Dueling Quicksilvers appear to be a given. Unless Fox has a change of heart, a character named Quicksilver will appear in a cameo in Bryan Singer's "X-Men: Days of Future Past." Joss Whedon has also let it be known that the two characters he hopes to add to the "Avengers" mix for the upcoming sequel are Quicksilver and the Scarlet Witch. How can this be?

HitFix's Drew McWeeny broke the news that both Marvel and Fox have rights to the characters through their respective franchises -- with a catch. Fox can't bring up the word "Avenger" in association with Pietro and his mentally unstable sister Wanda, and Marvel can't reveal that the two are mutants, or that they are the offspring of the infamous Magneto. And still, both companies appear set on giving moviegoers two versions of one of Marvel's least popular secondary characters. (Hopefully we'll just get one Scarlet Witch out of this.) Today it was revealed that Aaron Johnson is Marvel's first choice for the role. If he does come on board, he'll deal with media attention he's never seen before, and it creates a youthful new dynamic for the series.

With that in mind, McWeeny and two other Marvel experts on the HitFix staff provide some insight on the casting in another installment of our "3 on 3" series.

1. Is Quicksilver still Quicksilver if he's not a mutant?

Gregory Ellwood: In my opinion, no.  Quicksilver and the Scarlet Witch were the first bridge between the world of the X-Men and The Avengers (the Beast was the second).  By eliminating the mutant equation and, more importantly, the idea that he's Magneto's son you're basically gutting the character. You might as well just put the Whizzer on the team.

Drew McWeeny: No. No more than any other X-Man would be. When you take Wolverine's mutant power away, he's Freddy Krueger with better fashion sense. It seems sort of unreal that Fox holds an entire corner of the Marvel universe hostage, because mutants define them as much as any other superhero. Still, that's the deal, so it seems to me like "The Avengers 2" should be the one that blinks, that they should find someone else to play that part. I know that's not what Whedon wants to hear, but why include a character when you're handcuffed from the start from showing him properly.

Kristopher Tapley: This seems like the key question. The entire essence of the character has to be changed for "The Avengers," so it's almost like why bother? It really just feels like a spoiled opportunity to share a universe. Universal and Miramax figured it out for Michael Keaton on "Jackie Brown" and "Out of Sight," though of course, the stakes are considerably different here. It could have just served as a curiosity (one that would have, by the way, helped both films). But to answer the actual question, if Quicksilver is not a mutant, then no, he's not Quicksilver. He's just some guy named Quicksilver…unless, that is, we're looking at a "House of M" scenario with a de-powered Quicksilver. Hmmm…

2. Assuming the Scarlet Witch is around her brother's age, is this a youth movement for The Avengers?

Gregory Ellwood: Yes, and smartly so. Right now, only Johansson and Hemsworth are the only regular cast member under 30 (Thor will enter his third decade in August) and you've got four primary members over 40.  If Marvel doesn't bring in younger cast members Earth's Mightiest Heroes are going to get awful grey awfully soon.

Drew McWeeny: Let's hope so. Part of what makes the Marvel Universe great are those moments where the teen heroes like Spider-Man run into the waaaaaaay more adult heroes like Iron Man. It creates a sense that it's generational, and not just one moment where all the heroes happened at the same time. I think they've got to actively start courting new cast to start showing up and tying the movie world together, and young is a big part of what they should be looking for.

Kristopher Tapley: They could certainly use that extra edge. The "X-Men" films have made it a point of balancing older and younger characters, largely due to the story of a school of mutants, of course. But I'm not sure they've done all that great a job delineating along the way. It's ended up being a big gobbledygook of featureless mutants at times. That added texture would be a nice way to add dimension to what Marvel is doing with "The Avengers."

3. Is Johnson on his way to becoming the next Gosling?

Gregory Ellwood: Well, it's up to Johnson. The 22-year-old Brit has the talent and good looks to become a global star, but he's also at times a strange bird. He's always going to have to answer questions about the fact his wife is 25 years older then him. And for many people around the world that's just weird. Then again, James Franco has proven you can be pretty off kilter and still have a burgeoning career.  Plus, Johnson's acting skills may seriously outweigh both Gosling or Franco's.

Drew McWeeny: Gosling is the right comparison. Part of what makes him Gosling is the weirdo personal mythology that he's built up, especially in the last few years. He'll step in to break up a fight wearing Capri pants, because he can! I've seen women react to Taylor-Johnson in the room, and it's damn near chemical. He knows it, too, and yet when he talks about his wife and his family, he lights up. He is hard to get a bead on, uncomfortable with close examination, and he's genuinely talented. He's also still really young. "Anna Karenina" was a step in the right direction, and as long as he mixes it up, he's going to end up with an army of fans.

Kristopher Tapley: He certainly has the right eyes on him to go the Gosling route if he wants to, straddling art house and big budget genre with ease. It's impressive to go from "Nowhere Boy" to "Kick-Ass" to "Anna Karenina" to, assumably, "The Avengers 2," no question about it. It all depends on his personality and what he wants his career to be. I've been slowly coming around to the guy, and kind of like him for the Quicksilver gig. The debate these days is the evolving face of the movie star, with guys like Christian Bale and Channing Tatum working in the studio system and outside of it, so I'd waer a smart road map would be taking cues from these guys.

For more on Johnson's potential casting, click here.