Eternals writers Kaz and Ryan Firpo had a huge task in front of them as they began to crack the story of Eternals. Telling the story of the very origins of the Marvel Cinematic Universe, reinventing some very obscure characters for the film and deciding what themes to include were just some of the big jobs they had to handle and they had to pack it all into a huge, sci-fi epic. Inverse got to talk to the writers and, according to Kaz, despite the film featuring all manner of Cosmic being, including the massive Celestials, the pair looked at the film as an opportunity to get philosophical about humanity itself:
Eternals is using the lens of science fiction to ask big questions about purpose and responsibility and love. Stories provide us an opportunity to ask big questions. If you come from a movie with a big question you’re still grappling with, that’s a great success. Because we’ve gotten you to think about what it means to be human for just a little bit.
In prepping to take those big questions to the big screen, the writers first dove in to the comic book history of the characters. While the bulk of their stories were told through creator Jack Kirby’s original run and Neil Gaiman’s modern run, another lesser known run also had a big influence on the film: 1999’s Earth X. Earth X was written by Jim Kreuger who worked with Alex Ross (who originally created the dystopian future seen in the series) to put together a 14-issue run that took a look at a world where most everyone had super powers and, pertinent to Eternals, had a Celestial growing at its core! Kaz described the process of digging into the comic book history of the characters and how Earth X stood out for the way it took on the sort of big, philosophical ideas they wanted to tackle:
The process began with Marvel handing us a 700-page PDF that had everything, every time the Eternals had appeared, even in Avengers [comics]. We read all of it. Comics are an incredible medium because they’re about different artists having different conversations in the shared universe. Comics inherently are about the multiverse; it’s different takes on these same stories. For us, it became [about] bringing our own story to the lineage. Earth X was an uncanny bible that sat around in the writer’s room because it tackled huge ideas.
Ryan also indicated that while the Kirby and Gaiman runs each lent part of their stories to the DNA of the film, it was the philosophy of Ross’s Earth X idea that caught their attention. The use of Earth X as a “bible” for the film goes to show how valuable any corner of Marvel Comics vast library can be as creators begin the process of adapting these stories and characters for the MCU. The stories begun in Earth X have continued to grow through the subsequent series Universe X, Paradise X and Marvels X; maybe those series will become the bibles for Eternals sequels or for other projects down the road.