Of all the colorful characters in the CW's popular Arrowverse television series The Flash, one of the most fascinating is S.T.A.R. Labs scientist Caitlin Snow. As one of the most brilliant minds in Central City, Caitlin straddles the line between hero and villain more than any other character in the Arrowverse as a crucial member of Team Flash while suppressing her villainous alternate persona Killer Frost.

Possessing powerful cryokinetic abilities, Caitlin's demeanor completely changes whenever she transforms into the icy figure, and she bcomes considerably more antagonistic to her friends and family. With the threat of Killer Frost permanently taking over the good-hearted Caitlin Snow has been a consistent struggle for the character throughout the series, CBR is taking a deep dive into the character's comic book history and her possible future in the Arrowverse.

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KILLER FROST IN THE COMIC BOOK DC UNIVERSE

First created in 1978's Firestorm #3 by Gerry Conway and Al Milgrom as Crystal Frost, the original Killer Frost fell in love with her professor Martin Stein shortly before she transformed and gained deadly cyrokinesis powers. She also gained the ability to drain the life-force of those around her, after trapping herself in a thermafrost chamber when he spurned her advances. Now calling herself Killer Frost, the villain battled Stein and Ronnie Raymond in their fused form of Firestorm, only to die after absorbing too much energy from the superhero.

While a second Killer Frost arose in Louise Lincoln, an entirely new version of the character named Caitlin Snow debuted during DC Comics' New 52 era. Created by Dan Jurgens in 2013's Fury of Firestorm: The Nuclear Man #19, Caitlin was a S.T.A.R. Labs scientist assigned to a remote arctic outpost. When the installation was attacked by the terrorist organization H.I.V.E., Caitlin was doused in an experimental coolant that caused her transformation. Since then, the new Killer Frost bounced between siding with heroes and villains, first as a Firestorm antagonist and then as a member of the Suicide Squad and, later, an incarnation of the Justice League formed by Batman during the DC Rebirth era.

HOW CAITLIN BECOMES KILLER FROST ON THE FLASH

Arrowverse-Killer-Frost

The Arrowverse incarnation of Caitlin Snow, portrayed by Danielle Panabaker, is a scientist working at S.T.A.R. Labs in Central City with her fiancé Ronnie Raymond. After Eobard Thawne, disguised as Caitlin's boss Harrison Wells, causes the particle accelerator explosion that gives Barry Allen and dozens of other meta-humans powers, Ronnie disappears and is presumed dead. He eventually resurfaces, merged with Martin Stein as Firestorm. However, he dies for good while closing a singularity that threatens the planet, leaving Caitlin to mourn his death while serving as a key member of Team Flash putting her scientific knowledge to use.

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After the Flash creates subtle variations to the timeline after creating the Flashpoint alternate timeline, the adjusted timeline saw Caitlin receive cyrokinesis abilities, which she keeps a secret from the rest of the team. As the cryokinesis grows more uncontrollable, she develops an increasingly malevolent personality and begins referring to herself as Killer Frost. Warned by her scientist mother, Doctor Carla Tannhauser, that she continues to tap into her new abilities the change may be permanent, with Caitlin wearing a power-suppressing necklace to keep Killer Frost in check.

Gravely wounded, Caitlin's colleague and love interest Julian Albert removes the necklace so Killer Frost's healing abilities can save her life, leading the revived Caitlin to fully transform. Months later, Caitlin and Killer Frost reach a sort of compromise and begin regularly changing between the two personas, as Killer Frost gradually begins showing more heroic tendencies. In Season 5, Caitlin not only discovers that she exhibited signs of cryokinetic abilities as a child but inherited them from her father, the supervillain Icicle, instead of from the particle accelerator as previously thought.

KILLER FROST'S POSSIBLE FUTURE

Killer Frost in The Flash

Throughout The Flash Season 5, Caitlin's Killer Frost persona has returned sporadically, most notably when Caitlin was confronted by her villainous father. The revelation that Caitlin's powers don't come from dark matter unleashed by the particle accelerator effectively makes her immune to Cicada's power-suppressing technology, which will make her invaluable in the final fight against the Season 5 antagonist and hints at Killer Frost's likley return.

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With the realization that Caitlin has lived with the Killer Frost persona within her all life, it suggests that Caitlin Snow will never be free of her violent alter ego. However, she also might never be completely consumed by it, and the two sides of Caitlin Snow may be able to co-exist in an ongoing compromise.

Airing Tuesdays at 8 p.m. ET/PT on The CW, The Flash stars Grant Gustin, Candice Patton, Carlos Valdes, Danielle Panabaker, Tom Cavanaugh, Jesse L. Martin, Danielle Nicolet, Hartley Sawyer and Jessica Parker Kennedy.