In the season 2, when Zoom captured Wally west and threatened to kill him if Flash doesn’t give up his speed force, he complied and then Zoom/Hunter Zolomon became the fastest man alive across the multi-verse. He tried to kill Barry but Caitlin intervened and he took her to Earth-2. Killer Frost (Caitlin Snow Doppel-ganger) is also locked in Zoom’s cage along with mysterious man in the iron mask, she cut a deal with Caitlin to help her break free from the cage in return for safe return to Earth-1. When she came out, she turned on Caitlin and tried to kill her only to be stabbed by Zoom.
The executive producer Andrew Kreisberg is excited at how things panned out and is hopeful of next season’s success, when he was asked about the possible character arc for Caitlin Snow, he hinted at the possibility of Caitlin’s mom and her doppel-ganger coming into the show, he said “We haven’t met Caitlin’s mother yet. We got a little talk between the two women, which will probably play out in Season 3.” She was once mentioned in the show when Caitlin Snow met her Earth-2 doppel-ganger Killer Frost, she said to her they both share estranged “Icy” mothers.
Kevin Smith, a popular director who directed an episode of the Flash, he is all set to begin shooting another episode for the upcoming season. He tweeted an image which revealed the title of the episode and it’s Killer Frost. This triggered a speculation that Earth-2 doppel-ganger of Caitlin Snow/Danielle Panabaker would return to the show. But how can she come back ever if she is dead? The fans speculated that she can return as a result of Flashpoint, maybe she is another Killer Frost in a multi-verse (maybe from Earth-3).
But now the truth is revealed and it’s truly amazing. The show-makers are indicating that Dr. Alchemy (one of the villains) will have the ability to activate the powers of dormant meta-humans. This is not a crazy idea at all, in fact, in first season Eobard Thawne killed Cisco that activated his meta-human powers (Vibe). This means that Caitlin Snow is a meta-human as she was also near particle accelerator explosion like Cisco, but her powers have remained deactivated till now.