During all the past episodes of WandaVision, fans have been busy trying to find clues that point at the impending arrival of the X-Men or the Fantastic Four. But in all this, what you possibly missed are the hidden hints (yes, plural) in the recent episode that tease what Monica Rambeau eventually becomes in the comics- the superhero, Photon.
The end of MCU Phase 3 was marked by us bidding farewell to three superheroes- Iron Man, Black Widow, and Captain America. As it is high time that more superheroes enter the scene for Phase 4, the MCU is all set to bring them in and looks like they are starting with Monica Rambeau's transition into the superhero Photon, if the hints hidden in the recently released Episode 4 of WandaVision are anything to go by.
The more obvious tease, which can be easily caught by comics fans, is the fact that Maria Rambeau, Monica's mother, went by the moniker "Photon," as seen on the board under her photograph at the S.W.O.R.D. base. Now the name "Photon" has been teased since Captain Marvel where we learn that it was Maria's call sign which she used for herself while working for the United States Air Force.
While in the comics Monica assumed the name of Photon, after she relinquished the title of "Captain Marvel" to Genis-Vell who was the son of the original Captain Marvel, in the MCU it's highly probable that she will take on the name in her mother's memory once she acquires her superpowers (more on that later.)
Now the next two hints could be considered a bit far-fetched but going by how Marvel Studios never portrays anything as a coincidence and is more likely to pitch a detail with an ulterior motive, they are probably more important than you think they are.
For starters, when Monica enters S.W.O.R.D., three big TV screens are airing news about people reuniting after five years now that those blipped away are miraculously back. Notice how there are three channels on the different screens- WHIH, CNN, and Spectrum News. Oh, yes, we know that Spectrum News is a news channel in New York City, but it is a weird coincidence that the screen airing it was chosen as the background when Monica enters. In the comics, there are a number of names that Monica's superhero-alter-ego goes by, like Photon, Captain Marvel, The Lady of Light, Pulsar, and...Spectrum.
Same goes for the analyser Darcy Lewis uses in a later scene to check the radiation in the energy field enveloping Westview. In the scene, she is seen using a "Spectrum" analyzer- of all the names that could be used, why would the show writers use this, especially as soon after this we get to see exactly what could possibly turn "boss lady" Monica into a superhero.
In the comics, Monica turned into Photon when she was bombarded with extra-dimensional energy while trying to prevent the creation of a dangerous weapon. In WandaVision she does get exposed to the same kind of energy when Wanda forcefully expels her from Westview using her powers and, in a way, Monica was indeed trying to stop the creation of a dangerous weapon, i.e., Wanda (whether she is herself going off her rocker or someone is manipulating her to use her powers).
Our money is on Monica manifesting powers from hereon but whether that will come into play in the current attempts of S.W.O.R.D. to break the pseudo-reality (Photon does possess the ability to phase through certain energy fields in the comics) or they will be discovered when all this is over is left to be seen. The latest episodes of WandaVision are currently streaming on the official Disney+ app.