Joss Whedon was interviewed about Avengers 2, and among all your generic “Oh, it’s such an honor” and “We’re all hard at work” and “Go see Iron Man 3″ statements, he also mentioned this: “Oh, I’ve got these two characters, two of my favorite characters from the comic books; a brother/sister act. They’re in the movie, that’s exciting.”
Now, obviously if you hear “Brother/Sister” in relation to the Marvel Universe, your brain is going right to Wanda and Pietro, because, well, they’re siblings, but they also sometimes sleep together. Even in the versions where they aren’t explicitly doing that, well, Wanda gives birth to a kid with super speed powers and we never really learn who the father is, so, make your own assumptions. Still, try to put that aside for a moment, forget about the creepy incest plots, and try to think of any other brother/sister combos in the Marvel Universe. I sure can’t think of one, and when I googled it, all I got was a million pages of Wanda/Pietro fan fiction.
So, assume for the moment that it is them. Apparently, despite being mutants, they spent enough time with the Avengers that Marvel was able to negotiate a hazy shared rights deal with Fox. So, theoretically Marvel could have them in The Avengers, while Fox had a completely different pair in one of their X-Men movies. Still, I think we can assume that’s not gonna happen. Fox had their chance for Quicksilver when they wrote a super speedy character in X-Men 3, but they chose to go with “Dude we just made up.” So, that’s dealt with, but how do you introduce them into the movie. There’s been no mention of mutants in the Marvel movie universe. I have to assume that along with the rights to Quicksilver and Scarlet Witch comes the rights to mention the concept of mutants, but still, when they’re the only two that appear to exist in this world, it’s gonna be a might bit distracting. But the only other options, claiming they got their powers another way or just not explaining them, are worse. Claim the powers come from somewhere else, and you might as well write off all the nerds in the world, as the X-Men fans and the Whedonites go to war, and destroy each other. But just don’t explain the powers, and you’ve gutted the characters. They are mutants. Not only mutants, but the children of the grand high terrorist mutant. That’s the defining characteristic of these two. Don’t use that, and what’s the point of even having them?
Seems like too much effort, really. Let’s just have Captain Marvel instead. He’s fun. Or She-Hulk. Ooh, and Daredevil. But they don’t use their powers. They’re just lawyers. And the whole movie is just then defending the Avengers against a lawsuit over all the damage that was incurred during the Chituari invasion. Best movie ever.