We’ve been hearing bits and pieces about various elements of ‘Avengers: Age of Ultron,’ from the origins of Ultron and Vision to who Andy Serkis might be playing in the film. But we haven’t heard a whole lot about what’s up with Scarlet Witch and Quicksilver, the super-powered twins teased at the end of ‘Captain America: The Winter Soldier.’ What we do know is that they’re going up against the Avengers. What we haven’t known is why…until now. Plus, Marvel has released a bunch of photos from the upcoming sequel, in case you felt like Hulking-out.

In a new interview with Digital Spy, Elizabeth Olsen opens up about the motives of Scarlet Witch and Quicksilver, which have a whole lot to do with Tony Stark’s past in weapons manufacturing:

Our characters have a lot of anger, especially towards Tony Stark, and we want revenge. We meet Ultron, and he’s someone who preaches peace and…believes what we believe, which is that the Avengers create destruction and that Tony Stark’s bomb is responsible for killing our parents.

But Scarlet Witch and Quicksilver won’t remain on Ultron’s side for too long, and by the end of the film, Olsen says her character will have to do some cleaning up:

My character ends up really having to deal with her ignorance. A lot of problems that happen towards the end of the film are her responsibility.

We’re particularly interested in seeing how the twins go from fighting with Ultron to fighting against him. Could Vision have something to do with their change of heart?

You can take a peek at new photos of Quicksilver and Scarlet Witch in the gallery above, which also features plenty of Hulk shots and a few behind the scenes images, in which director Joss Whedon wears a rather Indiana Jones-esque hat. We’ve seen a few of these images before via previously released stills and trailers, but there are some cool new photos, including one of Mark Ruffalo’s Bruce Banner preparing to unleash the Hulk.

‘Avengers: Age of Ultron’ hits theaters on May 1.