Though production is already well underway on director Bryan Singer’s sequel X-Men: Future Past in Canada, a late addition to the cast has been made.  Singer announced today on Twitter that American Horror Story star Evan Peters will play Quicksilver in the star-studded superhero pic, though this may make things quite complicated for Marvel’s The Avengers 2.  In comics lore, Quicksilver is a mutant capable of moving and thinking at superhuman speeds.  He also happens to be the son of Magneto, along with his twin sister Scarlet Witch.  While this is certainly a fascinating cast addition to the time-bending X-Men: Days of Future Past, it could very well affect Marvel’s Avengers sequel as Joss Whedon only recently revealed that he’s written both Quicksilver and Scarlet Witch into his script.  Hit the jump for more.

Here’s how Singer broke the news of Peters’ casting and the character addition on Twitter:

Late last month, Joss Whedon revealed that he was including two of his favorite comics characters in The Avengers 2, and Kevin Feige later confirmed that Quicksilver and Scarlet Witch are indeed poised to appear as part of the Avengers team in the follow-up.  Legally speaking, both Marvel and Fox posses the right to include Quicksilver and Scarlet Witch in their feature films.  However, given that Days of Future Past will hit theaters next year while The Avengers 2 doesn’t open until 2015, audiences may be a tad confused at seeing two iterations of the character onscreen.

As Marvel/Disney and Fox are competing in the marketplace, the two studios don’t exactly share their creative material.  As such, the version of Quicksilver in DOFP is likely to be quite different from the Quicksilver we’ll see in The Avengers 2.  For instance, Marvel doesn’t have the rights to X-Men so they can’t mention the fact that Magneto is Quicksilver’s father, and Fox doesn’t have the rights to The Avengers so they can’t allude to the fact that Quicksilver also hangs out with Tony Stark and the gang in his free time.

It’ll be interesting to see if Marvel balks and scraps plans to include Quicksilver, or if the studio—likely bullish from Iron Man 3’s billion dollar box office take—will stand tall and move forward with its own plans for the character.  Whatever the case, we’ve got a fascinating comics conundrum on our hands.  With regards to Days of Future Past, though, I'm interested to see how the inclusion of Quicksilver affects Michael Fassbender's young Magneto and/or Ian McKellan's present day Magneto.

X-Men: Days of Future Past opens on July 18, 2014, and The Avengers 2 hits theaters on May 1, 2015.