9: Villain
I do not claim to be a comic book aficionado but I can tell you that I enjoy the hell out of the adaptations, particularly the great villains. Who didn't love Joker or Bane (cartoonish voice and all)? Outside of having to either develop a new Batman as a character or explain Nolans interpretation of Batmans involvement in the film, Snyder and Goyer will inevitably have to introduce a worthy villain with malicious motives. One also has to remember a film with the grandiose and gravity of The Avengers did not just introduce its villain Loki willy-nilly. He was given characterization in Thor which elevated his dastardly presence in The Avengers. These instances require a slow build up. Even Iron Man 3 connected itself to its future Avengers sequel with panic attacks resulting from the wormhole in The Avengers. You cannot just whip up plot points, especially villains within 2-3 hours in a project this massive. It requires time and buildup; something Marvel understands considering The Avengers 2 is not being rushed into.