Stranger Things creators the Duffer Brothers have revealed that the production of IT turned Finn Wolfhard into a foul-mouthed youngster on the set of Stranger Things Season 2. The Duffer Brothers were able to cast amazing young actors that are already branching out and moving on to other projects. So, it came as no surprise when it was announced that Andres Muschietti had cast Finn Wolfhard for his big screen reimagining of Stephen King's IT, but it appears that much like Will in the Upside Down, Wolfhard brought something back with him from his time hanging out with Pennywise the Dancing Clown.

In an interview with Variety, the Duffer Brothers revealed that Wolfhard came back to the set of Stranger Things from the production of IT, but something was different. Matt Duffer explains.

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"He's got a foul mouth. That's the thing... after he (Finn Wolfhard) came back from shooting IT, he did it before we shot season two, he was f-bombing everywhere. And I was like, 'What happened to my innocent Finn Wolfhard?'"

Though we don't know what Will brought back with him from the Upside Down, we do know that it is something far more sinister than Wolfhard coming back cursing at everybody. But as it turns out, Wolfhard has a strong reason behind coming back as a "changed" young man.

In addition to having to spend a bunch of time with Pennywise, Wolfhard's character in IT is a foul-mouthed kid named Richie Tozier, also known as "Trashmouth" for his overuse of bad language. Wolfhard spends much of his time in IT cursing up a storm, so it's no wonder why he came back "corrupted" as Matt Duffer recalls.

Finn Wolfhard is in the middle of having two monstrously successful projects that both take place in the 80s and have crossed over from being horror (Stranger Things is kinda horror) into the mainstream and are both enjoying huge amounts of success currently and that's all about to get a lot bigger when Stranger Things Season 2 returns to Netflix next month. Wolfhard will simultaneously be in one of the biggest television shows and movies at the same time as IT will no doubt gather some more steam when Halloween rolls around.

Andres Muschietti's IT may have been dethroned from the number one spot at the box office this weekend, but the movie continues to do well and has recently become the highest grossing horror movie of all time, beating out The Exorcist and is still raking in good money around the globe. Stranger Things Season 2 is all set to debut on Netflix, starting on October 20th and fans cannot wait. There's no word on whether the Duffer Brothers fully embraced Finn Wolfhard's language that he learned on the set of IT to incorporate into Season 2, but we will find out soon enough when the series is released next month. Now, to figure out exactly what Will brought back from the Upside Down is the next mission.