Toward the end of Wanda and Agatha’s jaunt down memory lane, viewers witness how Wanda first came to know S.W.O.R.D. and what they were up to with Vision’s corpse. Shortly after returning to life from the Blip, a mourning Wanda marches into S.W.O.R.D.’s headquarters in search of Vision’s remains, hoping to give him a proper burial. She asks and therefore receives, with Director Tyler Hayward (Josh Stamberg) putting the synthezoid’s disassembled body on full display. However, he didn’t just hand Vision over to her, causing Wanda to storm off.
She drives off to Westview, New Jersey, which, at the time, was a normal town with plenty of unassuming residents whom viewers have grown quite familiar with. Wanda arrives at the foundation of a house with the deed to the property she and Vision own, indicating they would’ve built their forever home in that spot. Stricken with grief over what will never be, Wanda releases a huge amount of energy, turning the entire town into a black-and-white, 1950s sitcom set. This is the obvious beginning of Westview’s time under Wanda’s influence, making it clear that she’s responsible for the Hex’s creation.
To make the situation even more shocking, it’s revealed that Wanda never actually stole Vision’s body, as Hayward previously noted. She manifested a version of her own to exist solely within Westview, hence why he couldn’t escape so easily in episode 6, “All-New Halloween Spooktacular!” Since Westview-Vision is technically a creation of Wanda’s imagination, that explains why he’s not only alive and well, but was also devoid of his memories until Darcy’s history lesson.