When Captain America: Civil War was announced, complete with almost the entire cast of The Avengers, people understandably worried about whether or not we'd actually get any resolution to the Cap and Bucky story. You remember, that brilliant plot thread that was at the heart of everything that made The Winter Soldier such a brilliant film? But with Iron Man, Falcon, Black Widow, Black Panther, Spider-Man and the rest tearing up the screen, the concern was that Bucky Barnes' story would be left to fall by the wayside. Thankfully, the trailer that arrived late last month dutifully put minds at rest, placing Cap's fight to protect his best friend from his fellow Avengers front and centre. All of which is great, obviously, but just what sort of role will Barnes' and his metal arm play in the civil war? After all, he's not present in Mark Millar's original comic book. Can Bucky be trusted? Does he want to return to a normal life? Does he need to oil that arm so it doesn't squeak on stealth missions? All these questions and more require intense and wild speculation from now until the UK release date of April 29th. For now though, lets look at some possibilities on how Bucky will be key to Civil War. Beware though, potential spoilers lay ahead, especially if the MCU follows the path of the source material.