Ruth Bradley, who plays Karen on AMC's HUMANS, talks about teaching a Synth how to act like a human and how Karen is fulfilling her destiny. 

Q: You’ve portrayed a Synth, a Synth who pretends to be human, a Synth who teaches another Synth how to behave like a human…what’s both fun and challenging about going back and forth?

A: [Laughs] It’s great fun. In the first season, I was the only Synth masquerading as a human. While figuring that out, I had lots of ideas about gesticulation and then we created the rules that everyone had a battery life, so how do you pull off being a laid-back human without doing the things you might do if you didn’t have to consider conserving your battery life? Those things were really challenging and interesting in the first season. Those tiny things, like Karen’s hands are in her pockets a lot in the first season. She can move her face a lot more. The second season was really fun because I was masquerading as a human, but Pete knows what Karen is, so it would all depend on who happened to be in the room. And then this season, I’m essentially teaching someone else how to do it. There’s a chunk of dialogue in Episode 1 where she explains how humans move so much because they can’t hide their emotions and they display it in their mannerisms – which is just so true. We’re so readable if people take the time to read us.

Q: How is Karen grieving the loss of Pete this season? Is she allowing herself to feel?

A: A year has passed since the end of the last season and she’s done what I think lots of people do when they’re grieving, which is just put all her efforts into something else. I don’t know that she’s really dealt with how she feels about losing Pete. Sam just woke up at the end of the last season, so I think she’s thrown all her energy into being a mother. We pick up in a place where that is her sole purpose. Sam is picking up on her grief, but I don’t think Karen has grieved. She’s put everything into Sam. In the first season, she was built to be a mother to Leo and wasn’t allowed to fulfill that purpose. Finally, in this tragedy, she’s allowed to fulfill her purpose. In a strange way, I think it feels completely natural and like the thing she was destined to be. She’s the most comfortable she’s ever been when they’re alone at home together because she can be who she was born to be – or made to be.

Q: What was it like working with Billy Jenkins to further develop this relationship between Synth mom and child?

A: He’s brilliant. He’s such a great boy and such a great actor. We had a lot of fun between takes and we would talk about real life, the music he likes and what it was like when I was a kid. We just played and messed around. I was a child actor myself, so I know what worked for me best was when adults treated me like an equal. I very much tried to treat him like another member of the cast. I’m very fond of him. He’s so charismatic and the complete polar opposite to the character he plays. [Laughs] He’s effervescent with energy and jumps around and laughs and sings. I think it helps the relationship because even through our Synth-ness, there needs to be a warmth between Karen and Sam and a naturalness that I hope plays out.

Q: In Episode 3, Karen is unable to even try to save Sam from a potential car crash. How does that weigh on her? Does it echo what she once said about her body not doing what she wants it to?

A: I think that’s Karen’s internal struggle. Just when she thinks she’s found what she needs or wants, her body and her programming just get in the way and she can’t fulfill her purpose. That moment in Episode 3 is deeply heartbreaking for her. There’s another moment where Joe tells her she needs to do something to entertain herself and that doesn’t even occur to her because as long as she can be a mother, that’s all she needs. Eventually, she realizes she can’t do the quintessentially maternal thing, which is to put your child before you. I think it’s the most heartbreaking thing that’s happened to her, aside from Pete dying. It’s a really dark moment.

Q: In Episode 4, Karen decides to give herself up as a Synth in order to save Sam. What does it say about her character? Is it the ultimate sacrifice she can make?

A: She’s really fulfilled her destiny and gone full circle. It’s an awful way to go, but the only alternative would be that he goes too. She manages to follow her instincts, which is another breakthrough in Synths like in the second season when she found out she can cry. It’s another example of that and something that she moves beyond. While we were shooting the first season, I went to a great talk on A.I. with some professors in the U.K. and one of them said that if you did create a completely conscious being, you wouldn’t know how it would evolve. You would lose all control over it because things naturally evolve beyond what you create.  She was not supposed to be able to override those blocks in her system, but she does because she has emotions. It’s love. It’s another mystery of the universe.

Q: What does her death represent in this larger conversation about man versus “machine”?

A: It’s definitely a much more political season this year. Those parallels draw out to real life, which I think is the genius of sci-fi. For me, playing Karen was always about playing the emotion and consciousness that we have as humans, but inside the standards of being a machine. If you were really playing God and creating these things that are so advanced, you couldn’t predict how they would evolve. I think it speaks to stepping back, taking a pause and asking moral questions before technology just runs ahead. We need to pause and ask what it’s all about and what we’re doing.

Q: Now three seasons in, do you find yourself interacting with current technology — Siri, Alexa, etc. — any differently since joining the show?

A: I have an Alexa and sometimes I’m scared, so I unplug it. [Laughs] I notice my iPhone will advertise things that I was speaking about with friends. I’m definitely much more aware. The microphone is constantly on, which is terrifying. Also, fake news – which hadn’t been an issue we were aware of during our first season – and being aware of what kind of news is popping up on your feed and what you click. I think it’s just being mindful.

Read an interview with Tom Goodman-Hill, who plays Joe Hawkins.

HUMANS airs Tuesday at 10/9c. Click here to add a reminder to your calendar.

Watch full episodes of HUMANS on amc.com and AMC apps for mobile, Fire TV, Xbox One, Apple TV, Roku and Chromecast. To get more exclusive interviews with the cast, sign up for the Insiders Club.