After Robert Downey Jr. announced that he will appear alongside Chris Evans in the upcoming "Captain America" installment, talks about Marvel's Civil War storyline had been making fans excited for the upcoming film.

The third film in the "Captain America" franchise will allegedly feature the feud between Downey's character Iron Man and Evans' Captain America because of their opposing views about the Superhero Registration Act.

Based on Marvel's "Civil War" comicbook miniseries, the Avengers allies find themselves fighting over the new law imposed by the U.S. government. Billionaire Tony Stark (Iron Man) supports the program that requires those with superhuman powers to reveal their identities to the government and work as part of the police force. Meanwhile, Steve Rogers (Captain America) is opposed to this idea, believing that it will only disrupt their civil rights.

This plot makes Iron Man a possible villain in the upcoming "Captain America 3" film, which could also give Downey an interesting storyline in future films from Marvel Studios.

The miniseries launched in 2006-2007 was written by Mark Millar for Marvel comics, while the illustrations were drawn by Steve McNiven.

The deal between Marvel and Downey almost did not push through.

According to an exclusive report by Variety, Marvel is only intending to include Downey in the "Captain America 3" movie in a small support role. However, the award-winning actor wanted his superhero character to have a more significant screen time in the film, which reportedly irked Marvel Entertainment head Ike Perlmutter and asked the writers to remove Iron Man from the script completely.

But Marvel Studios president Kevin Feige would not give up on the project just yet. He made sure that the studios and Downey's camp worked out their differences, and was able to sign the actor for the upcoming film.

Variety also reported that Downey will get at least $40 million plus cuts from the film's revenue for the upcoming "Captain America 3" film.

"Captain America 3" is set for a May 6, 2016 screening date, while the rebooted Civil War comics will allegedly be released by Marvel in Summer 2015.