10. Not Getting Quicksilver And The Scarlett Witch Right
Pierto and Wanda Maximoff are two of The Avengers most longstanding characters, being added to the team roster back in 1965. Since then they've been on and off the team hell, since then they've even fought against the team but despite their introduction as rivals of the X-Men they have largely been part of the mythos of The Avengers for their publication history. But they're also a bit of a hard sell. Power-wise they offer a lot to the cinematic iteration of the team but let's talk personality and character for a second. Think of 3 character-centered characteristics of Quicksilver and the Scarlett Witch got them? Good. Now, take away all the stuff related to Magneto, being mutants and the X-Men - you know, like Genosha, their sister Polaris, The Brotherhood, that kinda stuff. Chances are you're left with 3 words between the two characters: asshole, crazy and quite possibly incest. See, hard sell. But that's where Joss needs to work his magic to make sure he can translate these characters from page to screen. It's a difficult balance because if you change too much of their back story you'll alienate the primary fan-base; if you don't change them enough the general audience will likely not take to it. And if you have them there solely for action sequences involving their fancy powers then everyone will cry afoul. But again, this is where experience as a screenwriter and character developer comes in handy, which Joss pretty much has in spades. Still, the use of the Scarlett Witch and Quicksilver needs some careful consideration in order to give Avengers: Age of Ultron an extra boost.