Anyone who pays attention to burgeoning talent in Hollywood has had their eye on Joey King for some time. Though only 19 years old, the Los Angeles native has been working steadily in film and television for 12 years, attracting attention for her preternatural maturity—which allowed her to hold her own opposite acting heavyweights in Season 1 of FX’s Fargo—and her arresting features, which stood out even in the gloomy prison pit of The Dark Knight Rises, where King played a young version of Marion Cotillard’s villainess. But for her latest and most ambitious role yet, in Hulu’s The Act, King had to transform into the real-life figure of Gypsy Rose Blanchard—a teenage girl who was grievously abused by her mother, Dee Dee, and is currently serving time for orchestrating Dee Dee’s murder.

The story of Gypsy Rose and Dee Dee Blanchard is much stranger than fiction. As outlined in the 2017 HBO documentary Mommy Dead and Dearest, as well as Michelle Dean’s in-depth reporting for BuzzFeed, Dee Dee (played on-screen by Patricia Arquette) was engaged in a long-term con job to fake a variety of illnesses for her daughter, in order to benefit both from the sympathy and fiscally lucrative charities that supported Gypsy Rose. The con involved some acting on Gypsy’s part, but Dee Dee also kept her daughter sick using unneeded medication. For this project, King had to tackle almost a triple role—playing the deeply sick girl Gypsy Rose pretended to be, the actually sick girl her mother ensured she’d be, and the healthy girl she dreamed of being. In 2015, Gypsy Rose conspired with Nicholas Godejohn (played by American Vandal breakout Calum Worthy) to kill her mother.

For anyone who has seen footage of the real Gypsy Rose, King’s performance is a chameleonic revelation. In order to take on such a psychologically and physically demanding role, King leaned heavily on her co-star and on-screen mother: Arquette. “When I looked in the mirror after shaving my head,” King told me during a lengthy chat at the Television Critics Association winter press tour last month, “I thought to myself: ‘Holy shit, I’m about to play Gypsy Rose Blanchard for four and a half months of my life. Next to Patricia Arquette. Are you kidding me?’” Here, in her own words, is how King did it.

Vanity Fair: Had you watched the HBO documentary Mommy Dead and Dearest before your audition? You capture Gypsy Rose’s voice so well.

Joey King: When I got the audition, I watched the documentary, and I was so excited and nervous. I wanted it so bad. I was called in twice, and they said both times in their e-mails: ‘Don’t do the voice when you come in. Don’t do the voice.’ So I didn’t do the voice, and I got the role. Then, I called our show-runner and some producers, and said: ‘Y’all, I think I should do the voice. I think it’s a huge part of who she was.’ They never wanted it to seem like we’re making fun, or sensationalizing who Gypsy was, but I’m so thankful that they let me.

It’s pretty uncanny. And I know you listened to tapes of her voice over and over while preparing. Was your preparation process for this role similar to things you’ve done in the past?

I feel I’ve really let go of any ego, vanity, anything I knew or thought I knew about acting, to just really try and dive into this as deeply as I could. There’s a lot of twists [in The Act], and disturbing information revealed in crazy ways. What I love is this show is in no way sensationalizing. It’s a chilling story, and you should feel disturbed while watching it.

Some of the most unsettling footage from Mommy Dead and Dearest features a repentant and vulnerable Gypsy Rose in jail. When I watched it, I genuinely couldn’t tell if she’s being real or if she’s manipulating us, the viewer.

That’s the thing: Gypsy’s a master manipulator. She was raised by one, and now she is one. It’s not her fault, and it’s going to be so hard for her to adapt to normal life . . . I pray for her that she’s able to find someone to talk to when she gets out, and starts to try and adjust to normal life and lead normal relationships.

Did you talk to her at all?

No. We weren’t able to.

Do you wish you could have?

I do. But I am so grateful that Michelle Dean, who reported on the Blanchards, was a producer on the show. I was able to sit down and talk with her for hours about anything. Speaking to Michelle was the next best thing. Now that I’m finished filming, I think that maybe if I had contacted Gypsy, it might not have been a good thing. I just have a feeling.

Gypsy’s father, Rod Blanchard, and his second wife, Kristy Blanchard, are such a key part of the documentary. Do you know how they feel about this adaptation?

I’m not really sure what her family’s feelings are. I just know that Michelle was very close to them, and would talk to them often. They’re aware that the show’s happening. I think that we told the story in the most sympathetic way we could toward Gypsy, while still remaining truthful. We did take some creative liberties, but I feel like if someone who’s watching is not sympathetic toward Gypsy, they’re gonna really rethink that when they watch this story. I hope that she and her family are pleased.

One of the most fascinating elements of this story is the role social media, the Internet, and FOMO play in enhancing Gypsy’s frustration as she gets older. In that first episode, once she gets her hands on a laptop, she starts seeing what an ideal relationship is, what a best friend is, what a boyfriend is—all these images really driving home what she’s been missing. There are also fantasy sequences later in the season. What was it like adding that fantastical element to this true story?

When she first got a hold of the computer, you can see in her eyes and her heart she doesn’t even really know what she’s doing. I think seeing her relationship with Nick and the Internet become more and more sinister as the series goes on is such an interesting arc. You go from this girl who doesn’t really know what she’s doing—and then she gets real good at it. She can type really fast now. She can video-chat people.

And because, as you say, Gypsy is such a hard person to know, how do you make decisions about what’s going on with her internally throughout this story?

Every time that she’s around Dee Dee, there’s a sense of performance—to manipulate her mom so that she thinks she’s this sweet little baby. When Dee Dee’s not there and Gypsy’s completely alone, you start to see that she’s becoming self-aware. In her moments of being alone is when we see the arc of sexuality really come to life.

What was the hardest thing for you to get through in this shoot?

I had a lot of firsts on this. I had to disrobe a lot. I had to play into a sexual fantasy world. Calum Worthy and I had so many things to do together that were just really hard. I’m really proud of the way everyone made me feel—female or male director on those scenes. I felt always very supported and taken care of. It was really lovely.

You shaved your hair and wore fake teeth, but what about the physicality of Gypsy in the chair? You’re playing someone who is not disabled, pretending to be disabled.

It was so crazy watching her home videos. When she knows there’s a camera on her, or when she’s in a big public situation, she kinda stares at things with her mouth open in child-like wonder. The way that she would move her limbs and her head when being presented as a disabled child versus when it was just her and her mom on the video camera—her mannerisms were so controlled by Dee Dee, too. So making sure that I had a different type of movement near Dee Dee versus when I was alone was also quite important to me, too.

What were some of the challenges you faced while tackling some of the horrible things that Gypsy did?

Playing it with sympathy . . . Whether she’s lying or not, I genuinely feel the love for her mother that she still has. She even said: ‘My mom would have been a [perfect] mom to someone who was actually sick.’ I was like: honey. Maybe there really isn’t a villain. I think that Dee Dee did what she did because she justified it in her head, and Gypsy did what she did because she justified it in hers.

The mother-daughter bond between Dee Dee and Gypsy is so toxic. How was your working relationship with Patricia?

Every job I do, people are always like, “Oh, did you learn something from working with this person?” A lot of times, I’m like, “Not really.” But Patricia—I do truly believe that people have multiple soul mates in their life, and I believe Patricia’s one of mine. There was a crazy scene in Episode 4, where she and I would just sit there hugging each other, crying beforehand. It was so intense, so emotional, that after the scene was over, I would need to sit next to her and hold her hand and just breathe through it with her. I never felt alone. We have a lifelong bond, because this was such an intense role for both of us.

We wrapped at 2 A.M. one night, and I had started to get sick. Patricia comes in the next day, and she’s holding a huge pot of soup that she made for me at 4 A.M. the night before. She’s like: “O.K., you’re drinking this all day. Then, after work, I’m gonna send you to go get an IV treatment.” Then, she takes this needle, like a sewing needle, out of her bag: “O.K., I read this online. If I prick your pointer finger right next to your nail and draw blood, it’s supposed to get rid of sore throats. It’s a Chinese medicine practice.” She soaks the needle in alcohol, and she pokes my finger. I’m like, “Fuck. Ow.” It didn’t bleed. She poked me like three times, and I was like, “O.K., I think it’s not working.” If it had been me, or if it had been our prop master that was sick, she would have done the same thing. She’s just such a good person.

How are you feeling now?

I’m so excited, and I’m so nervous—so nervous. I feel very vulnerable. Every time I express nerves or self-consciousness like this, Patricia’s always like: “Cut that shit out. You’re awesome.”