Captain America is a relic of a less complicated conflict, warring with Nazis and HYDRA, serving as a patriotic figurehead turned formidable force on the battlefield — and even then he was a little square, reflexively moral, sincere, and selfless. But the present in which Steve Rogers is now living is far less straightforward, even when it comes to S.H.I.E.L.D. and the multiple agendas being harbored by its leaders, among them Nick Fury (Samuel L. Jackson) and an enjoyably haughty Robert Redford (who starred in Three Days of the Condor, one of the films cited as a Winter Soldier touchstone) as Alexander Pierce, head of the World Security Council and one of Fury's old cohorts. Steve cares about country, truth, freedom, but what's at stake in Winter Soldier is control on a global scale, and no one's being completely honest about what they're after.
While Winter Soldier makes plenty of room for fight sequences (including a particularly nifty one in an elevator and several bruising encounters with the baddie of the title, played by Sebastian Stan), its primary conflict isn't good versus evil — it's over very different ideas of the greater good, with S.H.I.E.L.D. at the center. As intimidating as the Winter Soldier is when he arrives, a dark figure snapping into focus in the middle of the street, he's not the movie's only or even main antagonist — its villains don't all come as clearly marked with a black mask and bionic arm. Steve still has it in him to make a potentially cornball speech sound moving — "The price of freedom is high, and it's a price I'm willing to pay!" he says in this one — but the film also raises questions about the nature of superheroes. He's a trusted, beloved presence participating in missions he's not always sure he supports; Cap is aware that secrets are being kept from him, and his place as one of S.H.I.E.L.D.'s most public faces means it gets to benefit from his credibility.
Unlike Thor, unlike Tony Stark, Steve Rogers doesn't have another life to go back to when he's not on call. As he points out, he's always wanted to be a soldier, even if he's ended up becoming a symbol in the process. Winter Soldier serves as a connecting point between the more outsized Marvel characters who've already had films of their own and the ones who work for the organization that ties them all together, day to day. Steve doesn't quite fit in either category (it's another way in which he stands alone) but by upending him into a present where he's confronted with nebulous ideas about surveillance, preemptive attacks against potential enemies, and institutions that can't be trusted, he seems all the more poignant a figure. He's Captain America, and for now, there's no place for him in this world other than in a museum.