The Flash's Danielle Panabaker on Caitlin's Killer Frost duality

WARNING: This story contains major spoilers from the season 4 premiere of The Flash. Read at your own risk!

Caitlin Snow returned to the team during Tuesday’s season premiere of The Flash — but so did Killer Frost.

As viewers saw in the May finale, Caitlin (Danielle Panabaker) was somewhat able to get her villainous alter ego under control, explaining to Barry (Grant Gustin) and Cisco (Carlos Valdes) that she’s not quite Caitlin anymore, nor is she Killer Frost. That’s because, as viewers then discovered in Tuesday’s premiere, she’s actually both. While Caitlin appears to be back to normal, she’s torn between the two in a split personality-like way. Particularly when threatened, Killer Frost rears her white locks and makes her presence known, with Caitlin only able to take back control once the threat diminishes.

“She’s still struggling with her identity and this duality of her life right now,” Panabaker tells EW, teasing that Killer Frost could come out at any moment. “This year is a little bit different because now some time has passed. I feel like during season 3, they were dealing with the shock of this other person living inside of Caitlin, and now it’s been a little bit of time, there’s less surprise about it, and I think Caitlin is trying to understand it a little bit better, and she’s also trying to stay in control a little bit more. Is she successful at that? Not necessarily.”

For now, Caitlin is hiding her struggles from the team, desperate to keep her icy half under control. “She’s trying to deal with things herself,” Panabaker says. “As a doctor, I think it appeals to her to try to understand and try to get a handle on what’s going on, and she is not as quick to reach out to members of Team Flash for support as she has been with different things in the past.”

That will prove difficult as Caitlin’s past catches up with her. As teased in the premiere, Caitlin is trying to quit working for Amunet — that’s Amunet Black (Katee Sackhoff), a.k.a DC Comics villain Blacksmith, the badass boss of an underground black market for supervillains. “Caitlin is struggling and attempting to separate herself from Amunet,” Panabaker says. “Obviously Killer Frost is an incredible tool and an incredible ally to have. She’s very powerful, so I don’t think Amunet wants to let her go.”

“The six months between the end of season 3 and the beginning of season 4, for Caitlin, are not completely addressed from the beginning,” Panabaker adds. “We’re going to start [to see that]. It’s going to be hopefully a slow burn as we start to see a little bit more about what Caitlin was up to and her struggle over those last six months, and then unfortunately, as tends to happen, things that we try to keep secret find a way of bubbling to the surface, and sometimes in inopportune moments.”

Even though Caitlin seems to be under control, some fans may question why Team Flash is quick to welcome Caitlin back into the fold after she aligned with Savitar to kill Iris (Candice Patton) last season. “I think that as Caitlin and as Team Flash come to understand a little more about Killer Frost and Caitlin — and that while they may inhabit the same body, they are not the same person, and they certainly have very different intentions — I think my hope is that Team Flash, and Iris in particular, can forgive Caitlin and that they don’t necessarily hold Caitlin accountable for Killer Frost’s actions,” Panabaker says. “They are two different people, even though they look the same, and I hope that Team Flash, and Iris in particular, can forgive Killer Frost ultimately as well.”

The Flash airs Tuesdays at 8 p.m. ET on The CW.