"I came to really love that it was a secret," Linnea Berthelsen tells The Hollywood Reporter about her role in the Netflix series.

[Warning: this story contains full spoilers for season two of Netflix's Stranger Things.]

With its second season, Stranger Things dialed things up from Eleven (Millie Bobby Brown) by bringing in a lower number: eight, or Kali, if you prefer.

Played by Danish actress Linnea Berthelsen, Kali is the first main character we see in season two of the Duffer Brothers drama, introduced in the midst of fleeing from the scene of a crime. Kali and her crew of misfits escape police custody thanks to the use of her Eleven-esque powers: the ability to invent illusions, whether that's something as massive as an impromptu fortress wall or something as small and beautiful as a shimmering series of lights.

Following the season's first scene, Kali remains absent until "Chapter Seven: The Lost Girl," in which she connects with Eleven in Chicago. The divisive episode sees Kali showing Eleven how to be more confident with her powers, which they then use to seek vengeance on members of the Hawkins Lab group responsible for their tumultuous childhoods. Eventually, Eleven senses that her friends are in danger back home in Hawkins, and she leaves Kali once more.

What's next for Eleven's lost sister? It's too early to say. For now, here's what Berthelsen tells The Hollywood Reporter about signing on to Stranger Things as Kali, why she feels so connected to the character, the secrecy surrounding the role, her hopes for season three and more.

A week ago, your role on Stranger Things was shrouded in secrecy. Now you're fully in the light. How has that been?

Quite overwhelming. (Laughs) I didn't really read a lot of reviews, to be honest. I knew what I was doing [on the show]. I was very focused on my work and the overall success of the show. I can tell that a lot of people liked the part I was in, while other people are still finding it a bit weird.

Was it hard to keep your character a secret?

I came to really love that it was a secret. I thought it was so interesting. I knew it would be better for the show as a secret. A year ago, it was a little difficult to not be able to reveal to people what I was doing. But I came to really like it once we started shooting.

What's your Stranger Things origin story? Were you a fan before you auditioned?

It was still very new last year when I signed on to the project. I think it was October last year. I'm from Copenhagen in Denmark, and I didn't watch the show right after it came out. I said to my boyfriend that I wanted to watch it when I came to meet him in San Francisco. That's the same week I got the audition. I got the audition, and then we ended up watching the whole season.

How was that experience, bingeing Stranger Things while knowing you might have a role to play in this world?

It was quite incredible! I got these scenes that were so different from the first season. They had nothing to do with the plot from season one. While I was trying to find out what I was going to be involved in, I was really just excited about the rest of the characters. But I was searching for clues about my part.

What did you know about Kali during the audition process?

It was only a breakdown and three scenes. It didn't have any of the characters' names on it. It only had four lines about her: "She's emotionally damaged, she has a hard time connecting with other people, she suffered a great loss as a child, and she's been seeking revenge ever since." That's all I knew. I had to create the character based on this breakdown.

Early on, this role was described in wide-open terms, that it could have been a man or a woman. What do you think the Duffer Brothers saw in you that won you the role? Did you ever discuss it with them?

When we started shooting, I felt I really needed to trust their decision. I didn't really pay much attention to it. I just needed to realize this is what they wanted, and this was how it was going to be. Any part you audition for, you're finding a person and an actor who can respond to the material and bring something different or extraordinary to the text. Sometimes when actors don't get the part, it's not always about an actor being a bad actor; it's about connecting to the material. I really loved this character, and I really connected with it, and I had a very strong vision for it. Hopefully that's what they really liked about it.

What was your vision for Kali? Once you started digging into her, what was it about the core of Kali that resonated within you?

I feel like I've seen parts of her out in society when I've been traveling. I traveled a lot straight out of high school and met a lot of different people all over the world. Even though I didn't know what the end result of the character was going to be, and even though we still don't, I felt like I had so many ideas to bring to the table and make it my own vision — to try to get away from clichés and come up with something that felt true and interesting to me.

What do you admire about her?

She's very determined. She doesn't really care about what other people think. Obviously that's changing in the episode with Eleven. But for the most part, she doesn't really care about other people's opinions. She has a very clear vision for her life and what she believes in. Sometimes I feel like I could learn from that!

Kali can make people see anything she wants them to see. How do you feel that power informs the character, thematically? Is there something here about actualizing the vision?

She can manipulate people. It's about seeing things, and in relation to what happened this season, the problem with a lot of the characters is that they can't see the Shadow Monster. There's some epic thing you can't really see. Kali has the ability to see things and to change it up for people. What she's doing to Eleven is making her doubt her own vision of who she is. I feel like that's a big part of Stranger Things anyway: sometimes you can see things that other people can't.

What do you think Kali sees in Eleven when she comes back into her life?

They knew each other when they were children, and she loved Eleven. She loved Jane. It's reminding her, reminding Kali where she comes from, that this love is very essential to who she was and who she is. She's been running away from that for so many years and turning into this…whatever she is. Is she a sociopath? Whatever she is. I don't want to judge her like that. Something bad happened to her, and Eleven reminds her of all the things she used to be.

You mention not wanting to judge where Kali is coming from. How did you get yourself to a place where you understood her mission of targeting the people who worked at Hawkins Lab?

I needed to go back and realize where all of this was coming from. It wasn't just about killing other people. It's about seeking revenge. Why would I seek revenge? When did that happen in my life, where I feel I need to justify and I need to punish other people? The kids at the lab were suffering. This, as I see it, is Kali's way of responding to that. She was so powerless. She couldn't do anything. She couldn't help Jane. She couldn't help herself. She couldn't help the other kids. Now she's in this position where she feels she can help other people. She can help the children get revenge, if that's what they want. She can help herself by seeking revenge, because she feels that it's the right way to feel.

How do you imagine Kali will fit in with the world of Hawkins, should such a thing come to pass in season three?

My first question is: "Is she ready to do it?" By looking at her in her very last scene in season two, you can tell that she's getting there. The next question: "How is she going to deal with all of these people?" She has a really hard time connecting with other people. She struggled to connect with Jane, but she felt like she had to. Imagining her dealing with Dustin (Gaten Matarazzo) or Steve (Joe Keery)…. (Laughs) It would be interesting.

Who from the Hawkins universe would you most want to see Kali interact with?

I would love to see her dealing with Dustin. (Laughs) It would be so much fun.

Dustin would love Kali. He would have a lot of respect for those powers.

Exactly, and I think that would terrify Kali, that he's not going to be intimidated!

What do you hope to see from Kali next?

There's so much more potential. I have a lot of great ideas. I think we only saw the surface of her. Of course, I'd love to see her going into season three and dealing with a lot of what's going on. But to be honest, I know the Duffers. They're so smart and so brilliant. They're going to do whatever's best for the story. It'll be exciting to see.

Follow THR.com/StrangerThings for continuing season two coverage, including interviews, news and more.