Danielle Panabaker as Killer Frost
“The Flash” executive producer Andrew Kreisberg said that Caitlin’s (Danielle Panabaker) brain chemistry has been severely altered, and that’s why her metahuman powers make her alter ego, Killer Frost, evil. The CW

“The Flash” executive producer Andrew Kreisberg explained why Caitlin’s (Danielle Panabaker) metahuman powers, when unrepressed, turn her into villainous Killer Frost.

In a recent interview with Entertainment Weekly, Kreisberg revealed that Caitlin’s powers have affected her brain, and that’s why her alter ego is evil, which is not the case with most of her fellow metahumans at S.T.A.R. Labs.

“Obviously her meta powers have severely messed with her mind, so it’s not like Barry Allen (Grant Gustin), who is still Barry Allen even though he got super speed,” Kreisberg explained. “Her brain chemistry has been severely altered.”

READ: Jesse L. Martin teases Joe-Cecile drama in Season 3, episode 20 of “The Flash”

Panabaker also offered an explanation about Caitlin and Killer Frost’s relationship during her recent chat with TVLine. “I had a lot of conversations with the writers, particularly around episode 7 [‘Killer Frost’], which was Kevin Smith’s episode,” the actress shared, “and the way that this has been explained to me is that it’s almost like there’s this dark person inside of her who’s itching to get let out.”

“It’s like an addict, almost, this person who craves the malice and the harm that she can do to people,” Panabaker added of Killer Frost. “Caitlin, with the help of the necklace and the cuffs, was able to keep that in check, but now the Killer Frost inside her has become a too strong and too powerful. … It’s going to be a much more difficult battle this time to see if good can triumph over evil.”

At the end of last week’s episode, Killer Frost came face-to-face with Savitar. During their meeting in the woods, Savitar told her that he has been waiting for her to offer her salvation.

“You want to cure me? Turn me back into Caitlin Snow? Killer Frost asked the God of Speed.

“No, I want to make sure Caitlin never returns,” replies the hulking speedster.

When Killer Frost asked why she should trust him, Savitar, without hesitation, revealed his true identity to her. And that ultimately convinced Killer Frost to align herself with the big bad. “There’s a relationship that exists there that prompts Killer Frost to turn her loyalty to Savitar very quickly,” Panabaker teased to Entertainment Weekly. “Once it becomes clear who Savitar is, you start to understand why Killer Frost aligned with him so quickly. Killer Frost’s quick alignment with Savitar informs a lot of the decisions that she makes.”

Kreisberg, however, noted that Killer Frost isn’t simply an ally for Savitar. “She plays a unique part [in Savitar’s endgame],” the exec producer revealed. “He’s not just looking for an evil cohort; she’s actually necessary for him to pull off his plans.”

In an interview with TVLine, Gustin revealed Barry’s reaction when he finds out that Killer Frost is now taking orders from Savitar. “Barry is devastated to find out that Killer Frost helped Savitar,” Gustin said of the unforeseen alliance. “It looks like she’s helping Savitar, so this is another step in the future actually coming true.”

So in tomorrow’s Season 3, episode 20, Gustin said that Team Flash is “making sure [that] there’s no team-up [between Killer Frost and Savitar] and they get their friend back.”

“The Flash” Season 3, episode 20, titled “I Know Who You Are,” airs on Tuesday, May 2 at 8 p.m. EDT on The CW.