There used to be a time when one blockbuster superhero property was enough to keep fans satisfied, but Marvel changed all that with its Avengers movie universe. With Batman V Superman and even X-Men: Days of Future Past following a similar rule – that merging heroes and brands means bigger business – crossovers between rival studios seems inevitable.

But even if Marvel’s separation of properties across multiple Hollywood studios means that X-Men‘s producer wants a team-up with The Avengers or Fox may be building towards an X-Men/Fantastic Four shared universe, DC Comics is another story. While the two juggernauts may have joined/clashed forces in the past, fans shouldn’t expect DC and Marvel to share the same space anytime soon – especially not on the big screen.

Many cynics these days point to crossovers – whether they be between heroes under a single banner or across corporate lines – as a sign of corporate greed, unless studios “put in time” as Marvel did, establishing standalone heroes before uniting them in a single movie. It appears that DC Comics and Warner Bros. are also looking to create a shared movie universe sooner rather than later, with multiple superhero films slated for release in the coming years.

Once both Marvel and DC get their universes up and running – the two studios with the most known characters to draw upon – then filmgoers, like comic readers before them, will no doubt wonder what would happen if the two joined forces. A world-ending blockbuster with unstoppable potential, some would likely say. And there’s even a precedent set for it in the comics.

The most often cited crossover tends to be the 1996 “DC vs. Marvel” event, essentially pitting the two universes together with only the victor surviving. Long-debated fights between fans were put into action: Aquaman vs. Namor, Flash vs. Quicksilver, even Superman vs. the Hulk. When all was said and done, the two were merged into a single Amalgam universe, meaning that although the event produced some memorable stories and artwork, neither ended up on top.

The comic event – or the later “JLA/Avengers” event of 2003 – may seem like evidence that a movie crossover could happen, with a potential story in place to follow as well. But we would point out that in 1996, the world of comic books was a very different one. Not only did it seem that the medium’s best days were behind it (arguably, that’s still the case), but Marvel Comics was just a few years away from bankruptcy.

In other words: the two rival publishers both had something to gain by meeting fan demand, and were both sorely in need of a boost.

Those times have changed, with Marvel boss Joe Quesada (who helped save the publisher) claiming that the superhero or comic book genres of film aren’t going anywhere. That being said, the world of comic book talent is nowhere near as divided as film; artists and writers move from DC to Marvel to creator-owned properties in pursuit of steady work or more creative freedom. And there are already signs that creative freedom won’t be a top priority for big screen superhero films as shared universes become more and more rigid.

Is it the same case for the comics? When we sat down with writer/artist/creator/DC co-publisher Jim Lee and Marvel artist/writer Brian Michael Bendis at a townhall meeting at SDCC 2014, the question of crossovers was inevitably raised. Both legendary creators have seen the restriction and benefits of the comic book world close up: Lee may be cemented as a DC executive today, but made his start with Marvel before launching his own label and “WildC.A.T.s” series, among others.

As the mind behind “Ultimate Spider-Man,” one of the founding members of Marvel’s “Ultimate” Universe, and writer of the “New Avengers” relaunch, it goes without saying that Bendis has a passion for many Marvel properties, regardless of who owns the movie rights to either. And the pair reiterated that its the creators, artists, and writers who dream of crossovers just as much as their audience. And as fans have come to expect, Bendis spoke quite candidly:

“The last time I was in a room with Jim Lee, we were at LA Comic-Con… [looks to Lee] you came up and whispered in my ear: ‘WildC.A.T.s/Avengers…’ and then you walked away and I haven’t seen you since… But I thought: ‘I’d drop something to do that.’

“See, this is what happens when the creators get together and the whispers start, and then the ideas start running, and then the realities of corporate America stop it right in its tracks.”

It isn’t hard to grasp why corporations would put the brakes on even their own creators’ enthusiasm for cross-company collaboration, as it happens just as often in today’s film industry. An Avengers/Guardians of the Galaxy crossover is already in the works, but even when a producer of Fox’s X-Men universe expresses a clear desire to merge the series with Marvel’s, it’s immediately deemed a long shot (Marvel Studios boss Kevin Feige has said it won’t be happening any time soon).

Still, the upside seems obvious to any optimistic fan: Marvel and DC both enjoy increased attention and sales with universe-wide ‘events,’ even bringing iconic super-teams to blows. While that may be easier when all characters are owned by the same company, Jim Lee offered his opinion on the less obvious challenges, and reminding fans that the main reason companies choose not to combine success is the same for comics as it is in film – they simply don’t have to:

“I think it’s a lot of work, it requires a lot of people working in good faith. I think the big questions is: both companies make a lot of money off their own titles, so what’s in it for them to share that revenue? That’s a big part of it. Obviously it would be huge news, and you would think that the increased sales would make up for that, but then, who’s throwing in what talent to the pool, all that kind of stuff.”

The escalated pressure and workload can’t be understated when crossovers move from the corporate minefield of comics into the realm of blockbuster movies. While Fox’s Mark Millar might long for a world where competing studios compose a single superhero universe, someone has to actually run the project for all involved.

Avengers writer/director Joss Whedon has said he’s not interested in having to write a story with more characters than he has already, and it’s hard to argue that you could do justice to all heroes in such a packed cast – especially when the studio making the film has a clear interest in giving their own properties time in the spotlight.

Bendis – never one to shy away from bold statements – explained another core issue: if Marvel or DC ever actually planned to combine superhero franchises, somebody would have to lose.

“Also, there’s that element where people don’t want to see Marvel and DC beat up Lex Luthor – they want to see Marvel vs. DC. They want to see Thor vs .Superman, and then either Thor or Superman have to get their ass kicked for it to matter. And neither company wants that, you know… ‘It has been stated that Superman is stronger than Thor.’ They don’t want it, neither company would want that. And they’re all billion-dollar characters now, so no one’s interested in making them cooler than the next, so… I get it.

“People want a loser. The reason ‘Civil War’ was successful was somebody lost, and they were shocked: ‘Oh my God, somebody lost!’ You know, they didn’t shake hands at the end and go: ‘Well then, we’ve both seen the light of day.’ You want to see Thor with his foot on Superman’s neck just grinding it in. That’s all they want to see.”

It may seem silly to get hung up on something like ego when movie franchises are on the line, but even the slightest mistake can mean lost millions for movie studios. That being said, comic book movies may end up changing just as much as their source material, so who knows what the future could hold.

Aside from the reasons mentioned above, the difference in tone between the two studios may be the largest hurdle in the end. For now, Zack Snyder is on record as loving Marvel’s brand of superhero movies, and Joss Whedon adores” some of the darker approach. But as we know, the creators aren’t the ones who get to decide if a crossover is in the cards.

It’s safe to say that movie studios won’t agree to share responsibility, share the talent, or share the profits until they absolutely have to. But if they get to that point, it’s anything but good news for fans – regardless of which studio you prefer.

What’s your take on the chances of a DC/Marvel crossover? Is it really a head-to-head fight you would need to make the event worthwhile, or is the difference in tone too much to overcome? Sound off in the comments.

Follow me on Twitter @andrew_dyce.