Marvel movies are all the rage these days, especially with the recent success of the superhero team up in the Avengers. But before the sequel to this highly successful film comes out, Marvel is busy churning out the follow-ups to the individual movies of these superheroes. And it looks like two Marvel universes will be combined in the upcoming next movie of Captain America.

Reports have emerged that actor Robert Downey Jr. is in deep talks to appear as Iron Man in the Captain America 3 plot. According to a report by Variety, Downey Jr. is now in the final round of negotiations to reprise his role as Tony Stark in the third Captain America movie which will start shooting this spring.

If this is true then this would mean that aside from his upcoming roles in The Avengers: Age of Ultron, and Avengers 3, we will be seeing billionaire inventor Tony Stark alongside Chris Evans as Captain America. It is also being speculated that Iron Man's appearance in the Captain America universe signals that the Civil War storyline that the comicbooks followed will be the basis for the Captain America 3 plot.

So what exactly will the storyline be for this next Captain America movie? Well, according to Variety, the movie will put Tony Stark in direct opposition against Steve Rogers (Captain America), and their point of conflict will be about the Superhero Registration Act. This law calls for anyone who possesses superpowers to register with the U.S. government, and by doing so consents to acting as part of the police force for the government. Reportedly, the Captain America 3 plot will revolve around Iron Man supporting the act, while Captain America opposes it.

Let's hope that the deal pushes through, because if so, then Captain America might not be facing villains of the usual kind, but someone who he has considered a teammate, in the form of Iron Man himself. Further details of the Captain America 3 plot are expected any time so stay tuned!