Brigette Lundy-Paine. Photo: Getty Images

It’s no surprise why Brigette Lundy-Paine broke out as a fan favorite on Atypical’s first season: As the younger sister of an autistic teenage boy, her character Casey was his outspoken, fiercest protector — all while their sibling relationship played out realistically with the right amounts of sparring, hand-holding, and humor.

Lundy-Paine, 24, is still a relative newcomer to Hollywood. Her first major role was in 2016’s Margot vs. Lily, an online series created by Nike, and last year she appeared in The Glass Castle with Woody Harrelson, Naomi Watts, and Brie Larson. “I’d been reading scripts for two or three years before I got the script for Atypical,” she told Vulture during a phone interview. “And when I read Casey, I felt I had been looking for her. I felt like I had been, whether it was the right choice or not, playing every audition as Casey.”

In the first season of Atypical, Casey’s story revolved around supporting her big brother Sam (Keir Gilchrist), but in the show’s sophomore outing, she grows into a more developed character who goes through trials and tribulations at her new private school, navigating life with her estranged parents while exploring romantic relationships of her own. Lundy-Paine spoke to Vulture about Casey’s evolution, what she’s learned about autism from the show, and that fun “switch-boom” dance in the ninth episode.

This season, the show expands a lot beyond Sam’s experience, especially for Casey. How do you feel about her growth?

In season one, you see Casey as more of a peripheral character to Sam’s world. This season just goes deeper into what she’s really like and what she’s like when her parents aren’t around — and because we have so much of Casey in a new environment this season, you really get to see how she handles it when she’s not on top. From what we saw in season one, she’s a strong, feisty character who never says the wrong thing and is always a leader among her troop. I love her journey this season because it takes her to the point of growth where teenager start to surprise themselves.

Do you enjoy reliving adolescence?

I love it. [Laughs.] I love it so much because Casey is much more grounded than I was when I was her age. It’s so funny to be in your 20s and look back at your youth and think, Oh my God, all that I didn’t know. All that I could have known, but there was no way to. In a way, it’s a double-edged sword because I have to let Casey live out her youth with just as much surprise. It’s such a pleasure to see where [Atypical creator Robia Rashid] takes the story and see where Casey takes me emotionally. Mostly, it’s just fun to mess around on set. My whole life, I always wanted to be a Disney Channel kid. I’m like, Thank God, I wasn’t. But it’s so fun to be 15 on set and mess around with the sound guy and go and steal candy from video village. [Laughs.]

Let’s break down the different aspects of her story. Casey and her mother Elsa weren’t particularly close in season one, and now Casey is very angry and disrespectful towards her. How did you feel about that?

In season one, their relationship is founded on the fact that Elsa has always been more invested in Sam’s well-being, from Casey’s perspective. She’s never really gotten to know Casey. And I think Casey’s relationship with [her father] Doug is so much stronger because he spends the time. Casey just feels in general betrayal from Elsa. When she finds that she’s been cheating on not only Doug, but also the family, all of that betrayal is confirmed and comes to this boiling point. It is an unforgivable act in Casey’s eyes. The fact that she cheated, and then the fact that it drove Casey to write this note that prompted her father to leave, I think Casey feels incredible guilt about that and channels it all towards anger toward her mother.

Then there’s a sweet, hopeful moment in the finale between them.

There’s such a sweet ending, and it’s a teensy little thing. But there are so many moments, I think, Casey does lean on her mom because she is going through this new experience: When her mom buys her new shoes after she’s been bullied at school. Or when Casey acts like she hates it, but Elsa sits down and opens her heart and tells her, “I was with a woman once.” It’s a ridiculous scene. You can tell Casey just wants to be anywhere but there, but I think she recognizes how much she’s trying.

Speaking of, the Casey-Izzie storyline went into a really interesting direction. At first, it just seemed like Izzie was a bully. Then it turned to friendship, and now maybe even more. Were you surprised by that?

I think Casey’s incredibly confused. She’s just turned 16. She’s very focused on school — she didn’t even want a boyfriend. But I think that her friendship with Izzie has awoken something in her. She’s been put so much out of her comfort zone that she’s able to feel these new feelings without judgment. I think it’s terrifying her, but she does feel something so intense for Izzie. I hope that it goes on in season three. She’s been awoken, as we might say, to her young queer youth. I don’t even think she’s thinking like, Oh my God, I’m gay. I think she’s like, This is really different and something about this makes me feel whole.

You definitely get the sense that it’s deep.

I’m so glad that it wasn’t written like a hookup or something. It really is just this gentle moment of them being alone together and holding hands.

At the same time, you know she really cares for Evan, too. I’m thinking of your great scene with Graham Rogers in the pizzeria, where Casey hurts Evan’s feelings.

I think she loves him. They have such a good relationship. Her two worlds are pulling against each other.

Casey’s relationship with Sam is one of the best parts of the show. What were some of your favorite moments together this season?

I love any scene with Sam, because first of all, it’s so fun to work with Keir. And second of all, I have a little brother, so I am very familiar with the gentle, tender, well-meaning bullying that comes with being a sibling. There’s such an unbreakable bond between the two of them. It can switch in a minute, where they turn on each other with such love but pure anger. I think it’s just so fun to play the complexity of that relationship. They’ll always be there for each other, but this season, Casey gets to see that it’s a two-way street. Sam really will always be there for her and she doesn’t need to break her back taking care of him the way that she thought.

It’s a perfect portrayal of the sibling relationship, from resentment to love in the space of seconds. But there was a lot of humor, too. She sat on him like an egg!

Oh my God, I loved that so much. I’ll read things in the script sometimes, and be like … Okay. [Laughs.]

What did the script say?

It was, “Casey sits on him like an egg.” [Laughs.] And I was like, I don’t know how else I would interpret this.

The birthday rituals that Sam has for Casey were a sweet touch, but they were funny, too.

Oh. My. God. So good! All of those are pulled from real moments, like real rituals the writers and the creators have from their past. Like the switch-boom! Robia made up that dance when she was little. Her husband is on the writing team and they were the first ones to show me the dance. It was the moment I knew they were made for each other. They switch-boomed in front of me to show me what it looked like. It’s so charming.

Did you have any experience in your personal life with autism before doing the show?

My mom was a special-needs teacher for many years, so I knew her students. And one of my best friends from when I was growing up is a teacher for kids with autism now. But it was only recently that I was able to chill with some people with autism who were in their 20s and 30s. And I feel so lucky. We were able to go to the Autism Film Festival about six months ago — there was a panel — and then afterwards we just got to chill and talk with all these filmmakers with autism. It’s such a supportive and and beautiful community. I hope we’re able to do them justice.

What have you learned about autism from working on the show?

I’ve learned that it comes in so many different shapes and sizes, and that communities with autism are extremely supportive of one another. They’re very tight communities and a lot of the stereotypes that have been hammered into our heads are wrong — the mathematical young man, for example. Of course, Sam is male and some people had their issues with a show that was centered around a man. This season, we’ve opened it up. There’s a support group of all these different young actors with autism who were able to show their voice and story on the show.

Sam’s support group added so much to the season. Were they professional actors?

Most people think that it would be hard to be on a set or act for people with autism. But when you think about it, most people with autism use a script in their daily life to communicate in social situations, like at a restaurant, or you know, with a day-to-day conversation. So, it’s actually super easy for the actors that we worked with to work with a script in that way. The casting team sent out a wide call, which actually got hacked on Reddit. They got like 75 emails a day from actors with autism who were vying for these roles. And the ones they found had done theater in school or worked with local theater companies, mostly in Los Angeles. They’re really good actors.

What are your wishes for Casey in the next season? They can’t just leave things the way they are. There has to be a new season!

I know! [Laughs.] I hope they take next season to give Casey a chance to explore her sexuality and coming into adulthood. I’m queer, and I feel that for a lot of queer youth, there’s not a lot of nuanced examples of queerness on TV when it comes to teenagers. A lot of the time, someone will come out as gay and it’s about the coming-out story and then they’re gay. We have such an opportunity with Casey to be really gentle with that story and to give the characters a chance to figure it out and flail. The whole crux of her relationship with her mom is the fact that her mom cheated on her dad. For Casey, I’m sure that haunts her. She’s feeling emotions for someone else while she’s in this relationship, so I’d be interested to see how she’s going to navigate this thing being just like her mother. It’s going to be messy. But I think in the end, it’s going to be really beautiful.