The model I'm always trying to build from, my guiding star, is The Godfather Part II where a ton has happened in-between and it's a very different movie [from The Godfather], but you don't need any information: it's there in the film." In October 2011, Kevin Feige, president of Marvel Studios said the studio was beginning to look at their Phase Two films, which would start with Iron Man 3 and would culminate in a second Avengers film. By being the next thing that should happen to these characters, and not just a rehash of what seemed to work the first time.
I can't assume that everybody went to see Thor [The Dark World], Captain America [The Winter Soldier], and Iron Man  in-between.
I have to go from one movie to the next and be true to what's happened, but not be slavish to it ...
Avengers: Age of Ultron premiered in Los Angeles on April 13, 2015, and was released on May 1, 2015, in North America, in 3D and IMAX 3D. Having killed Strucker, he recruits the Maximoffs, who hold Stark responsible for their parents' deaths by his company's weapons, and goes to the base of arms dealer Ulysses Klaue to obtain Wakandan vibranium.
The film received generally positive reviews from critics and grossed over $1.4 billion worldwide, making it the seventh-highest-grossing film in history and the fourth highest-grossing film of 2015. The Avengers attack Ultron and the Maximoffs, but Wanda subdues them with haunting visions, causing the Hulk (Banner) to rampage until Stark stops him with his anti-Hulk armor.
When asked about his decision to return, Whedon said, "Avengers 2, it wasn't a tough decision.