Warning! Spoilers ahead for Marvel's What If...? episode 3, "What If...The World Lost Its Mightiest Heroes?"
Thanks to Marvel's What If...?, the MCU just made Bucky Barnes' Winter Solider story even darker than it already was. Featuring an alternate timeline where nearly all the Avengers were murdered before they could ever assemble, Marvel's What If...? episode 3 features a line from Samuel L Jackson's Nick Fury that implies the Winter Solider's involvement (despite not being featured directly in the episode). While Bucky wasn't the assassin who killed Earth's Mightiest Heroes himself, it seems likely that a past murder by Hydra's brainwashed assassin created the domino effect that led to their collective demise.
In Marvel's What If...? episode 3, Jefferey Wright's The Watcher reveals an alternate MCU that's much darker than the primary universe. Taking place during "Fury's Big Week" (the week in which all occur), the Avengers start dropping one by one, being killed by a mysterious unknown assailant. However, Fury eventually puts the pieces together and faces a dark and vengeful Hank Pym wearing his own Yellowjacket suit. Apparently, Pym's daughter Hope van Dyne became a SHIELD agent in this universe (taking after her mother Janet) but was killed on a mission. As payback, Pym sought revenge by killing Fury's potential candidates for the Avengers Initiative (Iron Man, Black Widow, Hulk, and Hawkeye), as well as those who Fury might have recruited along the way (like Thor).
However, a critical line from Fury reveals that Hope's death happened on a mission in Odessa, Ukraine, which is actually a pretty big Easter egg. In 2014's the hands of the Hydra's Winter Soldier, motivating Hank's revenge quest in killing all the Avengers and making Winter Soldier's legacy so much darker by making him the primary catalyst.
Had it not been for the Winter Soldier killing Hope, the Avengers might have still survived to assemble later on in this new timeline rather than putting the world at risk with their absence. Despite Hank Pym being defeated and arrested, the world was left largely defenseless without its heroes, something Asgard's new King Loki and his armies took advantage of by immediately invading. While this resulted in Fury searching for new heroes to keep the Avengers idea alive (discovering a still-frozen Captain America and paging Captain Marvel), it looks as though the Winter Soldier himself played a secret role in the deaths of so many heroes during this alternate retelling of the MCU's Phase 1.
In any case, while the MCU story for the Winter Soldier is so much darker in Marvel's What If...?, it's thankfully set in this alternate timeline devoid of any major consequence (for the time being). The Winter Soldier can still have his redemption arc from Falcon & The Winter Soldier where he seeks to make amends and make up for his past sins as a free Bucky Barnes, something that would be extremely hard to do had he actually killed almost all the Avengers during Marvel's Phase 1 as Hydra's assassin.
Marvel's What If...? releases new episodes Wednesdays on Disney+.
