On Tuesday morning, Ryan Reynolds tweeted a photo of his R-rated character Deadpool on a school bus, sporting Mickey Mouse ears.

“Feels like the first day of ‘Pool,'” Reynolds captioned the photo.

Feels like the first day of ‘Pool. pic.twitter.com/QVy8fCxgqr — Ryan Reynolds (@VancityReynolds) March 19, 2019

Less than 18 hours later, Deadpool officially joined the Disney family, along with his fellow mutants in the X-Men and superheroes in the Fantastic Four teams, as part of Disney’s acquisition of 21st Century Fox.

The deal is one of the most dramatic in the current wave of entertainment-industry mergers, shrinking the number of major Hollywood studios to five from six and putting the irreverent Homer Simpson and “Family Guy” in the same stable of cartoon characters as Mickey Mouse and Donald Duck.

There isn’t much chance of Bart Simpson joining The Avengers, but it seems natural now that X-Men, Fantastic Four, and Deadpool will somehow return to the Marvel Cinematic Universe after the film rights were licensed away years ago.

Marvel Studios has built an empire using characters that were once considered B-list, because many of its A-players had been licensed out to other studios, including Fox.

Now for the first time, the studio’s cinematic universe will have access to classic characters that were once key pillars to the publishing division.

Fantastic Four is the comic that launched Marvel, while X-Men was the best-selling and most influential comic title for over two decades.

The injection of new characters comes as Avengers: Endgame will presumably be the swan song for some of the characters who have turned from heroes largely unknown outside of comic book circles to the faces of billion-dollar franchises, such as Chris Evans’ Captain America and Robert Downey Jr.’s Iron Man.

Marvel has just one movie officially dated and titled for after Endgame — July’s Spider-Man: Far From Home, a co-production with Sony Pictures.

Marvel is expected to shoot Black Widow and The Eternals this year, with kung fu hero Shang-Chi likely to bring up the rear.

Also in development are sequels to Black Panther, Doctor Strange and Guardians of the Galaxy Vol. 3.

Unless Marvel Studios president Kevin Feige has a completed script waiting in his desk drawer, any of the newly arrived heroes are unlikely to hit screens at least until 2021, if not later.

Reynolds’ Deadpool may seem at odds with the Disney brand, but CEO Bob Iger confirmed multiple times last year that a popular, R-rated version of the character could exist at the studio.

Before it thinks about rebooting the X-Men, Disney is inheriting two projects from Fox.

Dark Phoenix (June 7) will be the first X-Men movie marketed by the studio and comes from longtime X-Men producer Simon Kinberg, making his directorial debut.

The fate of the other film, writer-director Josh Boone’s New Mutants, remains in the hands of Disney execs, who will decide its future after seeing it.

New Mutants still has an Aug. 2 release date, but is said to be troubled.

The idea of reshoots has been brought up, although the film could ultimately end up on a streaming platform, such as Disney+ or Hulu rather than a theatrical release.

Charting a path forward for the X-Men isn’t the only challenge faced by the integration.

The X-Men films date back to 2000’s X-Men, and there are producer deals that will need to be looked at and either untangled or bought out, say sources.

Lauren Shuler Donner, who championed the 2000 film and has been a producer on all Fox’s mutant-centric movies, is said to have a deal that calls for her to receive an executive producer credit on any X-Men movie whether or not she is actively involved.

Kinberg may have a similar deal.

Marvel Studios has not publicly revealed any plans for integrating members of the X-Men and Fantastic Four into its cinematic universe, though Feige is said to have met with several members of the X-Men old guard in recent months.

While Disney’s release schedule does contain the highest volume of untitled Marvel movies yet (two in 2020, three in 2021), it remains unclear when an X-Men or Fantastic Four movie could make it onto the calendar.

Fargo showrunner Noah Hawley, who was hired to write a Doctor Doom movie in 2017, earlier this month confirmed he’s spoken to Feige about the script centering on the Fantastic Four villain, though Hawley downplayed how serious those discussions were.

Though the Marvel projects will be under the purview of Feige, who has worked on Marvel properties since 2000’s X-Men, genre-based special effect-laden extravaganzas will still be made at Fox.