Breaking: It’s only a matter of time before Marvel Studios makes it official, but it looks like Joss Whedon has found his “brother-sister act” of The Avengers: Age of Ultron. Whedon, who’s directing and writing The Avengers sequel while pulling triple-duty launching Marvel’s Agents of S.H.I.E.L.D. television series on ABC and overseeing other elements of the Marvel Cinematic Universe, first revealed that he intended to expand the roster of Earth’s Mightiest in the sequel while doing press for Iron Man 3.

While being vague at first, Whedon was quick to confirm this summer that Captain America, Iron Man, Hulk and Thor would be joined onscreen by two new characters in Quicksilver and Scarlet Witch come 2015, and now we know who’s playing each character.

It was almost four months ago when Aaron-Taylor Johnson (Kick-Ass) was listed as a top contender for the role of Quicksilver, a part he later confirmed to be in talks for – not only for negotiations, but with Whedon himself to determine how they’d adapt the super-fast character for the film. After months of being questioned about the role, Johnson will soon be able to do it with a little more confidence since – according to Latino-Review – it’s a done deal and the casting is confirmed.

With Samuel L. Jackson, who plays SHIELD director Nick Fury in the franchise – slipping word yesterday that Elizabeth Olsen is also “confirmed” for The Avengers 2, an actual “official” announcement for the pair from Marvel should be coming imminently. LR recently scooped the Bradley Cooper casting for Guardians of the Galaxy the day before it was made official, and in this case since they are a duo, it would be a logical to announce both at the same time.

Interestingly, Marvel and Whedon are going for proven and high-in-demand talent for the two supporting characters, instead of using the established franchise stars – who are already proven at the box office and among fans – to help propel the careers of relative unknowns (a la Chris Hemsworth). That being said, the acting talent of Olsen and Johnson is unquestionable, and their additions help bolster – and add youth to – an already all-star roster.

Thor: The Dark World on November 8, 2013, Captain America: The Winter Soldier on April 4, 2014, Guardians of the Galaxy on August 1, 2014The Avengers: Age of Ultron on May 1, 2015, Ant-Man on July 31, 2015, and unannounced films for May 6 2016, July 8 2016 and May 5 2017.

Follow Rob on Twitter @rob_keyes for your Marvel movie news!

Sources: Latino-Review