Shannon Purser may be 21, but somehow, she captures what it feels like to be a teen navigating the complexities of high school pitch perfectly.

The Atlanta, Georgia native got her big break in 2016, when a spooky little show called Stranger Things took Netflix by storm and launched a cultural phenomenon. Spawning a medley of cult favorite characters, from Eleven to Hopper to Dustin, Purser, despite only playing a minor role, somehow rose to the top of the pack thanks to her portrayal of a precocious, acid washed jeans-wearing '80s teen named Barb.

After the beloved Barb was (spoiler alert!) killed off just episodes into Season 1, a hashtag was launched—#JusticeforBarb—and the character became an integral part of the mythos of the series, as well as a marker of its success, earning the actress a Primetime Emmy Award nomination for Outstanding Guest Actress in a Drama Series. It was her first-ever role.

But Barb isn't the only teen Purser has played onscreen: In 2017, she appeared alongside Joey King in the horror film Wish Upon. The same year, she made her debut as Ethel Muggs on The CW's hit teen drama, Riverdale. In early 2018, she starred as a student in a high school drama club on NBC's since-cancelled RISE, and her stint playing fascinating high school girls isn't over yet.

On September 7, Purser, who quit her job working at a local movie theater only two years ago, will make her leading lady debut in the Netflix Original Sierra Burgess Is a Loser. Playing the titular character, she'll star alongside Noah Centineo (yes, of To All the Boys I've Loved Before fame) in a teen comedy film about a girl who, via a text messaging mix-up, gets mistaken by her crush for a pretty, popular girl at her school. (Think Pretty in Pink meets You've Got Mail for the Snapchat generation.)

Ahead of her new film, out next week, we caught up with Purser to talk about taking on her first lead role, working with Troye Sivan, Allie X and Leland on a song for the film, and, of course, Barb's legacy.

First of all: If you were in Sierra's situation in real life and someone had mistaken you for someone else, what would you do?

I would tell them that I was not that person. [Laughs] I think that I would come out and say that they got the wrong number!

It was interesting watching Sierra fall into this hole and keep digging herself deeper, because I think we've all been there.

Definitely! I think the whole movie really does center on the pressure Sierra feels to fit in and be somebody else. Not even just the romance aspect, but she doesn't know what she wants to be when she grows up, and she has this famous father and feels like she can't live up to his standards. She's already feeling super confused and not good enough.

She meets this cute boy, and has that lack of self-esteem, and feels like she couldn't be good enough to be with this guy on her own. Ultimately, she pretends to be something she's not to get closer to him. I think what I really want people to take from the movie is how important it is to be authentic and to love yourself for who you are.

Another theme of the film touches on the expectations we put on people and how we perceive others based on things we think we know or what things look like from the outside. We never really know what people are going through.

I love that all the characters have a lot more to them than what meets the eye. With [mean girl] Veronica specifically, I think both Sierra and Veronica make really bad choices and do some pretty bad things. It's not an excuse, but I do love that you get that window into their lives and understand what leads them to make these choices. The relationship between Sierra and Veronica is really great to me, because I love seeing how they learn they have a lot more in common than they do that's different.

Phones and technology play such a critical role in the movie, shown to be simultaneously destructive and positive. What are your thoughts on the role of technology in our lives today?

Technology is a double-edged sword for sure. You can use it to get in touch with somebody, to get to know somebody, to have really meaningful conversations, or you can use it to hurt and bully people. I think the fact that technology is now in the hands of such young people it's really easy for serious mistakes to be made, you know, when you are maybe a little bit more immature and unsure of how the world works. I think it was really interesting to get to play with that. I hope that everybody who watches it will learn to be more careful and intentional with how they talk to people on social media and how they interact with each other.

What was it like working with Alan Ruck and Lea Thompson? They play your parents in the film and they're both known for their roles in iconic teen movies—Ferris Bueller's Day Off and Back to the Future, respectively.

It was so cool. I was over the moon! Specifically about Alan, because I love Ferris Bueller's Day Off, and I love his character specifically. It was a really an amazing opportunity. He and Lea are both wonderful. They're so fun to work with and obviously so talented. Just watching them act and seeing how comfortable and at ease they were on set was really inspiring and interesting to me. I am very grateful to have gotten to work with them because they're both such kind people and really made me feel validated as an actor—like I deserved to be there, you know?

Were you nervous for your first lead film role?

It definitely was a little intimidating at first. I was so thrilled to have the part, but at the same time, I knew that I was going to be the face of the story and a lot was being asked of me. I was a little bit worried at first. Like, "Can I pull this off? Am I good enough for this part?" I'm just so grateful we had the incredible cast and crew that we did, who made me feel so comfortable. Our director, Ian Samuels, was so wonderful to work with and really made me feel like I deserved to be there. I'm so thankful and I hope that other creators will watch it and see that I can do this, that I can be the lead.

You also sing a song in the film, called "Sunflower," that was co-created by Troye Sivan, Allie X and Leland. It's the first time we've heard you sing, I think. What was that experience like?

I've been singing since I was a little kid, but Sierra was my first time singing on camera, which was definitely intimidating at first. I think it went pretty well. I love to sing. I'm very grateful that the team was so cool, so easy to work with. Leland was amazing. He was guiding me through it and we were playing around with the song. I think it all turned out so beautifully. I think the score and the soundtrack for Sierra really add something special to it.

I heard your high school experience was a bit unusual.

I definitely had a different experience than I guess most high schoolers do. I didn't get to have a prom and we didn't really have a traditional cafeteria. I did go to a private school in elementary school, so I definitely have experience with big crowds of people and having to choose where to sit in lunch, stuff like that.

My high school experience was definitely different. It is interesting getting to play that for the first time in a movie...I think regardless of where you go to school or how your high school experience was, pretty much every high schooler kind of feels the same, you know? That sense of insecurity and learning to make friends.

You've played a couple of different high school roles now: You played a student in Wish Upon, Barb on Stranger Things, Ethel Muggs on Riverdale, and now Sierra, of course. Is there a character that you've connected to the most on a personal level?

That's hard to say. I really connect with all of them. I try to put as much of myself in every character that I play. I don't know, I feel very closely attached to Barb because I was very much playing myself when I was playing her in a lot of ways. I was a teenager when I played her. I was in high school. It felt very natural to me, and that connection was definitely there.

The trailer for Sierra dropped around the same time as the trailer for Insatiable, which was criticized for its insensitive portrayal of fat-shaming. What was your reaction to that?

I think the media in general hasn't been very kind to fat women or fat people. We see so many insensitive portrayals of plus-sized people. That kind of stuff really affected me—not even necessarily the portrayal of fat people, but the absence of fat people. There was never a character that really looked like me that I felt like I could relate to. I think it's just so important to showcase body diversity in TV shows and movies. I hope that Sierra does it the right way. I hope that people watch it and realize that chubby girls are just as worthy of a story as anybody else, and that they can have full and meaningful lives with love and romance just like anybody else. It is important to me that I get to make that narrative a more positive one.

What do you want people to take away after they watch Sierra?

I guess I hope that people watch the movie and feel a little bit braver and more comfortable being themselves and being honest, and that they feel seen and understood. That's my goal with everything that I do.

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