Ever since the record-annihilating opening weekend of "The Avengers" last year, I've been hearing speculation and questions about whether or not other studios who have the rights to certain Marvel characters would end up trying to strike a deal with Disney and Marvel Studios to include those characters in some sort of cross-over situation that would allow them to appear in a future "Avengers" film.

At the moment, I would not bet on that happening with 20th Century Fox.

This is not a situation where the two different companies are working together to try and create a sense of a larger shared world. In fact, if either of them could get the other to back off, they would. The thing is, Bryan Singer has designed a sequence that he feels only works with Quicksilver, and Joss Whedon feels that there is a pressing reason for Quicksilver to show up in "The Avengers 2," and so what we're going to see is a legally-negotiated stand-off in which we'll get two totally different versions of one character. While they may act like things are amicable in public, HitFix sources say otherwise.

Singer has just cast Evan Peters as Quicksilver for "X-Men: Days Of Future Past." He's shooting first, so presumably, he will win the showdown in terms of being the first to define the character on film. Marvel has larger plans for the character, though, and wants to use him for more than just one action sequence. The way the arrangement works, Marvel Studios cannot refer to the character as a "mutant," and they can't mention Magneto at all. Likewise, Fox can't make any reference to The Avengers in their film.

That means they'll have to either explain his powers in a different way in "The Avengers 2," or they'll just have to make no mention of his origin at all. At this point, there are so many characters in "Days Of Future Past" that it seems odd they'd end up in a pissing match with Marvel about who gets to use a character who, let's face it, 90% of the audience for either franchise has never heard of.

This is the first time this has happened, and there is still time for Fox to blink. If they push forward and allow Singer to include the character, there's a chance they're burning down any future cooperation with Marvel, who have proven themselves to be hard negotiators who aren't afraid to flex whatever muscle they have.

Right now, the rumor is that Saoirse Ronan is in the mix as a possible Scarlet Witch for "The Avengers 2," and there's no word yet on who Marvel will cast as Quicksilver for their film, or even what age range we're talking about. What is obvious is that the battles off-screen are going to be just as interesting as the battles on-screen this time around, and we'll be paying close attention to see how Fox handles things.

"X-Men: Days Of Future Past" will be in theaters July 18, 2014.
"The Avengers 2" is currently set for release on May 1, 2015.