembled to stave off a new wave of Deviants led by Kro, Phastos came to the realization of his true purpose; to pave the way for Earth's Emergence, which would lead to the birth of Tiamut the Communicator and result in the planet's destruction. The Eternals became divided, with Phastos siding to protect the planet and avert the Emergence from happening. By choosing to save the planet and humanity rather than allow the Emergence to happen, Phastos was abducted from Earth by Arishem the Judge to parts unknown.