Black Widow’s dark history as a Russian operative and its connections to her decision to die in Avengers: Endgame should be explored in Marvel Cinematic Universe Phase 4 for the sake of Bucky Barnes. The decision to kill Natasha Romanoff during the Vormir leg of the time heist has garnered a divisive response from the public. While the filmmakers repeatedly attempted to explain it, there’s still backlash; Cate Shortland’s Black Widow film is expected to further justify it, but aside from that, it also needs to fully tackle the character’s arc in the MCU, including her checkered past before becoming an Avenger.
Not much is known about Black Widow’s life before she was recruited by Nick Fury to become a SHIELD agent, but there have been bits and pieces of information about it that have been revealed throughout her time in the MCU. For starters, Hawkeye was initially sent to kill her but decided not to, hence why they had a special bond with each other. There’s also the infamous Budapest incident that continues to remain a mystery. Avengers: Age of Ultron further hinted at Nat’s life before the Avengers with teases of her training in the Red Room; this is in conjunction with the supposed red on her ledger that she long wanted to wipe out.
While the ledger has been referenced a few times in the MCU, it has never been fully explored. It’s uncertain if Black Widow will finally tackle this since the movie will delve into Nat’s life outside of being an Earth’s Mightiest Hero. Regardless, it’s imperative for Marvel Studios to do address this important element of Nat’s life, not just to bring her arc full closure, but also for Bucky’s sake. The characters have had very limited interactions in the franchise, but they have quite a few similarities besides their shared connection to Captain America. The most obvious one is that both have a criminal past brought on by exterior factors. Bucky was brainwashed by HYDRA to become the Winter Soldier; meanwhile, Black Widow was trained to be a ruthless Russian spy. If they weren’t saved from their respective predicaments, they could’ve gone on to be unintentional MCU villains. But as they move on from their darker days, they still harbored the guilt about it.
As MCU Phase 4 potentially tackles the red on Nat’s ledger, it could pave the way for how they handle Bucky’s past as the Winter Soldier as well. Resolving this key element in Black Widow’s story in the franchise could be essential in justifying Marvel Studios’ decision to let her sacrifice her life for the greater good in Endgame — something that the Black Widow film tasked to do. There’s an assumption that giving up her life for the sake of the mission was her way of atoning for her past sins and, byway, has wiped out the red marks on her record. But, without knowing what she did to get them in the first place, this particular plot point wouldn’t be effectively resolved.
Similarly, Bucky cannot truly move on from his Winter Soldier days if Marvel Studios do not fully account for what other things he’s done as a HYDRA agent. While the Marvel Cinematic Universe has tackled this quite a bit, there is still a lot that’s unknown about that period in his life. Black Widow’s remark in Captain America: Civil War hinting about a previous encounter proves this. As he embarks on a new adventure and continues his rehabilitation, The Falcon and the Winter Soldier would be the best place to do this. Fortunately for Bucky, however, Marvel Studios still has time to do right by his character unlike Black Widow, whose story has to be retroactively completed.