Spider-Man: Brand New Day may have been about Peter Parker, but the movie spent a lot of time setting up the rise of mutants in the Marvel Cinematic Universe. Not only does the film feature one of the core members of the X-Men, but it also features an anti-mutant villain as one of its core antagonists.
Fans have seen the MCU introduce mutants in projects like Ms. Marvel and Black Panther: Wakanda Forever. Characters from Fox's X-Men movies have even appeared in Deadpool & Wolverine and Avengers: Doomsday. However, the MCU will finally feature its own version of the X-Men in a movie from Thunderbolts* director Jake Schreier, now scheduled for release in 2028.
With the new X-Men movie just two years away, Spider-Man: Brand New Day has given some clear hints at what the MCU's Mutants Era will look like. Before we break down how the film sets up this saga, be warned that there are MAJOR SPOILERS ahead about Spider-Man: Brand New Day. If you haven't seen the movie yet,

Jean Grey enters the MCU
The biggest, most obvious setup for the Mutant Saga is the introduction of Sadie Sink’s Jean Grey, who is famously one of the core members of the X-Men in the comics. The character starts out in the MCU as a fugitive and a villain who distrusts humans. However, Peter helps her overcome her fear and hatred, sending her down a more redemptive path.
Jean is last seen in the movie sitting on a bus going to parts unknown. Her fate at the end suggests she will eventually end up at Professor X’s school and become part of his team of mutant heroes. How and when this will happen remains to be seen.
Jean likely won't join the X-Men until Avengers: Secret Wars, at the earliest. Sink will reportedly reprise her role as Jean in said movie, according to Deadline. While she could simply be a hero who joins the fight against Doctor Doom, fans could finally see her find her mutant tribe with the MCU's new version of the X-Men.

Metzger may return as a enemy of mutants
Brand New Day presents the head of Damage Control, William Metzger (Tramell Tillman), as a villain who tries to capture Jean so he can control and replicate her mutant powers. By the end of the film, Metzger goes on the run from the authorities, leaving the door open for his return in the MCU.
In Marvel comics, Metzger is a huge anti-mutant activist and an enemy of the X-Men. He could resurface in the MCU as a villain stoking the flames of hate against mutantkind. He could even play a huge role in helping arrest and control more mutants like Jean, ironically thanks to Spider-Man.
In Brand New Day, Peter invents an inhibitor to help him control his evolving superpowers. Metzger spent some time using Peter’s device to control Jean's powers. He could end up replicating the technology later on to create the collars used to shut down mutant powers in the comics. Though Spider-Man invented the device to protect people, he may have inadvertently created a tool used to oppress mutants around the world.
It's unclear what Spider-Man's role in the MCU's Mutants Era will be after Brand New Day. Considering his relationship with Jean and Metzger, the web-slinger could be just as big a presence in this saga as the X-Men themselves. Either way, Spider-Man: Brand New Day played a huge part in helping the X-Men become the new face of the MCU.
Spider-Man: Brand New Day is now playing in theaters.
