The Marvel Cinematic Universe has introduced more than a few successful subjects of the same experiments that turned scrawny Steve Rogers into Captain America, but the rest of the characters to have survived the process haven’t experienced the same sort of results, to put it lightly.
The Incredible Hulk brought the serum into the MCU years before The First Avenger was released, with Emil Blonsky taking a turn for the worst and ending up as the monstrous Abomination. Bucky Barnes, meanwhile, was brainwashed into becoming infamous assassin the Winter Soldier and the Red Skull was hellbent on ruling the world, while The Falcon and the Winter Soldier revealed that Isiah Bradley had been locked up for decades.
That’s hardly encouraging data, but a new theory puts forward the idea that John Walker could end up receiving the super soldier serum to officially cement his position as the new Captain America, which will ultimately only continue his journey down a dark path. He’s got the costume and he knows how to throw the shield, but Walker is still just a regular guy at the end of the day, one who may become increasingly desperate to live up to his predecessor’s legacy.
The Power Broker was name-dropped in the most recent episode, and in the comic books, he’s known for turning regular people into superheroes. And when you factor in Walker’s own history in the pages of Marvel Comics for being a more reckless and dangerous Captain America, then it seems like a logical progression for The Falcon and the Winter Soldier to mimic that arc and use the serum as a method to establish him as an entirely new and potentially a lot more evil version of the star-spangled crimefighter.