Several theories and reports related to Avengers: Age of Ultron have hinted that the film will build towards a new roster of superheroes, who might join the team in future instalments.

One such strong contender is Ant-Man. Even though Ant-Man has got a solo film set to kickstart Marvel Studio's Phase 3 plan, the character's tie-in with The Avengers might just develop sooner than expected in the upcoming Avengers 2.

Here is how it may play out, as per a theory by CinemaBlend.

Once the title Avengers: Age of Ultron was revealed during the 2013 San Diego Comic-Con, fans of Marvel comics assumed that the film will incorporate the origin story of supervillain Ultron.

"There was one important link to Marvel comic history that fans assumed would fall into the 'then some' category: the introduction of Ant-Man, and the creator of Ultron himself, Hank Pym," states the CinemaBlend report.

However, that assumption was cleared by director Joss Whedon when he stated that he was, "...crafting [his] own version of it where [Ultron's] origin comes more directly from the Avengers we already know about."

Enter Tony Stark.

avengers 2
Fan-made poster of Avengers 2

Clearly it could only be Stark, with his technical know-how and expertise, who could develop Ultron.

However, judging by the latest synopsis for The Avengers: Age Of Ultron, there is a possibility that the origins of the latest menace to The Avengers might be a little closer to the comics than we thought.

"When Tony Stark tries to jumpstart a dormant peacekeeping program, things go awry and Earth's Mightiest Heroes, including Iron Man, Captain America, Thor, The Incredible Hulk, Black Widow and Hawkeye, are put to the ultimate test as the fate of the planet hangs in the balance," the synopsis says.

Notice the 'jumpstart a dormant peacekeeping program' part. That means Stark may not really invent Ultron from scratch but only works off an earlier plan and creation.

So, if Whedon's previous statement is correct, and the following Ant-Man casting scoop is any indication, Hank Pym and Stark's father Howard Stark may have created Ultron together.

John Slattery (who plays Howard Stark) is already confirmed to appear in Ant-Man, and the studio is currently looking to cast a young Michael Douglas (who plays Hank Pym in Ant-Man) lookalike.

So, maybe there is a small reference to the origin of Ultron before Stark takes up the project in Avengers 2, which might get explored further in Ant-Man (possibly during some flashback scenes).

The Avengers: Age Of Ultron will be released on 1 May 2015, with Ant-Man following on 17 July, 2015.