WARNING: This article contains major spoilers for "Blurred Lines," the latest episode of Supergirl, which aired Sunday on The CW.

In the third episode of Supergirl’s fifth season, “Blurred Lines,” J’onn J’onnz’s brother Malefic connected with Azie Tesfai’s Kelly Olsen by disguising himself as her friend, Pete Andrews, played by none other than Sean Astin. He then manipulated her into unlocking his psychic powers by using the technology she’s developing to help PTSD patients as a psychologist at Obsidian North. After Kelly learned who Pete really was, it seemed she’d developed a mental link to him that allowed her to recognize him no matter what form he shape-shifted into. A power that makes her a threat to Malefic that led the gang to send her, along with her brother James, into hiding.

Tesfai spoke wtih  CBR about working with Sean Astin, Kelly’s new Malefic-identifying powers, the personal connection she shares to Kelly’s work, and what’s ahead for her character.

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CBR: What was it like to work with Sean Astin on this episode?

Azie Tesfai: I mean it was the coolest day of work ever! He is just the nicest guy. He cares so much about the work and the story. [Supergirl’s] his daughter’s favorite show, which is an honor. That’s why he did it… And he’s seen every episode, they started with the pilot and watched the whole thing together. That was their bonding activity. And so he’s just great. He’s such a great human and a great actor and such a great family man. And I got to talk with his daughters a bit. Which was so nice, because we shot everything in a day.

We shot, I think there were 10 or 11 scenes in one full day, so we got to spend a lot of time together, which was incredible. I never had more energy shooting that long of a day than with him because he cared so much…. Our stunts and all that kind of stuff, we were glued to the monitors watching. And at the end of the day we didn’t want to leave and we ended up hanging out and had drinks. I was lucky enough to be the person who got to work with him… We didn’t want him to go. He’s so lovely.

It seemed like Kelly was developing a little bit of a superpower at the end of the episode. Can you tease what that might mean in the future?

Kelly doesn’t quite understand the world [of Supergirl]. She cares about people in this universe, in this world – Alex and James and Kara and Lena and Nia and all of them. But she doesn’t get the scope of it. And I think that in the next episode you’ll see her start to realize what she’s involved in and start to understand that world better.

I think of Kelly as one of us getting dropped into this world. A lot of it doesn’t seem real and you kind of talk yourself out of it. And she gets to understand… how complicated it is.

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What are your feelings about the memory reading tech Kelly is working on this season?

I was excited about it. My mom… worked in mental health and did a lot of things that people weren’t doing in terms of therapy treatment and helping people in a real way. So when [showrunners] Jessica [Queller] and Robert [Rovner] told me that that was where they were going with Kelly I was excited because it was something I had grown up around.... And I think technology is the way. Azie drinks the Obsidian Kool-Aid. And I know it’s an unlikely opinion but there is potential to help people.

You see all these studies now coming out about different things that are helping with PTSD treatments that are unconventional. And so I do think that there are ways that we haven’t explored to help people in a more effective, deep, timely way than how we’re doing it. Mental health still feels a bit archaic in the way that we’re treating various illnesses. So I find that very exciting.

And Jessica and Robert have sent me articles on things that are developing in our world that we are talking about on this show, which is a bit frightening but also exciting if you can help people that have had trauma, especially veterans who have severe PTSD in a society where I personally feel like we’ve discarded and not helped them in the way that we are owed to help them. I think that thought is exciting and I share Kelly’s passion… So I loved it.

Kelly is very open and trusting and the other characters worry about her because of it. How will that play out? Is Kelly going to become more guarded?

It’s who she is. She is open and trusting and kind and empathetic and it’s what I love about her so much and it’s what I think is a big part of who I am. What I admire most about her is that she hasn’t allowed society to shut that down in her. And she’s been through a lot of experiences, you know last season seeing the storyline with her family and her dad and what she’s been through. She hasn’t had the easiest life and she still managed to [stay open]… I know from what we’ve shot she’ll go through a roller-coaster of it but I think she strays to who she is. And there’s such value in that.

The thing I love most about Supergirl is that there is such a comparison [between] what we’re filming and what’s happening in our current society. I think everything in the Supergirl world leads to you not being trusting and hopeful, just as everything in the States right now and the political/social climate leads to that as well. But I think having hope and fighting through things and trying to help people and listen is the solution to all the problems we’re having in society right now as well as what Kelly stands for. So I think she’ll always be true to who she is and I think it’ll be a good reminder for everyone around her that hoping is the way out of darkness.

Last season the dynamic between Kelly and James was so great. At the end of “Blurred Lines” it looked like you were heading off to have your own brother/sister time. Are we going to see more of that sibling dynamic in the next few episodes?

Yes, we will and it was the most fun to film. You will learn a lot more about the Olsens and see a lot of our dynamic, which is really exciting.

Airing Sundays at 9 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen and Chyler Leigh as Alex Danvers.

NEXT: Supergirl: Azie Tesfai On Kelly Olsen - and Why She Didn't Watch the Show