In "Damage," last week's episode of Supergirl, Morgan Edge found Lena Luthor's Achilles' heel: National City's perception of her. When Edge tricked the people of National City into believing Lena's device had poisoned children, she was forced to confront the idea that she is -- however inadvertently -- as villainous as the rest of her family. During a set visit, Lena actor Katie McGrath addressed how Edge's plot affected her character and how it will continue to impact her moving forward.

"I think this is going to be her Achilles' heel, especially in this season... is that everybody's preconceived notions about her keep coming back and no matter what she does people are quick to blame her because of her last name," she explained. "And so this episode ['Damage'], it's kind of like her trigger. It gets her back up and it puts her into fight mode. You see that very clearly in the episode, that she's like an easy mark because of it. And Morgan Edge manipulates that because he's an asshole."

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"I think Lena holds on to everything. I think that's one of her failings, is that she feels everything and she takes it on and she -- especially anything to do with her family -- she feels extremely guilty that she is a Luthor even though she's never done anything wrong," she continued. "She's very quick to as well believe that she may have done something wrong. Because ultimately I think she feels deep-down that she fears she might be like her brother, her mother, her father. So it's her Achilles heel, as well as her strength. She's very intelligent, she's very capable, she's very strong. She draws both from her family, her name, who she is and has good parts and bad parts, like everything."

McGrath also weighed in on Lena's dynamic with her rival Morgan Edge. "Any pretence of having a nice business relationship has gone out of the window by the time this episode is over," she shared. "With Kara and with all the other people, she's on the same level. But Morgan is somebody within the business world... They're two very similar people. So they can have that kind of interaction and that kind of antagonism. So as this goes on, she's sort of dealing with somebody who's on the same level as her within sort of the professional life. Somebody's who's running their own company and somebody who's as powerful as she is and as capable as she is in those situations. So it's an interesting dynamic in that situation. Also, you've got the fun dynamic of him being a man and her being a woman and her being younger and more capable than him and him not being able to deal with that -- and Adrian [Pasdar] is going to hate that I said that."

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"I think Edge is very savvy and I think Edge knows what buttons to push," she said, adding, "I think it wouldn't matter who it is. I think he's a smart man and knows how to play her. I think she's aware that she's being played but she can't do anything about it. It's like anybody, somebody pushes your weakness, even when you know they're doing it it still hurts. He's just very good at it."

Airing Mondays at 8 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.