Mark Ruffalo recently spoke about the upcoming "Avengers: Age of Ultron" during some downtime, telling USA Today that the scale is bigger and the tone is darker than its predecessor. Ruffalo says:
"Joss [Whedon] is in his full height of his powers. This movie is much more sprawling and epic than the first one. They’re really in an existential, dire crisis. It has a darker quality. The Avengers are really struggling with their own shortcomings and the dissolution of S.H.I.E.L.D. and where they go and who they are in the world. There’s a lot of negativity towards them."
Ruffalo also went into a bit of detail about his character, telling EW that age is having an impact on the development of Bruce Banner:
"I think they set it up nicely now that Banner’s turning 46 years old, and there comes a point where it’s like 'how much more running can I do for myself?'" He was then asked how getting older changes Banner. "Whatever you hate about yourself or you don’t like, when you get to be 46 years old, you start to say 'okay, no.'
Obviously, you can never really get away from yourself, so you start to live with some of the things you think are so bad. And maybe they’re not that bad. Maybe those things are what you need to do whatever you were never able to accomplish. I think that’s the ticket forward for Banner, to start to figure out where we go with him, keep that story interesting.
I think there’s a whole relationship with Banner and Hulk that needs to be discovered. There’s a very cool thing happening: Hulk is as afraid of Banner as Banner is afraid of Hulk. It’s in the comics. But because you haven’t really been able to get inside of Hulk’s head, because the [cinematic] technology wasn’t available to make it nuanced enough to do that, and now it is. So now I think there’s a way to do it. Both of these guys are obviously the same guy, and they have got to come to peace somehow with each other. And I think that this confrontation is building along the lines of this film."
Meanwhile, Hayley Atwell has confirmed that her Peggy Carter character from "Captain America: The First Avenger" and the upcoming "Agent Carter" series will make an appearance in "Avengers: Age of Ultron".
Atwell tells EW that her inclusion came about due a night out drinking with writer/director Joss Whedon: "We went out drinking one night and he was like, 'You know, it would be great to write something for you. And I was like, 'Yes, Joss, it would! It would be amazing!'"
Atwell didn't say if her role is either in flashback, or as the elderly version we saw in "Captain America: The Winter Soldier" but chances are more likely the former as set photos from back in April suggest a WW2-era scene ties into the story somehow.
Finally, Kevin Feige has talked to IGN about Aaron Taylor-Johnson's Quicksilver in the film and how it will differ considerably from the version Evan Peters played in "X-Men: Days of Future Past":
"They may as well be two completely different characters. We are very much playing up two things that [X-Men didn't] play with: one is his relationship with his twin sister, Wanda.
The other is, his backstory as an Eastern European child of a war-torn country, and we follow him throughout the whole movie -- him and Wanda -- as it relates to their feelings about the Avengers and how that shifts and changes over the course of the movie. So it's a very different thing than coming out from one, unbelievably awesome showcase sequence of the movie, and much more interwoven throughout the entire movie."