In the MCU, the Stark legacy has many dark spots:
The Stark lineage has several flaws in the Marvel Cinematic Universe. Howard was a key figure in the formation of SHIELD and the creation of Captain America, eventually working for decades on technological advancement. However, his son Tony pursued a darker path, becoming a lord of war and a weaponeer who bathed in America’s military strength until he saw his creations utilized by the enemy. Now, in Eternals, a crucial revelation indicates Tony wasn’t the first or most lethal Iron Man around. Even before Tony became a hero, Iron Man’s weapons were linked to so much bloodshed, with citizens protesting and the media criticizing. He subsequently rectified himself, but whether it’s robotic suits, bombs, rockets, or anything else, numerous criminals hijacked Stark technology to add to the death tally. Tony, who is identified as Iron Man, had red in his ledger to make up for it.
Eternals’ Phastos was the Iron Man that came centuries before:
Audiences are now learning that the Eternals’ Phastos (Played By Brian Tyree Henry) was the Iron Man from ages ago. This becomes clear when he attempts to build the steam engine in Babylon. Fans watched what Tony accomplished with his equipment, from the holographs to the darkroom, and how his hands were practically shifting pieces in and out of the air. In fact, Phastos may have created the groundwork for the Starks, and like them, he quickly becomes accountable for widespread devastation. So much so that Ajak discovers him in his lab coat, bemoaning how his efforts killed hundreds at Hiroshima, aggravating how he unwittingly became a mass killer. It’s comparable to Tony’s revelation after the war in Afghanistan. As a result, instead of originating from a place of ego like Tony, Phastos’s is so damaged that he runs away from a society he truly wanted to assist. He ends up discreetly utilizing his technical abilities to safeguard his family, resentful at humanity’s use of his expertise to create weapons. It was something Ajak forewarned him about, saying that mankind wasn’t supposed to grow too quickly, which is why he wallows in self-pity and isolates himself.
Phastos’s experiences are quite traumatic as he did more damage with fewer weapons:
After all, whereas Tony’s kill-list was primarily about volume, Phastos delivered far more damage with far fewer weapons. Furthermore, because he’d been alive so long, there were probably a lot more killings involving his inventions that he couldn’t interfere in because Ajak’s regulations wouldn’t allow it. Finally, Eternals watch Phastos breach the laws and develop gauntlets that shoot energy like Tony’s, one that makes a holograph tracing his kin and Tiamut’s volcanic birth, and the bracelets required for the Uni-Mind, which are identical to the ones Tony used to store his nanotech suits. He intends to make amends by banding together with his clan to stop Tiamut from destroying Earth and, finally, by using his tools to atone for the past. Eternals is now in cinemas if you want to watch Phastos’ heritage of death make him the early Iron Man.