The newly-released Art of Avengers: Endgame has revealed new details about the development, plot and design of Avengers: Endgame and the MCU's other most ambitious projects. The book is bursting with fun facts and behind-the-scenes looks, including a first look at an infant Thanos.
While the book is primarily focused on Endgame, it contains a lot of material from previous movies as well. The photos of a very young Thanos come from the "Unused Concepts" section that includes much of the concept art and ideas behind Avengers: Infinity War. Since the two films were originally planned as two "parts" of the same movie, it's not hard to see why Marvel waited until now to release such photos.
Vice President of Development and Creative Director for Marvel Studios, Ryan Meinerding, provided valuable context for the photos. "There was a period of time when they were writing these scripts where you were going to see Thanos' backstory," he explained. However, that part of Thanos' story didn't make it into either of the Avengers' films.
Meinerding described that at one stage in the script's development, Infinity War delved way back into Thanos' background to the time of his infancy. Malformed from birth, the scrapped plotd epicted Thanos growing up as an outcast throughout the stages of his life, at one point "having an actual teen moment of being that seven-foot tall awkward teenager." From there Thanos' journey would more directly depict what he described in the film itself, trying to convince his planet of the dangers of overpopulation as they dismissed him as a mad man and imprisoned him on a nearby moon.
From his vantage on the nearby moon, Thanos would have watched his planet fall into ruins at the hands of the very threat he would dedicate the rest of his life to combating. The concept art of Thanos' growth through the various stage of his lives built backwards from the films' primary Thanos design.
In the theatrical cut of the film that was ultimately released to the public, much of that backstory was condensed to just a few lines of dialogue.While this choice was a fairly elegant, efficient way to cut down a movie that was ultimately criticized for its length, it also kept these fascinating desings from being seen by moviegoers. Seeing Marvel's biggest villain grow up as a ridiculed outcast could have gone a long way to making him more sympathetic, and the character could've been richer and more textured than he was without it.
While a baby Thanos has appeared in comics like Cosmic Ghost Rider, The photo of the infant Thanos also adds some weight to War Machines' musings about traveling back in time to kill Thanos in his crib. While that idea is fairly monstrous at face value, these images offer a tangible reminder of what the Avenger was willing to do to stop the adult Thanos from wiping out half of the Marvel Universe.
In comics, Thanos is one of the Deviants, an ancient alien race. Since the Deviants are traditionally associated with the Eternals, there's a very real chance that these designs could find their way in the Marvel Cinematic Universe in that group's upcoming film.