In the end, WandaVision was about so much more than Wanda and Vision — both thematically, and literally.
Seriously, consider the sprawling cast, including but not limited to Kathryn Hahn’s Agatha Harkness, also known as "Agnes.” Rounding out the classic sitcom cast are Tommy and Billy, adorable twins who added the family factor. By the end of the show, it seemed like none of these characters would return, especially the twins.
Enter: the post-credits scene.
Billy and Tommy are still out there, somehow — and the comic books not only pave a way for them to return, but to return alongside Agatha. Here’s how it could happen, and why it needs to happen.
How Tommy and Billy could return to the MCU
In WandaVision, the Maximoff-Vision boys were disintegrated as Wanda lifted the Hex from Westview. In the comics, this is roughly analogous to how Mephisto absorbed the boys into his being as they were from the start manifestations of his power. But that wasn't the last we saw of the twins in the comics.
Years later, Billy Kaplan and Tommy Shepherd, born and raised in different families, both discovered they had superpowers. Billy joined the Young Avengers, and together they rescued Tommy from a juvenile detention facility for superpowered teens. Immediately, it was obvious they were somehow related. These versions of Billy and Tommy, born to completely different families, were reincarnated versions of the boys Wanda and Vision lost.
There are apparently no rules when it comes to Chaos Magic, so while the twins we saw on screen may be gone for good, we could see two Young Avengers in a later MCU property who bear a strong resemblance to them. After all, we heard their voices when Wanda was shown reading the Darkhold; there's no way they're gone forever.
Though it may seem like their immediate purpose in the MCU is at an end, in the comics the twins provide some much needed representation. Billy, aka Wiccan, is canonically gay and Tommy, aka Speed, is canonically bisexual. Plus, they could bring the entire franchise to a whole new generation. These boys are now Marvel's ace up their sleeve, and it's just a matter of time before they use it.
How Agatha Harkness could return to the MCU
Agatha's fate isn't as grim as the twins — she at least is for sure still alive, just trapped in an ultra-sanitized suburban lady's body in Westview.
While Agatha wreaked havoc over Wanda in WandaVision, her role in the comics was always that of a tutor, someone who could coach Wanda through the use of her powers and provide help when the Chaos Magic got too overwhelming. Currently, Wanda's only form of mentorship is through the Darkhold, which, considering Agatha calls it the "Book of the Damned," may not be the best choice.
Wanda left Agatha with some telling final words: "I know where to find you.” Perhaps in the future Wanda will release Agatha on the condition she gives up use of her powers and solely focuses on training Wanda.
While WandaVision's Agatha Harkness hasn't been the most faithful adaptation from the comics, there are all sorts of potential ways here to give Wanda what she most needs right now, and what she used Agnes for in her fantasy: a friend to listen to her sorrows and help her with her harebrained schemes. Ideally, she wouldn't be a secretly evil witch plotting to steal her powers, but hey, there's always room for character growth.