There are rumors that Quicksilver and the Scarlet Witch are going to be in ‘Avengers 2,’ though I have to ask why, especially when they’re two of the most uninteresting characters – in my not-so-humble opinion – in the Marvel canon.
Why don’t they go in another direction, and leave the Maximoffs to Fox (both Quicksilver and the Scarlet Witch are mutants, which appears to include them in the deal that Fox has with Marvel. If I recall Fox got a bit out of sorts of the “Mutant X” television series in 2001, so they take their mutants very seriously. If they were to be used by Marvel, there can’t be any mention of their mutantness).
Though if they’re looking to introduce a new character, perhaps they should take a look at the Vision.
Not only is he awesome, they would also have to introduce Ultron (perhaps during the upcoming Ant-Man film?), which would mean that they could introduce the theme of technology run amok, which is always a good one.