Over the course of 12 films, no relationship in the Marvel Cinematic Universe has lit up the internet quite like the one between Steve Rogers (Chris Evans) and Bucky Barnes (Sebastian Stan). The two started out as best friends in 2011's Captain America: The First Avenger, with Bucky looking after the skinny, sickly Steve; and then Steve, transformed into the strong, stalwart Captain America, rescued Bucky during World War II. Their bond seemingly ended in tragedy when Steve witnessed Bucky fall from a speeding train while on an anti-Hydra mission, but it wasn't until 2014's Captain America: The Winter Soldier — when Steve learned that Bucky was instead captured by Hydra and brainwashed into a lethal assassin called The Winter Soldier — that "Stucky" truly became a Tumblr-melting, slash-fiction-launching phenomenon.
Their powerful, steadfast relationship is now the catalyst that drives the central conflict in Marvel Studios' latest movie, Captain America: Civil War: Steve's loyalty to Bucky — whose crimes as the Winter Solider have made him an international fugitive — drives a wedge between Steve and his fellow Avenger Tony Stark (Robert Downey Jr.). The seeds of that arc, however, started way back in the editing rooms for The Winter Soldier, where directors Anthony and Joe Russo first began to grasp the impression Bucky and Cap’s relationship was having on a rather specific audience.
"It was very noticeable to us that the women involved in postproduction were mad for Bucky and the relationship [with Cap]," Anthony Russo told BuzzFeed News in late April in an interview alongside his brother and fellow director Joe. Test screenings with friends and family of Marvel Studios and Disney employees only further reinforced that reaction, and once The Winter Soldier opened in theaters to some of the strongest reviews to date for Marvel Studios, the internet confirmed it.
In the 2000s, the Russo brothers established themselves directing episodes of Arrested Development and Community, where they learned to appreciate the internet as a formidable guide for their creative decision making. "There was a website called Television Without Pity, where there was a very sophisticated group of TV watchers who were like a real-time test audience responding to the content as it aired," Joe Russo said. "We've often used that to our advantage." So they were especially attuned to how "Stucky" had taken on a life of its own online, especially among those who saw their connection through a romantic and sexual lens.
"There's a profound emotionality to the relationship that allows for interpretation, and we're wide open to interpretation to that relationship," Joe said, choosing his words carefully. "It has created a very big, uh, um, you know, shipping component."
The Russos, however, see the kinship between Cap and Bucky as familial. "We're family. We're brother filmmakers," said Joe. "[It's] the concept of Bucky as his brother — two guys who were raised together and had nobody else other than each other, in very poor conditions, and then suffered through the war together."
As the duo worked with screenwriters Christopher Markus and Stephen McFeely through 2014 to develop Civil War, the third Captain America movie, they kept returning to that profound connection between Bucky and Steve — as surrogate brothers, and as war veterans.
"The idea of wanting to save someone who is basically the longest-suffering POW in history is a very emotional concept," said Joe. "So we knew that if we needed a real emotionality in Civil War, the place to go for that would be Cap and Bucky."
Another strong vein of internet Bucky-Cap fandom stands firm in the conviction that Bucky is an innocent, and that passionately — sometimes angrily — opposes the argument that his actions as the Winter Soldier make him a villain. That conflict also proved to be fertile ground for Civil War's filmmakers. "There's a part of [Bucky's] personality that has a lot of blood on his hands, without question," said Joe. "That in essence is what Civil War is about: Is he innocent, or is he not innocent? Is he Bucky Barnes? Is he the Winter Soldier? Or is he something in between? And if he's a thing in between, can he be held culpable for the crimes of the Winter Soldier, or is there a human being who exists in there who is not responsible for anything he did under Hydra's control?"
For Cap — and for Stucky fans across the internet — those questions have been answered. "Cap's devoted to the idea that there is still a human being inside the Winter Soldier that he knows and loves," said Anthony. "And he's going to find that human being in there, no matter what it costs him. It's just an amazing relationship."