WandaVision is still revolving around the concept of Infinity Stones. Earlier, it was believed that Agatha Harkness could somehow be using the Power Stone. As we’ve seen in every episode on WandaVision so far, those red powers have been directly responsible for changing reality within Westview – just like the scarlet Reality Stone. If you look at how Wanda’s (Elizabeth Olsen) powers manifest, they’re red in nature. As for Agatha’s powers, her powers are in purple. Fans believe that this could resemble the Power Stone. We’ve yet to see Agatha at full power — or even use her skillset for more than a single one-shot — but the post-credits scene could help support the theory even further. When Monica (Teyonah Parris) opens the cellar doors, you can see pulsating purple veins run alongside the mossy branches that are distributed throughout her basement. It’s almost as if, you know, her magic is powering something.
Now people believe that even Monica got her powers from an Infinity Stone. One of the biggest surprises in the Marvel Cinematic Universe’s Captain Marvel was that Carol Danvers was powered by the Tesseract/Space Stone after an explosion doused her in its cosmic energy. As seen with her fight against the Kree dissidents and Thanos later on in Avengers: Endgame, she’s more or less a walking Infinity Stone. Now, in WandaVision, fans are beginning to wonder if Scarlet Witch might be tapping into the Reality Stone and becoming an even bigger powerhouse. It’d make sense given she glows red and is manipulating reality in Westview. However, this series might also have revealed another person powered by one of these gems, and it’s none other than Monica Rambeau.
Many are betting that Wanda, having been experimented on by Hydra with the Mind Stone, was able to harness the Reality Stone to make her utopia come to life. But while that mystery may take longer to crack, the theory surrounding Monica has more clues laid down. A lot of this is due to what’s seen when she goes through the barrier. Her eyes glow blue and when she emerges, she can see the energy spectrum, similar to the comics where an explosion soaked her with extra-dimensional energy, gave her powers and the nickname of Captain Marvel. Seeing as Carol got this treatment in the MCU, it may be that she passed the energy onto Monica in a fascinating turn of events.
This barrier might be the catalyst for her powers fully manifesting and the mystical blue in her eyes could indicate she’s connected to the blue of the Tesseract. In the comics, the gems have possessed people too with Star (an evil Captain Marvel) being host to the Reality Stone, so it could be this stone decided to sink part of its essence into Monica. What also hints strongly at the Tesseract being her battery like Carol are the voices she hears going through the barrier, with her mom, Nick Fury, and Carol all telling her how strong she could be.
To top it off, Monica remembers everything when she gets inside Westview, so clearly, some force is helping her and making her impervious. It comes full-circle when Wanda tries to evict her from Westview once more and Monica pads her epic landing like a superhero with a blue hue around her.