With reporting by Kevin P. Sullivan

The Scarlet Witch and Quicksilver -- aka, Pietro and Wanda Maximoff -- have been a part of Marvel Comics since they were first introduced as characters in the '60s, and have been members of the Avengers for almost just as long.

So far, though, fans of Marvel's movies probably only really know them as the weird pair of "miracles" that appeared in the post-credit sequence for "Captain America: The Winter Soldier." But all that's about to change when they finally make their on-screen debut together in "Avengers: Age of Ultron" a month from now, as played by Elizabeth Olsen and Aaron Taylor-Johnson.

MTV News visited the set during filming in June 2014 to talk with the newest additions to the Avengers cast, and can now reveal what we learned from Aaron and Elizabeth about how they'll appear in the movie.

The two have been working hard on their European accents.

When we first heard Pietro Maximoff's first line of dialogue in the latest "Avengers: Age of Ultron" TV spot a few weeks ago, some had a hard time placing where exactly his distinct Eastern European accent really comes from. That's because according to Olsen, the country in which the two characters grow up doesn't exist.

"It's a make believe place, so its something that Aaron and I, with the dialect coach, kind of create together," she told press at the set visit. Of course, she wouldn't disclose the name of that place, but it's a safe bet that it's probably "Transia," their fictional country of origin in the comics.

"When I spoke to Joss [Whedon] about it a long time ago and he approached me for the role, um, it was one of the things I kind of wanted to keep," Aaron Taylor Jonson said of the characters' history. "If I could kind of embrace the sort of, the roots, where he's from, you know, being Eastern European, it would be great to do some kind of accent to impart that kind of feeling so -- so I'm glad that we're doing it."

Aaron Taylor-Johnson doesn't have any hard feelings about getting to Quicksilver second.

While this is the first time Pietro and Wanda will be on screen together as brother and sister on film, this technically isn't the first movie to feature Quicksilver's speedster powers -- he also appeared in "X-Men: Days of Future Past." But Taylor-Johnson isn't worried about getting beat to the punch... in part because he hasn't actually seen 'Days of Future Past' yet.

"I don’t feel threatened," he said. "It's just that's one thing and we're doing something different. But yeah, I haven't watched it to kind of be like, 'Oh, they're doing the Slow Mo Super Speed kind of Action shots.'"

"I bumped into him at Comic-Con way back before this," he said of his former "Kick-Ass" co-star Evan Peters, who played the character in the "X-Men" film. "I said how funny it was but yeah, it was all easy and cool. It's like, it's not like-- I don't get very sort of competitive or you know, find it like awkward or anything."

Scarlet Witch's powers will blow your mind (literally).

We've seen her telekinetic abilities already in the post-credits tag of "The Winter Soldier," and we know that she'll be getting into the psyches of all our favorite Avengers. But Wanda's psychic powers are much more complicated and empathetic than that, Olsen told us.

"I am able to go into someone's head and they'd never see," Elizabeth said "They're almost like, I can, I can feel and see what they feel and see, so it's not just me manipulating them. What I love about [Wanda] is that in so many superhero films, emotions are kind of negated a bit, but for her everything that someone else could feel like their weakest moments, she physically goes through that same experience with them, which is pretty cool."

But! There's one caveat to her powers, she says: "I don't think that includes robots."

"Age of Ultron" wants to try something new with super speed.

We've seen speedsters on camera before -- the Flash, Daphne Millbrook from "Heroes," and even Quicksilver once before. But this is the first time we're ever getting a speedster in the cinematic Marvel Universe, and according to Taylor-Johnson it will not disappoint.

"I go at such super speed that it's literally, yeah, an elbow or an shoulder would send someone kind of flying," he said. "It's the force of impact of my powers. And depending on when I'm slowed down, it makes the character very vulnerable at times, but he's at super speed, no one really can kind of keep a track on it."

But does Aaron think he could win a foot race with the other Avengers if he DIDN'T have the benefit of movie magic? "I mean, it would be pretty embarrassing if I couldn't," he said, laughing. "It depends. If they're in their costumes I would. I think I would be super fast. Hemsworth would be fast, but he's got a lot of weight there."

Olsen worked with a dance choreographer for her energy blasts.

"I can like manipulate energy away, so that's what the red stuff is that we're playing with," she said, noting that she worked with dancer and choreographer Jenny Wade to get the feel of how that energy should flow from her. "It's been so fun, because you can't be like well, how does this magic witch hero move? Like there's nothing physically that you can just reference from dance or, you know, martial arts or anything like that."

"It's funny, because everyone's doing stunt practices and choreography, and she and I are just like doing weird moves and like, pretending like we're making things shoot out of our hands," she laughed. "I can't get injured that way and I feel not as tough as everyone, but it's super fun."

Yes, their costumes were designed to look like civilian clothes.

Pietro and Wanda don't have the same polished look as established heroes like Captain America, Thor and Black Widow -- and that was done, very indirectly, to reflect their origin in the comics.

"Cause it’s so early on, I'm just more of a civilian really. Like they're more sort of Eastern European kind of Travelers that are kind of just, um, you know, uh, picking out clothes as they go along," Taylor-Johnson added.

The way that we've designed costumes is based off of these two kids you know, being on their own and using whatever they can to their best ability," Olsen said. But she's also pretty happy she won't have to wear any of Wanda's more revealing outfits.

"The first thing Joss ever said to me before I even got the job, when we were first meeting, he said, 'when you look at the images, look at the comics, know that we're not making you look like that. You will not have to wear a bathing suit or look like a porn star.' So that made me feel great."

Don't worry, the film will have a sense of humor.

Sure, everything looks like it's going to get really terrible for the Avengers, but that doesn't mean they can't take a break to be a little funny once in a while.

"The thing is the Marvel Universe in general is everything's not taken seriously -- in a sense of even when there's points of real drama. but I love that there's a lot of sarcasm and humor to it," said Taylor-Johnson.

Olsen agreed, speaking in particular about their first scene with an Avenger, Clint "Hawkeye" Barton. "I think there's a lot of humor," she said. "Jeremy Renner's character is hilarious for some reason to me, and he’s like a big grump."

Most of all, the two are excited to be part of the Marvel family.

"You feel like you're in good hands," Olsen said of working with director Joss Whedon in particular. "He's such a huge fan of [Wanda] and it's really awesome to get to have that. I think he is enjoying also getting to have the experience where he gets to create it, because he is such a fan of creating these strong, amazing women."

"The Marvel guys, they totally understand," Taylor-Johnson also said. "It comes to their characters, you know -- they're a studio that really care about their characters, and have real creative input and are totally for that."

Want to see more of the twins in action? Check out this featurette from Marvel in anticipation of "Avengers: age of Ultron," which comes out on May 1st.