When it comes to Quicksilver in X-Men: Days of Future Past, the question lingers, was he put there before or after Joss Whedon confirmed that the character was being used in Avengers: Age of Ultron?

American Horror Story star Evan Peters was cast as Quicksilver in X-Men: Days of Future Past exactly one one week after Joss Whedon revealed the character held a very important role in Marvel's Avengers sequel, a role which went to Aaron Taylor-Johnson. It was later learned that both Marvel and 20th Century Fox share the rights to this character, although Marvel can't mention any of the character's X-Men history, while 20th Century Fox can't bring up his time with the Avengers.

When asked about the character in a recent interview, director Bryan Singer revealed that Quicksilver was always in the script, while teasing how the character fits into the story.

"Quicksilver was always in our script. Marvel were informed early on that I was using him. The way it'll play out in our movie versus what I believe they are going to do is so different. And this is not an enormous role - he's only on one beat of the movie."

The "one beat" that Bryan Singer is referring to takes place in the kitchen of The Pentagon in 1973, as this speedy character helps Charles Xavier and Wolverine break Magneto free. The scene, which was teased in a photo from earlier this month, also features a guard who comes to Magneto's cell to feed him, only to see Quicksilver suddenly appear in a corner of the elevator.

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So this means Quicksilver was in X-Men: Days of Future Past before they knew he was being used in Avengers: Age of Ultron, right? Not so fast. The director reveals that, early on in the story process, writer Simon Kinberg had planned on using a completely different character for this scene.

"Kinberg had originally employed a young Juggernaut in the same function."

Juggernaut, who literally cannot be stopped by anything once he is set in motion, was played by Vinnie Jones in the 2006 adventure X-Men: The Last Stand. He does not return in X-Men: Days of Future Past, and it was not explained exactly when this character changed over. Perhaps we'll never know the real truth about which came first, the mutant or the avenger.

The director went onto set up a scene where Quicksilver first meets Magneto, who, in the Marvel comic books, is Quicksilver and Scarlet Witch's father.

"Everybody's so slow to him, it gives him an attitude. He's a little impatient. When [Magneto and Quicksilver] first meet, there's a cool, 'Do I know you?' moment."

In related news, some fans were quite surprised when Bryan Singer came back to the franchise he helped build, after directing X-Men and X2: X-Men United. Many thought that X-Men: First Class director Matthew Vaughn would return to direct, but he revealed why he didn't come back in a recent interview.

"It didn't excite me...The thing that was exciting about it was bringing all these actors together. What a cast! But I've worked with great actors and I just thought, 'I've got to do my own thing.' The script was great for X-Men, but I had The Secret Service in my head. And this has always been Bryan's machine. It's come full circle."

Despite not being excited enough to direct X-Men: Days of Future Past, Matthew Vaughn received a story credit on the screenplay, which was written by Simon Kinberg.