'Black Widow': Rachel Weisz, Florence Pugh, David Harbour and More Dish on Their Characters (Exclusive)

ET's Ash Crossan got the scoop on the upcoming film right after the epic Marvel panel at Comic-Con on Saturday.

Fans of Black Widow got loads of exciting new details on the upcoming film at Comic-Con 2019!

After the film’s cast was officially announced during the Marvel panel on Saturday, ET’s Ash Crossan spoke with Florence Pugh, David Harbour, Rachel Weisz and O.T. Fagbenle about their characters in the upcoming MCU movie. 

"Ten years ago, if you told me that I would be standing in Hall H and presenting this footage to all the fans, it would have seemed incomprehensible," star Scarlett Johansson raved backstage after the panel. "Especially with this lineup and this incredible cast and [director] Kate Shortland at the helm. It’s an actual dream come true, very very exciting."

While some details about the upcoming film are still unclear -- like when exactly it takes place or how Johansson's character's death in Avengers: Endgame factors in -- we did get some new clues about the supporting cast in Natasha Romanoff's story.

Midsommar star Pugh, who plays Yelena Belova, said that her character has a "sister" bond with Natasha. A brutal fight between the two in the panel's teaser footage, however, proves there's definitely some unfinished family business. "I get to have a love and hate relationship with her, all the time," gushed the actress, who was reveling in the "pinch-me moment" of her very first Comic-Con. "It's great!"

Weisz couldn't dish on whether or not she gets to spar with Johansson in the film, but it seems her character, Melina, would be a more-than-worthy opponent.

"She’s been cycled through the Red Room Widow program five times, so she’s pretty highly-skilled, trained, spy-assassin who’s also pretty interested in science," The Favourite star revealed.

During the panel, Fagbenle teased that his character, Mason, has a "romantic undercurrent" with Natasha, but it seems the two have never quite been on the same page

"In rehearsals... we kind of like, filled out the backstory between the two a little bit," he explained. "I guess it’s one of those things where it’s like, on the precipice, on the cusp of something happening, but they never quite know how to make it actually work."

As for Harbour, the Stranger Things star's Black Widow character -- Alexei, aka the Red Guardian -- may bear a familiar, if frosty, resemblance to a character Natasha has worked closely with in the MCU canon.

"In the Cold War, there was a nuclear arms race and the Americans developed all these armaments, including Captain America," the actor explained of his character, who has a backstory in the Marvel comic canon. "The Soviets retaliated by creating their own version, called the Red Guardian. But he’s somewhat different than Captain America. He’s a very complicated guy, and that’s what I love about him."

Harbour raved about his admiration for many of the MCU's heroes -- and the way viewers get a chance to explore the way their altruistic actions and desire to do good come into conflict with their personal flaws. "Alexei, he's a tremendously flawed guy, and also has tremendous humor and tremendous heart."

In April, ET spoke with Harbour about his then-rumored participation in the film. At the time, the leading man shared a thorough knowledge of the production while refusing to confirm his involvement.

"Look here's what I will say. It's being directed by this woman Kate Shortland who is a phenomenal director," he said at the time. "She directed a movie called Lore. She's a phenomenal director, so what's really exciting to me about it is it's gonna be like a real deep, interesting film. And so yeah, I'm just excited for it as a film as well as a superhero movie."

Endgame directors Joe and Anthony Russo and screenwriters Christopher Markus and Stephen McFeely also had panels at Comic-Con on Friday, where they discussed making the film and why certain things were cut. Check out the biggest revelations right here.

Black Widow is set to be released on May 1, 2020.