“We weren't going back to World War II. Cap cannot travel in time. So while Tony can go home to Malibu and Thor goes up to Asgard and Hulk can sort of ride the rails, Cap was stuck. So Cap does stay with S.H.I.E.L.D. because he has nowhere else to go. But he's not necessarily comfortable there. And just as he's given permission to let go of the past and to focus on the modern world, a ghost comes up. With the Greatest Generation in World World II, there's a tendency to reflect on that period and say, 'Things were black and white back then, and now it's hard to know who the bad guys are.' 'We wanted to play on that a little with Cap being uncomfortable with the way S.H.I.E.L.D., and in particular Nick Fury, operates.”