How David Harbour's secret 'Black Widow' set pics helped shape the look of 'Stranger Things' Season 4

Stranger Things notably draws on a lot of classic influences, be it science fiction, horror, or even just D&D. But this latest season also has a more modern inspiration lurking under the surface: the Marvel Cinematic Universe. 

As revealed by series star David Harbour during a recent appearance on Jimmy Kimmel Live! (below), this new season draws from his role in the upcoming MCU film, Black Widow.

Fans last saw now-former Chief Jim Hopper emerge from a Russian prison cell, unbeknownst to the other characters, or his adopted daughter Eleven (Enola Holmes' Millie Bobby Brown), all of whom are now half-way across the world. Meanwhile, his MCU character, Alexei Shostakov (AKA the "Red Guardian"), makes his first appearance in the upcoming film while also in a Russian prison cell. (Though as the trailers for the movie prove, he won't be in there for too long either.) 

"I knew that I was going to be in this Russian prison," Harbour told Kimmel. "And literally a month later, I got a call from Marvel that they wanted me to play a guy who starts out in a Russian prison."

And seeing as how there's nothing the Internet loves more than an unintended Starbucks cup onscreen gaffe or a perfect coincidence, Harbour was more than aware of fans (or the Internet at large) might react. "This is fantastic. I can't wait to see what Twitter and Reddit and all those other guys do with it." 

Well aware of theories people might have about both his characters and the connections they might draw between them — such as Hopper spending his time away becoming a Russian superhero — Harbour took matters into his own hands, ensuring that his performance wouldn't be the only differentiating factor between both roles, but that they would also hopefully look and feel different.

"I had this long hair and this beard and I was big and I thought, 'I can't be the same guy with long hair and a beard in the same prison," he explained. "[So] I was taking pictures of the set unbeknownst to anyone and sending them to the Duffer brothers, making sure they didn't use any of the same colors as the set and making sure the looks were different and the outfits were different."

So his initial look was then tweaked, resulting in the shaved head and trimmed beard fans last saw him sporting. 

"At the end, I had all this hair and all this beard and we had planned to do it that way. And I was like 'guys, we can't do this. I mean, I'm coming out with this Marvel movie, I can't have the beard and the hair," said Harbour of the decision. "So we came up with a whole different look for it."

But while Hopper and the Red Guardian might look different, Harbour's description of Alexei feels like it could apply to both, especially after this last season: "He's a good guy at heart, but he definitely has problems." 

Harbour has previously teased that not only will Hopper return for the next season of Stranger Things, but that Season 4 will finally explore his character's backstory. "[W]e’re going to go into a lot more stuff you don’t know about. It won’t come as a surprise, because it’s been laid in certain ways, but you really don’t understand the depths of it," explains Harbour. "They’ve been putting me off for years and then they gave me these things. I’m like 'Woah, yes, we’re finally going to get into this stuff that we’ve been talking about since day one of the first season.' This stuff is meaty, rich stuff that I’ve always known about him and been dying to talk about, but we haven’t revealed it yet."

Marvel's Black Widow will slide into cinemas on July 9. No release date has been set for Stranger Things Season 4, though it stands to reason we'll (hopefully) see it by the end of the year.