WARNING: The following contains spoilers for WandaVision Episode 6, "All-New Halloween Spooktacular!," now streaming on Disney+.
By the closing minutes of WandaVision's sixth episode, "All-New Halloween Spooktacular!," it's made abundantly clear that the mysterious, sitcom-themed happenings in Westview, New Jersey are being (at least partially) controlled by Scarlet Witch and her powers. After freezing Westview's residents in the wake of Vision's attempted escape and deterioration, Wanda expands the hexagonal-shaped energy field to encompass the entirety of S.W.O.R.D.'s base and agents and transforms them to match her new reality.
It remains to be seen how Wanda's powers have evolved to be able to affect reality, but she certainly seems to have branched out far beyond her pre-existing telepathic and telekinetic abilities. Although her initial powers were directly bestowed upon her by the Mind Stone, a more rational explanation for Westview's reality shifting may actually have to do with another Infinity Stone: the Reality Stone, otherwise known as the Aether.
Wanda's Powers Come From an Infinity Stone
If Wanda now has the ability to bend reality (and possibly even time), then it's possible that her intimate connection with an Infinity Stone could extend to other Stones. Wanda and her brother Pietro had gained their superpowers after being experimented on by Baron von Strucker using the Mind Stone in Loki's Scepter. It could be reasoned that if she received powers from being exposed to an Infinity Stone, then she might be able control or wield the powers of other gems. After all, along with the Westview reality-shifts, Wanda's telekinetic powers seem to mimic the destructive capabilities of the Power Stone, and she has been able to "rewind" time much like the Time Stone is able to do.
WandaVision Has Hinted at the Reality Stone
Throughout WandaVision, there have been numerous aesthetic hints to the Reality Stone's influence. For starters, Wanda's powers have always been portrayed as scarlet energy, matching the red color of the Aether in all its forms. In addition, in the promotional materials for the show, a red-energy line is depicted transforming Wanda and Vision's sitcom personas into their Avenger identities. This is remarkably similar to the visual effect that was used in Avengers: Infinity War whenever Thanos transformed his surroundings. The Mad Titan's utilization of the Stone to transform objects is also similar to the way the field reacts to contact from outsiders.
The static field's abilities and appearance are also reminiscent of its past depiction during the events of Thor: The Dark World. During Jane Foster's initial investigations into the Aether, she discovered portals that disappear objects when coming into contact, and even gets sucked into one herself. Not only does Westview's field glow red like the Aether's energy, but it also acts the same, sucking in objects and individuals, such as Monica Rambeau and her S.W.O.R.D. drone.
The Reality Stone Was Destroyed... We Think
According to Thanos in Avengers: Endgame, he used the Infinity Stones to destroy themselves, and the evidence of another "Snap" energy surge seemed to prove it. However, since the audience did not see this act actually occur, the fate of the Reality Stone is still technically up for debate.
The unique properties and open-ended fate of the Reality Stone poses a number of questions about its current status. Before being revealed as the Reality Infinity Stone, the "Aether" was depicted as a liquid, almost vaporous "ancient force of infinite destruction," and only truly became the Reality Stone when Thanos merged it with his Gauntlet. Malekith once claimed that "the Aether cannot be destroyed." Perhaps Malekith was right -- if Thanos had destroyed the "solid" Reality Stone, then the possibility remains that the liquid form survived and was released back into the galaxy.
A more terrifying possibility remains that the Stone's "destruction" had a devastating effect on the different realities of the multiverse, creating the Westview anomaly. Seeing as how WandaVision reportedly leads directly into Doctor Strange in the Multiverse of Madness, exploring the after-effects of the Reality Stone's destruction could explain Quicksilver's appearance and foreshadow the MCU's future.
Wanda Reformed the Stone
Even if the Reality Stone was destroyed proper, there is a chance that Wanda could have rebuilt it. Evidenced by her ability to destroy the Mind Stone, it has been shown that the energy signature of Wanda's powers can directly manipulate an Infinity Stone to the point of destruction. She was also a witness to Thanos using the Time Stone to rebuild Vision and his Stone. So, if she has the power to destroy a Stone, then perhaps she attempted to reconstruct one from oblivion. This might explain how Vision was resurrected as well, as she would have rebuilt the Stone in order to bring back her deceased lover.
If the Reality Stone still exists in one form or another, then there's also a chance that it's inhabiting Wanda. As explained by Odin in Thor: The Dark World, "[The Aether] seeks out host bodies, drawing strength from their life force." In that film, both Malekith and Jane Foster were hosts, and they were able to wreak havoc with their newfound power. Seeing as how Wanda is most likely a powerful enough being to be able to merge with an Infinity Stone and survive, she could easily be the Reality Stone's new host.
WandaVision May Be Hiding ALL of the Infinity Stones
Countless theories have been posed regarding WandaVision's hexagon imagery. While they could simply be a reference to Wanda's "hex" powers, there are six Infinity Stones and hexagons are a six-sided convergence. This could indicate that Westview has somehow become a convergence point for all six Infinity Stones, with all of their attributes manifested in one being: Wanda.
The powers of most the Stones seem to be present in Westview: the citizens are mind-controlled, the time-period keeps shifting, new souls are created (and old ones seemingly brought back) and the fabric of reality keeps changing. It could even be argued that the field around Westview could be created by the Space Stone to keep everything contained. How the Reality Stone (along with the other five Stones) could still be in existence and why they chose Westview to converge would be a mystery, but if the gems have returned, the multiverse would never be the same post-WandaVision.
Written by Jac Schaeffer and directed by Matt Shakman, WandaVision stars Elizabeth Olsen as Wanda Maximoff/Scarlet Witch, Paul Bettany as Vision, Randall Park as Agent Jimmy Woo, Kat Dennings as Darcy Lewis, Teyonah Parris as Monica Rambeau and Kathryn Hahn as Agnes. New episodes air Fridays on Disney+.