Although the initial trailer for Doctor Strange in the Multiverse of Madness strongly indicated that the Stephen Strange version of the film was going to be the bigger bad, the Scarlet Witch's presence in the story and the way WandaVision came to a close also implied that Wanda Maximoff might have something to do with the multiverse being shattered into a million pieces. While the latest ad space of the Multiverse of Madness doesn't explicitly explain how reality is undone around Earth's magical heroes, it might explain why by confirming the return of two interesting characters.
Despite Wanda and Strange not spending the most screen time together up to this point, the new trailer establishes that the pair have a lot in common. For example, they both have recurring dreams of (seemingly) other universes to wake up in their home realities, which feel like nightmares. Unlike Strange's Night Terror, which all seem to revolve around apocalyptic scenarios and her love for Christine Palmer, Wanda's dreams are haunted by visions of her twin sons Billy and Tommy, who are still apparently in other dimensions. are present in. The finale of WandaVision made it clear that, even though Wanda was forced to undo the magic that made her sons exist in that particular dimension, they were still somewhere out in the multiverse and had to call upon her. were able to.
The rules of the MCU regarding whether or not people are meant to hang out in other realities have yet to be set in stone. However, this is because a grieving witch trying to get her children back by stealing copies of them from other universes is not the best idea. And it goes against the natural order in a way that can upset some important people.