"Avengers: Age of Ultron" will introduce 'the twins' referring to Quicksilver and The Scarlet Witch. Actor Aaron Taylor Johnson and Elizabeth Olsen talk about their changing onscreen relationships and their initial reluctance to join the top comic book movie franchise.

From I Am Rogue, young stars Aaron Taylor Johnson and Elizabeth Olsen share their Avengers experience. The former Kick-Ass star said he was initially reluctant to be just another hero:

ATJ: "Just before I started Godzilla I met Joss... He said to me, 'Do you want to be in Avengers 2? There is a super hero I'm thinking of for you.'"

He continues: "The thing for me was for [Whedon], 'Why add any more super heroes to this thing?' He said, 'No, there are these two characters that I want to bring in to like f*** with the Avengers and not be just an add on.' He told me a little bit about the writing and I said that the only reason I would want to do it is if it is a character that can still stand out.

It was not a negotiation tactic, but he was just honest about what he felt. He was a super hero in a title role in Kick Ass: "You know, you've got five of the most awesome super heroes, ten I suppose, there are about ten Avengers now, and they are all movie stars... You've got such a huge cast, what the hell difference is it going to make if I come on the scene? So it was the character and that took about a year of going back and forth about it. It took a while but I'm super happy to be in that one."

Elizabeth Olsen explains how they shifted from being lovers in "Godzilla" to twins in the Avengers sequel: "We have a much more closer connection in Avengers actually... Because we play these twin brother and sister that never leave each other's side. In Godzilla, the whole point is that we are apart. So it's totally different, but nice to have known him and his family, and him as a person as well as an actor before doing that."

She also touched on the possible comparison with Fox's "X-Men" franchise which also has a copyright to their characters. They are supposed to be Magneto's kids, but they cannot use that origin: "I didn't really read any of the feedback. I just have one friend that works at Bad Robot, so she is on all these blogs all the time, and she'll send me her favorites ones. She only sends me the good stuff but I like that people were stoked about our characters, and everyone was like, 'What are they? Who are they? What's their excuse going to be because they can't talk about X-Men?'"

"Avengers: Age of Ultron" will be released on May 1, 2015.