In an exclusive interview with io9, the screenwriters of Captain America:The First Avenger, Christopher Markus and Stephen McFeely revealed the following details about Captain America's relationship with the Starks:
One of the big references you have to the other Marvel movies is bringing in Tony Stark's father, Howard Stark. How much of a temptation was there to just make Howard a 1940s version of Tony?
McFeely: We did not know how to do it exactly. Do you make him the opposite of Tony, a straight-laced guy so that Tony is reacting to an oppressive household or something? He's a little closer to Tony…
Markus: I mean, he's Howard Hughes, and we all know where Howard Hughes went. We don't know if Howard [Stark] went quite that far, but when he becomes John Slattery [in Iron Man 2], he's clearly lost some of his sense of humor. So I like considering the evolution of that character. What really fascinated me in the back of my head as we were writing it is that, OK, Steve is fighting alongside this guy, next year he's going to be fighting alongside his son, who is going to appear to actually be older than his father and older than Steve. None of that is in the movie [explicitly], but it's all extra gravy.
And, of course, looking at the comics, the conflict between Steve Rogers and Tony Stark has been a huge driving force over the last few years. Is that something you wanted to allude to or build into Captain America?
McFeely: We definitely wanted Steve to have a relationship with Howard so that, if Joss [Whedon] chooses to use it, Steve can turn to Tony and say, "I knew your father, and I have this opinion about you, I have this opinion about him." So if they have a conflict later that there's a resonance there.
Markus: I have no idea – literally - whether we're headed for Civil War or anything like that. They're just a great contrast. Tony Stark is never going to wave a flag.
McFeely: It's safe to say that in The Avengers they certainly have friction.
While it's still very, very early, its interesting that the screenwriter immediately picks up on the fact that the interviewer is referring to Civil War in his questions. It's probably safe to say that we wouldn't see a Civil War storyline until a third movie at least. Still, if that's the direction Marvel is heading, they'd need to start laying the groundwork in the very first movie. Would you guys be interested in seeing the Civil War storyline on the big screen or would you like to see a different story?
Civil War is a 2006-2007 Marvel Comics crossover storyline built around a self-titled seven-issue limited series written by Mark Millar and penciled by Steve McNiven, which ran through various other titles published by Marvel at the time. The storyline builds upon the events that developed in previous Marvel crossovers, particularly Avengers Disassembled, House of M, Decimation, and Secret War. The tagline for the series is "Whose Side Are You On?" The premise of Civil War involves the introduction of a Superhuman Registration Act in the United States. Similar acts have been used as literary devices in Watchmen, Uncanny X-Men, DC: The New Frontier, Powers, and Astro City, though never on a scale such as permanently altering an entire pantheon of established pop culture icons.