I think it's safe to say that pretty much everyone has heard rumors about the next Avengers movie. For some time it's been thrown about that Scarlet Witch and Quicksilver would be appearing in both Avengers: Age of Ultron as well as X-Men: Days of Future Past (with different actors due to the different studios involved).
There's also been quite a bit of buzz as to who would be playing them. Today it's been officially confirmed. Elizabeth Olsen has been cast as Scarlet Witch and Aaron Taylor-Johnson will play her brother Quicksilver.
The two actors are no stranger to each other as both will be appearing in the 2014 Godzilla movie (due in May). Taylor-Johnson is also known for playing Kick-Ass in both movies.
What should be interesting is how they will be introduced. With all things mutants taking place in the Fox movies, Marvel Studios will have to come up with another solution in explaining how the two siblings gained their powers. It could just go unsaid and maybe they'll just be two more "agents" under S.H.I.E.L.D.'s observation and training.
Avengers: Age of Ultron is due in theaters on May 1, 2015.
Source: USA Today