When Marvel Studios and Sony Pictures announced a deal to bring Spider-Man to the Marvel Cinematic Universe, fans were justifiably excited, while also wondering how the deal would work out in practice. Two-and-a-half years later, the deal appears to have been a huge success, with Peter Parker stealing the show in "Captain America: Civil War," and "Spider-Man: Homecoming" set to debut in less than a month. The deal has also freed up Sony to focus on other Marvel characters it controls, with Venom and Black Cat and Silver Sable set to star in upcoming films.

RELATED: Silver Sable/Black Cat Spider-Man Film Lands Title, Director & Release Date

With Marvel and Sony able to make peace, people once again began wondering if a Marvel/Fox deal might be possible to bring the Fantastic Four to the MCU.

The short answer? Don't hold your breath. It's not likely until at least 2022, if even then.

To explain why, though, we need to start with the strange story of how Fox inherited the Fantastic Four rights in the first place.

How Did Fox Get the Rights to the Fantastic Four?

1990's unofficial Fantastic Four cast

The story of just how Fox got the Fantastic Four rights in the first place is extraordinary in and of itself. Fox did not initially buy the rights from Marvel, instead effectively inheriting them from the German production company Constantin Film, which has held them since 1986.

In the 1970s and '80s, Marvel made a big push to sell its properties to Hollywood. The effort was initially quite successful, leading to the "Incredible Hulk" and "Amazing Spider-Man" TV series in the 1970s, as well as the "Howard the Duck" (1986), "Punisher" (1989), and "Captain America" (1990) films. A number of other major franchises were optioned by studios, including the Fantastic Four, which was optioned by Constantin Film in 1986 for an estimated $250,000.

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Under the terms of the option, rights would revert to Marvel unless Constantin began production on a film by December 31, 1992. But, Constantin could not figure out how to make the film—which would need to star four superheroes with four very different power sets—with a reasonable budget. Instead, the film languished in development hell. With the contract set to expire, Constantin asked for an extension from Marvel, but Marvel refused; Batman and Batman Returns had proven the market for superhero films was much larger than Marvel believed when it signed the deal six years earlier.

Desperate to keep the option, in September 1992, Constantin approached B-movie maven Roger Corman to start production on a Fantastic Four film before the year was out, for a budget of approximately $1 million. Corman agreed, and on December 28, 1992—a mere three days before the option expired—filming began on "The Fantastic Four."

There was just one problem: aside from Corman, the cast, and crew, no one really wanted the movie to be released. The film was tentatively scheduled for a 1994 premiere at the Mall of America, but then quietly disappeared into the vaults, killed by Constantin and Marvel. (The full, truly fantastic, story is told in the documentary "Doomed: The Untold Story of Roger Corman's 'The Fantastic Four.'") But while the film never (officially) saw the light of day, Constantin's gambit had paid off; it now had the Fantastic Four rights for another seven years, through the end of the millennium.

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Unsurprisingly, Constantin still didn't have a Fantastic Four film in production by 1999, but it had in the intervening years teamed up with 20th Century Fox, which at the time had a strong relationship with Marvel through the X-Men franchise. In early 1999, Constantin and Fox approached Marvel to extend the option once more, and Marvel—still weak from its mid-90s bankruptcy—agreed to an extension of at least two years.

Production on the 2005 Tim Story-directed "Fantastic Four" (starring Jessica Alba, Chris Evans, Michael Chiklis, and Ioan Gruffudd) did not actually begin until 2004, meaning the contract was possibly extended at least one more time. It appears, however, that the deal has not been renegotiated since about 2002 at the latest. The contract as it stands appears to give Fox and Constantin a perpetual right to make Fantastic Four movies, expiring only if more than seven years elapses without active production on a new film.

RELATED: Mads Mikkelsen Walked Out of His Fantastic Four Audition

This seven year window was likely the deciding factor behind the 2015 Josh Trask-directed "Fantastic Four" reboot starring Kate Mara, Michael B. Jordan, Toby Kebbell and Miles Teller. Fox/Constantin had to start filming something by the end of 2014 (seven years after "Fantastic Four: Rise of the Silver Surfer"), or rights would revert to Marvel. The result was not pretty, to say the least. Counting from that film's 2015 release, Fox/Constantin would appear to have until the end of 2022 to beginning filming a new Fantastic Four movie.

But Who Actually Owns the Rights -- Fox or Constantin Film?

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While it is clear that Fox and Constantin collectively control the cinematic rights to the Fantastic Four, it is not actually clear how they're divided between the two companies. Constantin has produced all four Fantastic Four films, while Fox has distributed all three that have had cinematic releases. Things are further complicated by the fact that we are really talking about two sets of rights: production rights, which let someone make a movie, and distribution rights, which allow them to distribute the completed film to theaters.

Although there are a number of possibilities, the most likely situation is that Constantin retains the production rights first sold to them in 1986, but that Fox has exclusive distribution rights as part of the 1999 deal with Marvel.

RELATED: Fox Won’t Make Another Fantastic Four Movie Unless It’s ‘100% Right’

Why is this distinction important? Late last year, Constantin's parent company suggested it was considering consolidating its assets to focus on its core market: sports broadcasting. If that were to happen, the Fantastic Four production rights could end up at another studio or production company. Or, they could revert to Marvel.

Of course, even if Marvel somehow reacquired the production rights, that doesn't mean we would see an MCU Fantastic Four film anytime soon. A distribution deal with Universal Studios has effectively prevented Marvel Studios from making another Hulk-centric film, for instance. There's no reason to believe Marvel and Fox would want to work together on the Fantastic Four.

Relations Between Fox and Marvel/Disney

Wolverine Avengers

While Marvel and Fox shared a very close relationship during the 1990s, things have gotten extraordinarily frosty in the past decade. With Marvel Studios bringing production in-house, Marvel changed from a licensor to a competitor.

Things have only chilled since then. In 2012, Marvel's parent company, Disney, acquired Lucasfilm and simultaneously announced it would be producing and self-releasing new "Star Wars" films. "Star Wars," a franchise so associated with Fox that the studio's fanfare was regularly included in the films' soundtracks, was understandably frustrated. Disney had effectively bought the studio's biggest franchise out from under them, with Fox getting nothing to make up for the loss.

RELATED: Doctor Strange Director Wants to See Fantastic Four in MCU

To make matters worse, in 2013 Marvel announced a deal with Netflix that included Daredevil—a property Fox had controlled but let lapse in or about 2010. Rumors since have suggested that Fox will never again let another property revert to Marvel/Disney without getting something in return.

The four years since has seen a near constant barrage of rumors that Marvel is trying to sabotage Fox by downplaying X-Men comics, telling creators assigned to X-Men books that they cannot create original characters (since they would be in Fox's control), and outright cancelling "Fantastic Four" months before the latest movie was released. Whether these rumors are true or merely a series of coincidences, they have increased tensions between Marvel and Fox.

Could We See a Deal Between Fox and Marvel Anyway?

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But while relations between Marvel and Fox are particularly poor at the moment, there is still some remote hope for the Fantastic Four, especially since Fox does not really seem to care about the franchise in and of itself. Instead, Fox's primary concern has been on the X-Men.

RELATED: Why Are All Fantastic Four Movies Doomed?

One possibility that is raised periodically is that Fox might be willing to give up the rights to the Fantastic Four in exchange for something X-Men related. With more and more superhero content moving to television, it's possible we will someday see a swap, with Fox giving up the Fantastic Four in exchange for broader X-Men television rights, which for now have to be negotiated on a case-by-case basis with Marvel. But, as Marvel has increasingly used television as part of the MCU, it may be unwilling to cede any more rights to the lucrative X-Men franchise in exchange for the Fantastic Four. Personally, I don't expect to see this happen anytime soon.

Another possibility is that after running down the clock again, relations between Marvel and Fox could improve enough by 2022 that a joint production deal—akin to the Spider-Man deal with Sony—could be a possibility. With the Fantastic Four being a particularly poor match for the X-Men franchise, there is a high possibility that Fox will have no better idea what to do with the franchise in 2022 than they did in 2015, and might just be willing to take 50% of whatever Marvel does with them as a consolation prize.

That said, Fox has next to zero incentive to strike a deal with Marvel until the current deal nears its expiration. While there is a decent chance the next Fantastic Four movie will be connected to the MCU, it is unlikely to be released before 2022.