Captain America’s sidekick, James “Bucky” Barnes is believed KIAed on a mission to thwart Baron Zemo. Unbeknownst to anyone, survives, though wounded and amnesiatic (yay, fake word?) and is revived by Soviet scientists, who replace his severed arm with a bionic one, and keep him in cryogenic stasis when not on missions.
Steve Rogers’ best friend has reemerged as an enhanced brainwashed assassin after being thought killed in action during World War II. That’s gonna make Thanksgiving awkward.