Caitlin Snow (Earth-1: Pre-Crisis)

"Frost, you are my sister, I love you. And I cannot lose you."

- Caitlin to Frost

Dr. Caitlin "Cait" Snow is a biochemist at S.T.A.R. Labs and the former host of Frost.

Caitlin discovered her split personality, Killer Frost, following the Flashpoint. Killer Frost took control of her body for criminal activities before they made peace with each other. Caitlin soon returned to Team Flash and was eventually split from Frost after an injury caused by Eva McCulloch's Mirror Gauntlet.

S.T.A.R. Labs
Prior to 2013, Caitlin and "Harrison Wells" was experimenting on Grodd, a gorilla. She then grew fond of him and took care of him. Caitlin then became the only person Grodd trusts and was considered a good person by him.

Killer Frost
At some point prior to 2019, Caitlin's split personality was created by her father and became a villain known as Killer Frost. Later, she sought help from her mother and was unable to cure herself. However, as time passes, she realised that Killer Frost is not truly a villain and worked with her to reform and become a member of Team Flash.

Years later, Caitlin fought his father's split personality, Icicle.

Rebranding as Frost
In 2019, Caitlin rebranded Killer Frost as Frost and allowed her to take over her body in order to finally live a life. Additionally, as Frost has been in the "passenger seat" of Caitlin's mind for years, she retains Caitlin's knowledge on biology and chemistry.

Crisis on Infinite Earths
In January 2020, Nash Wells was found unconscious in his own worksite. He was then brought to S.T.A.R. Labs and was treated by Caitlin. She was then approached by J'onn J'onzz, who gave her the memories of her Pre-Crisis counterpart. She then realised the destruction of the Multiverse was Nash's fault.

After the battle, Caitlin takes over her body once more and attended the moment of silence with Barry.

When Nash's body was taken over by Eobard Thawne, Caitlin was able to determine that the mind of Nash was also tangled with his Pre-Crisis counterparts'.

Doctor's Orders
When Barry started losing his speed, Caitlin and Cisco was able to create a Speed Gauge for Barry to monitor his speed. Despite the device, Barry insisted on using his speed to fight crime instead of letting Frost be on the field. Caitlin then briefly transformed into Frost and ordered Barry to stay, who did not listen and made Caitlin injured during the fight.

Leave of Absence
"Maybe instead of focusing on what you've lost, you should try remembering what you'll never lose. The reason you've beat Zoom, Godspeed, Thawne? It's because speed isn't what drives you. It's love. That's your true force, and there is nothing artificial about that. So as long as you stay true to yourself, you will always find a way to beat the bad guys. And gals."

- Caitlin to Barry Allen

Due to Caitlin's injuries during the fight against Kimiyo Hoshi, Caitlin attempted to use "ice healing" to speed up the process. However, it backfired and caused her to fall into a coma, until her teammates visits her at her apartment. After Frost agrees to seek help from Caitlin's mother, she left to the Arctic for tests and recovering.

Return
Four weeks later, Caitlin and Frost arrives back in Central City, fully recovered and ready to return to the field.

After the Invasion of Central City, Caitlin bid farewell to Ralph Dibny, who suffered from injuries after being exposed to high temperature.

Split from Frost
A week after the Invasion, Caitlin and Frost suffered from headaches and went for a sleep, only to wake up in separate bodies. They then approached Cisco Ramon and surprised him with their sudden change. Cisco later brought them to the Cortex and surprised Barry and Iris.

They then went to the lounge and discussed the prior events to the split. Barry then sped off to fight Psych and later Frost assisted the treatment of his injury. Cisco then started fixing the Quantum Splicer for the merge and the device was damaged by Frost. Caitlin then confronted her and Frost told her that she do not want to merge as she could finally live her own life without being inside Caitlin's body.

Hours later, Caitlin diagnosed the trio with panic attacks after fighting Psych and placed in their greatest fears. Frost was alone in the Speed Lab until Caitlin looked for her. While Frost fixes the Quantum Splicer and tell her about her own fears, Caitlin offered Frost to sleep in an extra room in her apartment and considered her a sister.

Time Pocket
In her apartment, Caitlin started to realize that Frost is becoming a separate person and diverged from herself. Caitlin then returned to S.T.A.R. Labs and was affected by the Time Pocket created by Deon Owens, with her appearance becoming that of 1950s. Luckily, it was reversed when Cisco and Chester, both being in 1998, convinced Deon to stop his actions. Caitlin then once again attended a team meeting where Cisco names the Forces of Nature.

The People v. Killer Frost
When Kristen Kramer arrived in Central City in order to arrest Frost, the Meta Task Force arrested Caitlin under an anonymous tip of Frost's residence. Cecile served as Caitlin's attorney while Caitlin convinced Frost not to break her out of the precinct. The call then allowed Frost to understand who the imposter of her actions was.

Frost was then allowed to discuss her next move with Team Flash, with the team assisting her legal battle. Caitlin was then present at the trial, where she attempted to sabotage the Metahuman Cure in order to prevent Frost's power removal punishment. Caitlin, Cisco and Allegra then went to the precinct and created a distraction for Allegra to deploy the Inertial Oximeter. However, Allegra was discovered by Kramer and Caitlin took charge, sabotaging the cure by herself. Unfortunately, Kramer accused Frost of the sabotage and Caitlin defended her "sister", telling the court that she did it. Despite all the efforts to protect Frost, she insisted that she should be sent to prison for life with no possibility of parole. Caitlin then bid farewell to her sister as she gets taken to Iron Heights.

Days later, Caitlin monitored an unconscious Alexa Rivera, who she discovered that her powers briefly activated when there were tremors. Barry and Iris then resurrected her with a small fraction of Strength Force energy.

After the "Unforgiving Storm" between the Forces of Nature, Caitlin was greeted by Frost in her own apartment and found out that Frost was responsible for the arrest of countless escapees of Iron Heights.

Goodbye Cisco
One day morning, Caitlin, Barry and Iris were called to the lounge as Cisco and Kamilla told them about their leave from Central City. Despite her sadness over her best friend leaving, Caitlin did not show any sign of sadness and requested Cisco's security badge. Cisco was disappointed over the team ignoring his important decision and later saw Caitlin talking to Barry on the second Rainbow Raider. Cisco then proposed a final mission. Caitlin then monitored their first confrontation with Rainbow Raider, where Cisco was hypnotized. Cisco and Caitlin then guided Barry to Rainbow Raider's location. However, Cisco's extensive joy affected Barry's sight and Caitlin attempted to stop him. Unfortunately, it was too late and Barry was affected as well. Caitlin then saw the two being extensively joyful, with no means of fixing them until Chester arrived and neutralized the effects.

Caitlin and Barry then told Cisco that they acted courageous to prevent their last day from being pitiful. They then worked together to defeat Rainbow Raider, and later planned a surprise party. Cisco then gave Caitlin his shirt on his first day, that says "Keep Calm and Han Shot First". The original members of the team soon sang Poker Face, the alleged favourite song of Barry Allen as shown in his Facebook profile page.

Former Powers

 * Transformation: Caitlin is able to transform into Frost at will until their separation.
 * Cryogenic Physiology: Frost was created in an attempt on creating an ALS cure by her father.
 * Thermokinetic Cryokinesis: As Frost, by drawing heat, Frost is able to freeze objects.
 * Superhuman Durability: Despite being hit with a bullet, Frost only suffers from minor injuries.
 * Accelerated Healing: Also known as "ice healing", Frost uses her cryokinesis to speed up the healing process.
 * Ice Breath: Caitlin, as Frost, is able to breathe out cold air out of her mouth and freeze objects.
 * Mental Connection: As a host of Frost, the both are able to talk to each other mentally.

Abilities

 * Expert Biochemist: Caitlin attended medical school and has the rank of doctor.
 * Expert Medic: Caitlin has proven to be an expert on treating patients.

Former Equipment

 * Frost Suit: As Frost, Caitlin wears a navy leather suit with a snowflake emblem on the chest as well as a blue jacket. As they are no longer in the same body, Caitlin does not wear the suit anymore.