‘Stranger Things:’ Here’s How the Duffer Brothers Dealt With the Kids’ Growth Spurts

“They need to not grow while we’re shooting,” Matt Duffer tells TheWrap

They grow up so fast, don’t they?

One of the first things you’ll notice about the new season of “Stranger Things” is that the cast that we’ve grown to love as nerdy pre-teens suddenly look a whole lot older. Mike (Finn Wolfhard), Dustin (Gaten Matarazzo) and Lucas (Caleb McLaughlin) are a little lankier and their voices are a little deeper; Eleven’s (Millie Bobby Brown) hair has grown out; and Steve (Joe Keery) is applying to college (whether or not it will actually happen remains up in the air).

Matt and Ross Duffer, known professionally as the Duffer Brothers, said that they, too, were shocked with their cast’s quick transformation, and it’s only going to continue.

“At first we were, you know, frustrated by — you just want to stop them from growing. But you look at something like ‘Harry Potter,’ and it’s exciting to grow up with these kids, so I think you use it to your advantage,” Ross Duffer told TheWrap when we caught up the brother showrunners on the show’s premiere red carpet at the Bruin Regency Theater in Westwood.

“Still, we were surprised because when we were casting the character of Max, who ends up being a love interest to these kids, we were casting girls that were the right age for Season 1 [but not Season 2]… We didn’t realize they had grown that much and we had to restart the whole casting search and age her up. We don’t have children so it’s shocking to us how fast that they grow.”

I tell them this: They need to not grow while we’re shooting. It’s about six months, so inevitably there’s a little bit that happens,” added Matt Duffer. “The voice changes, the voice gets deeper. Next year Caleb’s going to be driving on set — and I’m not even joking — which is, like, highly disturbing.”

The Duffers also discussed what it was like expanding the show after Season 1’s explosive popularity.

“Well, Season 1 you’re scared that no one’s going to watch it, so at least you have the relief that some people will watch this, but then that comes with expectations,” said Ross, adding that even though most of the “noise” around the show was positive, they tried their best to block it out “and just try to focus on telling something that we were excited about. And then hopefully the fans of Season 1 … would also like this.”

“Once we decided that was our philosophy, that made it a lot less stressful,” said Matt.

The Duffers also offered insight into their favorite ’80s movies, which they very blatantly draw on for inspiration for “Stranger Things.” When asked which ’80’s movie they’d like to find themselves in, they were calculated.

“I mean it would be cool to deal with an extra terrestrial. A friendly one. You gotta be careful what movie you put yourself in,” said Ross.

“You don’t want to be in ‘Jaws,’ you don’t want to be in ‘Alien.’ What about ‘Back to the Future’ though? Because I would love to time travel with Doc,” said Matt. “A lot of the movies we’re referencing, terrible things happen to the people in those movies, so it’d be a little silly to put myself in them.”

You can now stream “Stranger Things” Part 2 on Netflix.