"Erik is very wary of new elements in his life and of getting close to someone again. He does so with Charles as much as he can with anyone. We wanted to have a believable journey to the point where their devastating rift begins.
"When Erik and Charles have their parting of the ways, audiences will realize that great things could have happened if they had joined forces forever."
Erik is also hesitant to join Charles on his mission to save the world from itself. Why, asks Erik, is humanity even worth saving? "Erik is quite Machiavellian; he believes the end justifies the means," Fassbender explains. "He has no regard for humans, and feels they’re inferior."
Erik’s cavalier attitudes about humans stem from his childhood, which couldn’t have been more different from Charles’ life of privilege. Erik had to survive without parents, and as a youngster was forced to endure unimaginable hardships.
X-Men: First Class introduces Erik with a recreation of the scene that opened the original X-Men, set at the Auschwitz concentration camp, in the 1940s. There, young Erik, horrified when the Nazis separate him from his parents, reveals his mutant abilities, bending the camp’s metal gates.
X-Men: First Class then picks up after that scene, as Erik, still a youngster, becomes the test subject of a Dr. Schmidt, who is determined to fully unleash and harness Erik’s powers.
"Matthew and I had always admired the power and impact of the concentration camp scene in X-Men, which really informs the character of Erik," says co-screenwriter Jane Goldman.
"And Matthew wanted to explore what happens next to Erik. What you see will change the way you feel about Erik, and allow you to see him through fresh eyes."
Twenty years later, Erik now a grown man, has one mission in life: track down and kill Dr. Schmidt (whom we’ll again meet in a very different guise).
Erik is a force of fury and hate, hunting Schmidt and the other Nazi doctors whom he believes turned him into a kind of Frankenstein’s monster.
Even as Erik finds his first friend in Charles and is embraced by the other members of the team that will become the X-Men, he never veers from his mission.
"Erik is totally driven; if Charles or anyone gets in his way, he’s going to put them down," says Fassbender.
Vaughn had seen Fassbender’s critically acclaimed performances in 300, Hunger, and Inglourious Basterds, and after Fassbender’s impressive audition, cast the actor as Erik.
"Michael gives Erik an interesting attitude, and Erik is really straight-up cool," says the director.
Fassbender, who was eager to play the complex character, notes that when he got the script, he thought it was "truly clever. There were real consequences to each action in the film. It wasn’t all guns blazing. There was so much more going on, many layers in the writing, and I was very impressed with that."
Fassbender also notes that he did not draw on the previous films to develop his interpretation of Erik. "The source material is in the comic books. We were really starting from scratch in order to present a fresh look at the material."
X-Men: First Class is out now.