New reports are claiming that Robert Downey Jr. has been negotiating his contract for 'Captain America 3', which is set to be released in May 2016.

'Captain America 3' is also rumored to follow the story of Marvel's Civil War, which pits Iron Man and Captain America against each other.

Based on Marvel's Civil War comic book series, the war is sparked when Speedball, a superhero, and Nitro, the villain have a fight each other on national television. In the fight, Nitro creates an explosive blast, killing 612 civilians, including 60 children, all on live TV.

The event pushes the lawmakers to make a Superhero Registration Act, an act that requires superheroes to register their secret identities and where they are based.

The law also says that every superhero should be licensed by the federal government, in order to legally do any superhero crime fighting.

The disagreement between Captain America and Iron Man takes place when Captain America does not agree with the law while Iron Man supports it.

In the comic book, Captain America died during the Civil War.

The deal for Downey to return as Iron Man almost didn't happen, and originally, Marvel wanted to hire Downey for a small role. However, Downey wanted Stark to have a more substantial role in the film's plot.

This did not sit well with Marvel Entertainment chief Ike Perlmutter as he ordered the screenwriters to write Iron Man out of the script entirely, according to the sources.

Downey earned $50 million for 'The Avengers' and a reported $75 million for 'Iron Man 3'. He will collect around $40 million plus backend participation for 'Captain America 3', sources said.

The actor will receive an additional payout if 'Captain America 3' outperforms 'Captain America' (the first film) as well, according to the sources.

Chris Evans is a bigger star now, the fact that 'Captain America: The Winter Soldier' grossed nearly twice as much as 'The Avengers' $371 million in 2011, says it all.