Joss Whedon, who will return to direct Marvel's The Avengers 2 in 2015, gave an interview to Crave Online and talked about the use of Quicksilver and Scarlet Witch in the superhero sequel.
He also addressed X-Men: Days of Future Past, which will also feature Quicksilver. Coming Soon transcribed part of Whedon's interview:
"[They're] a huge part of [Marvel's The Avengers 2]...I'm really excited about it. I don't know what they're doing and I'm determinably not knowing. They'll do their thing. I have to do mine."
Quicksilver will appear in both The Avengers 2, a Marvel Studios production, and X-Men: Days of Future Past, a 20th Century Fox movie. Marvel Studios president Kevin Feige told SuperHeroHype last summer how both companies could use the same character:
"We both have them [Quicksilver and Scarlet Witch]. There's a specific arrangement with those two characters that would allow us to use them with Avengers, but not discuss or reference their mutant or Magneto-related lineage. They can use them as mutants and as Magneto's relatives, but cannot have anything to do with The Avengers."
In the comics, Quicksilver and Scarlet Witch are Magneto's children.
Whedon also discussed his failed Wonder Woman movie project:
"It's like grief," he says. "There's a period of anger where you're like, 'Hey! Remember all those times where I told you it would have worked? They believed me and it did! So now I'm going to get angry about stuff that I had pretty much dealt with.' You do kind of want to have a slap-line of everybody you had previously worked for. But I'm luckier than most people, so you get over that."