As you've probably gathered from the title of this article, we'll be going into 'Wandavision' spoilers here. So be warned.
Episode five of 'Wandavision' dropped on Disney+ last weekend to big acclaim.
Titled "On a Very Special Episode..." it seemed that elements of the mystery were finally coming together.
Then there was that big surprise twist in the last couple of minutes as .......
Wanda's brother Pietro, aka Quicksilver, arrived at the door.
Only thing was the character wasn't played by Aaron Taylor-Johnson, who played the role in the MCU movie 'Avengers: Age of Ultoron'.
It was Evan Peters in the role, the actor who'd played the superhero in the 'X-Men' reboot movies.
Showrunner and head writer on 'Wandavision' Jac Schaeffer divulged more to marvel.com about how the casting came about.
But be warned, if you're looking for any more clues about the Marvel series, he gives pretty much nothing away.
"We loved the idea of [bringing him back]," Schaeffer said. "And then we were like, how in the world are we going to make this make logical sense?
"Because that's the thing, you can hatch a million great ideas, but to make them land, to make them be grounded, to make them feel organic to the larger story."
He continued: "This show is such a mind scramble, and because it's working on so many levels, and there's so many notions of what's real and what's not, and performance, and casting, and audience, and fandom, and all of that, we just thought it would be the biggest thrill to bring Evan over to the Marvel Cinematic Universe."
As for how they made it work in the show organically, Schaeffer and executive producer Mary Livanos utilised a popular sitcom trope.
He explains: "We had long had the idea of the trope of the brother, or the relative, or whoever comes to town and like, stirs things up with the family — that sitcom trope."
As for the actually casting of Peters, Schaeffer says: "We were rooting for it for so long, and didn't know if it would be possible.
"It was complicated to make happen. Evan was always up for it — like, always, always, always. He is a comic book fan, and a Marvel fan.
"He is always up for the absolute weirdest option. And he's a pleasure — truly a pleasure to work with."
The next episode of 'Wandavision' drops on Disney+ this Friday, February 12.