Supergirl type TV Show network The CW genre Superhero Where to watch Close Streaming Options

It’s the beginning of the end for Siobhan Smythe.

When Supergirl returns on Monday, the CBS super series’ new addition will take a step toward fulfilling her comic-book destiny that will eventually transform her from Kara’s rival and CatCo mean girl to full-on villain Silver Banshee (Italia Ricci).

“The evolution itself is actually pretty quick,” Ricci tells EW. “You’re going to know more of Siobhan than you will of Banshee, but you will understand fully how and why she becomes the Banshee and whether or not she chooses to remain the Banshee or change, because she’s able to do that.

“I think they do a really good job with telling that story in a way that keeps her honest and doesn’t paint her as a one-dimensional villain,” Ricci continues. “You can see that there is still a good person somewhere in there; it’s just she’s choosing to put her away for now.”

The evolution really gets thrown into focus on Monday, when Kara (Melissa Benoist) is exposed to red Kryptonite, causing her to act without abandon. “Kara starts it,” Ricci teases. “She does something that is so unlike Kara, and then that makes Siobhan do something equally as classless. Then something else happens where Siobhan is the one that gets in the most trouble for it, and it ruins the most for her. She loses the most out of this rivalry, and so, because of that, she has such a hatred toward Kara and such a fury, and that is what sort of acts as the catalyst to bring out the curse.”

Suffice it to say, the curse may dampen the budding relationship between Siobhan and Winn (Jeremy Jordan). “I don’t think he’s going to feel very good about it,” Jordan says. “We start to see the Silver Banshee come to life in the next few episodes. I do think Winn still wants to find the humanity in Siobhan, no matter what’s happened to her. He’s the only one that can get through to her.”

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Whether he can, however, remains to be seen, but Ricci is hopeful Siobhan can be redeemed. “I think they’ve written her, and you’ll see over these episodes, in such a way that it wouldn’t be unbelievable for her to turn good, and in the comics, she does,” Ricci says. “She ends up best friends and roommates with Supergirl. That being said, I don’t think this is a spoiler, but Banshee never finds out that Kara is Supergirl. So that’s another thing that could be explored maybe later down the line.”

Unfortunately, Siobhan really will tap into her dark side before then, looking to Livewire (Brit Morgan) as an ally in the upcoming Supergirl-The Flash crossover. “It’s so fun because Banshee has the confidence that Siobhan has, but not nearly as much as you need to be a villain,” Ricci teases. “So Livewire takes her under her wing and gives her the boost, and the looks, and the confidence that she needs to really excel as Banshee.”

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Those looks aren’t easy to come by, however. It takes about five hours to to transform into Silver Banshee, which includes prosthetic cheekbones, the wig, special contact lenses and a lot of white and black makeup. “The contacts are the least comfortable part of the process, but they are the coolest, so they’re worth it,” Ricci says.

Supergirl airs Mondays at 8 p.m. ET on CBS.