Supergirl: Brenda Strong on 'innate conflict' between the Luthor women

Don't expect the Luthors to break bread together in Supergirl's upcoming Thanksgiving-themed episode.

In Monday's installment, evil Cadmus scientist Lillian Luthor (Brenda Strong) puts her plan to eradicate all aliens from Earth in motion. And you can expect her actions to add even more tension to her already-fraught relationship with her daughter Lena (Katie McGrath), who is trying to reform her family's notorious image and to whom Supergirl (Melissa Benoist) turns to for help in the episode.

EW caught with Strong ahead of Monday's episode, "Medusa" to talk about Lillian and Lena's complex relationship, the Danvers family's awkward Thanksgiving dinner, and what Cadmus Labs is doing with Jeremiah Danvers (Dean Cain).

ENTERTAINMENT WEEKLY: Episode 207 ended with Cyborg Superman (David Harewood) going to the Fortress of Solitude to retrieve something called Project Medusa. What is Medusa?
BRENDA STRONG: Medusa plays very strongly in the next episode, which is episode 208, and it's basically a virus. It's one of those exclusive viruses that doesn't touch anyone whose organic material is human. It only attacks anything that is alien, and it's a big one. So, that poses imminent threat to the planet.

How did Lillian and Cyborg Superman know that Superman had the virus?
Well, [probably from] the underground intelligence world…I think she's a scientist, so I'm sure there are things about alien life forms that she's aware of. Obviously, she needed to weaken Supergirl enough so that she could take her blood in order to have the key to unlock what was there and to get ahold of it. I'm sure that was her intention from the very beginning. I'm sure there was some mythology that led up to her knowledge of the Medusa virus and how to get it. I think whenever you have a single-minded purpose — like Lillian Luthor does in eradicating all alien life forms from the planet, because she sees them as an imminent threat to humanity — you'll do anything, and I’m sure she has a lot of people who aren't fans of Superman and Supergirl to aid her in her destruction.

Was it hard to get into the mindset of a character who has so much hate for one part of the population?
Well, I think being a parent sets you up to justify almost anything to protect your child, and I think she really, honestly believes that Lex was wronged and unfairly treated and wrongfully imprisoned because of Superman and his lies that he spread about Lex and the misinterpretation of his intentions. I think, ultimately, she's the big mamma bear that's not only going to wreak havoc on anyone that has mistreated her blood, but also, she has a greater intent: She truly believes that aliens are a threat to humanity and that they become the enemy at any time. They may be acting like they're doing good works, but they have powers that we don't have, and we need to make sure that they're not putting us in a weak position. I think there are two fields of play here — the personal and the global.

Lena wasn't too pleased to see her mother when she showed up at LCorp at the end of episode 205. What's their relationship like?
I think any mother with a daughter can tell you it's complex, but there's the added layer of Lena being adopted, and I think there is definitely a strain because Lena doesn’t feel that she is prioritized and she feels Lex was [her mother's] favorite. I basically come out and admit that in some respects. I think it's a very complex relationship and I think there's a lot of hurt on both ends, because I do believe that they have hurt each other over the years. So, there is a strain [on] their relationship. And I think any mother and daughter will tell you that there is a power struggle within a mother-daughter relationship. So, I think that's definitely at play here, too. Obviously, Lena is very aligned with Supergirl and very much wants her as a friend and wants to change the way the Luthors are perceived in society. I think we're working against different ends entirely, and it's difficult.

Is it fair to say that Lena and Lillian aren't on the same page when it comes to aliens?
I would agree with that. I don't think they are on the same page.

How much does Lena know about her mother's job at Cadmus?
At this point, she doesn't know anything at all. But come "Medusa," she's going to start finding out more about her mother's nefarious mission and that will have an impact on their relationship.

Lena befriending and working with Supergirl is probably another blow to their relationship, right?
Yeah, I think so because it's a mirror of what happened with Superman and Lex. In 207, she basically says, "Superman destroyed my son, and I won't let it happen to my daughter." So, she's very protective of Lena and her relationship, and when she saw the two of them together, I think it was probably was a blow to her. You know, we all interpret reality based on how we see things, and when two people are seeing things from two different perspectives, there's innate conflict and that's what makes great TV. So, I think that's what you're having here: two different missions and two different loyalties within the same construct. I'm one of six kids and not all of us see the world the same way, so that adds for interesting Thanksgivings. Speaking of which, we have a really fun episode coming up with a really fun Thanksgiving meal.

Does that Thanksgiving meal involve Lena and Lillian or are you talking about the Danvers?
Oh, the Danvers. My understanding is that it's really funny because it seems like everyone wants to share their secrets: Alex, played by Chyler Leigh, decides it's time to come out to her mother; Kara is shocked when Eliza [Helen Slater] suggests that Mon-El has feelings for her [because] she doesn't even see that coming; and Winn and James have this huge secret about who Guardian is. Everyone wants to share their secrets, but nobody is allowed to talk because it just becomes a cluster of intent that doesn't really ever come out well. I think it makes for great comedy when you have everyone wanting to share something but nobody gets to share it in a way that they expect to.

In last Monday's episode, Jeremiah decided to stay behind at Cadmus after freeing Kara and Mon-El. What is Cadmus doing to him and why does he choose to stay?
That is definitely the super million dollar question from a lot of fans online. I've noticed they have all sorts of theories about Jeremiah's role in Cadmus: Is he really a prisoner or is he in alliances with me? That's something you're going to have to stay [for] and find out. We don't know, but I have a feeling it's going to be interesting once everybody gets the reveal.