After last month's confirmation that Quicksilver and Scarlet Witch will be a part of The Avengers 2, director Joss Whedon spoke about how important these characters are, and how he doesn't want to know how they will be used in Fox's X-Men: Days of Future Past.
"[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."
Both 20th Century Fox and Marvel Studios share the rights to these characters, with each studio following certain guidelines. Pietro Maximoff (Quicksilver) and Wanda Maximoff (Scarlet Witch) are the mutant children of X-Men's Magneto, with Quicksilver possessing super-human speed and Scarlet Witch having the power to control probabilities. They also appear in The Avengers comic book line, although Fox cannot mention anything that is related to the siblings' Avengers story and Marvel can't use anything in regards to their mutant lineage with Magneto.
We reported earlier this month that Aaron Taylor-Johnson is being considered for Quicksilver in The Avengers 2. Actress Saoirse Ronan has been reported to be the "model" for Scarlet Witch, although it isn't known if they will bring her on board. Evan Peters has already been locked in as the character in X-Men: Days of Future Past.
Joss Whedon also spoke about his massive success as of late, and earlier projects like his failed Wonder Woman movie that never got off the ground at Warner Bros.
"It's like grief. 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."
No production schedule has been released for The Avengers 2 at this time.