Warning: if you haven't seen the finale episode of WandaVision, this post contains MAJOR SPOILERS so read at your own risk!
WandaVisionfans have been intrigued by Agatha Harkness' "husband" Ralph she has been mentioning since Episode 1. Unsurprisingly, the true identity of the said mystery character has been the subject of several theories and rumors that have circulated all over the internet the last couple of weeks.
One persistent theory suggests that Ralph could actually be Mephisto and given the fact that Maximoff shares a lot of history with the said Marvel villain in the comics, the entire "Ralph is Mephisto" argument is actually pretty plausible. Other theories suggest that he could end up becoming Nightmare which isn't too farfetched as well since he's rumored to be the main villain of Doctor Strange in the Multiverse of Madness.
Now, after weeks of speculation, Episode 9 finally reveals who "Ralph" actually is and we can confirm right off the bat that it's not either Mephisto or Nightmare. In a stunning turn of events, Evan Peters' "Fietro" is revealed to be in fact Ralph and to those theorizing that he's the same exact Quicksilver from the X-Men films, we've got some bad news for you as the finale pretty much debunks that.
In the finale, Monica Rambeau herself uncovers the truth behind fake Pietro, and apparently, just like everyone else in Westview, he's an actual citizen who is under Agatha's spell. We later find out that his real name is Ralph Bohner and he's being controlled by Harkness with the help of a magical necklace.
It's worth noting that Agatha previously said that she didn't have anything to do with the character who was cast as "Pietro Maximoff" in Wanda's pocket reality but as it turns out, the evil witch lied and just like her viral theme song suggests, it's truly been Agatha all along. The real question is, why did she choose Ralph out of all the people in Westview to mess with Wanda's emotions? It could've certainly been anyone else, right?