Caitlin Snow-Allen

## Affiliations

### Home

* Caitlin and Sam's Apartment, Central City, Earth-25, in the Multiversal, Universe (Currently)
* Caitlin's Apartment, Central City, Earth-25, in the Multiversal, Universe (Formerly)

### Husband/Wife and Kids

* Ronnie Raymond (ex-fiancé)
* Sam Allen/Danny West/Bart Thawne (husband)
* Unnamed Heart (boyfriend) (in old multiverse when Sam died)
* Olivia Winchester-Allen (step-daughter)
* Isabella Allen (step-daughter)
* Kallie Allen (daughter)
* August Heart (son) (in old multiverse)
* August Allen (son)
* Henry Allen II (future son)

### Relatives

* The Snow Family
	+ Thomas Snow (father; deceased)
	+ Carla Tannhauser (mother)
	+ Frost (sister figure)
* The Allen Family
	+ Henry Allen (legal father-in-law)
	+ Eobard Thawne (father-in-law; husband's biological father)
	+ Nora Allen (mother-in-law)
	+ Barry Morningstar (brother-in-law)
	+ Iris West-Morningstar (co-sister-in-law)
	+ Nora West-Morningstar (niece; by marriage)
	+ Bart West-Morningstar (nephew; by marriage)

### Occupation

* **Original multiverse**
	+ Bio-engineer at S.T.A.R. Labs
	+ Vigilante (in secret)
	+ Member of Team Flash (in secret)
	+ Scientist at Mercury Labs (formerly)
	+ Criminal (formerly; Sam Allen turned her around)
	+ Henchwoman of Amunet Black (as Frost; formerly)
	+ Bartender (formerly)
	+ Medical student (graduated)
	+ Pediatric ophthalmologist (Flashpoint timeline)
	+ Henchwoman of Superman (altered reality; formerly)
* **New multiverse**
	+ Bio-engineer at S.T.A.R. Labs
	+ Vigilante (in secret)
	+ Member of Team Flash (in secret)

### Other Affiliations

* **Original multiverse**
	+ Team Flash (in secret)
	+ S.T.A.R. Labs
	+ Amunet Black's criminal organization (formerly)
	+ Savitar (formerly)
	+ Mercury (formerly)
	+ Mercury Labs (formerly)
	+ Sam Deegan/Superman(altered reality; formerly)
* **New multiverse**
	+ S.T.A.R. Labs
	+ Team Flash

## Appearances

### First Appearance

The Flash Fanfiction Part 1; Chapter 1: The Scarlet and Sapphire Speedsters Are Born

Dr. **Caitlin "Cait" Snow-Allen,** M.D. (née **Snow**; born February 1989) is a bio-engineer at S.T.A.R. Labs and a former scientist at Mercury Labs. She was working during the particle accelerator disaster and tended to Barry, and Sam Allen during their coma with Cisco Ramon until he woke up. After he began his crusade as "The Flash, and The Bolt" Caitlin became a member of their team with Cisco and Dr. "Harrison Wells", before discovering the latter's true identity as Eobard Thawne, and provides medical support for the team. Caitlin is the daughter of the late Dr. Thomas Snow and Dr. Carla Tannhauser, Sister Figure of the late Frost, Sister-in-law of Barry Morningstar, Co-Sister-in-law with Iris West-Morningstar, the Ex-Fiancé of the late Ronnie Raymond, and the Wife of Sam Allen. Mother of Kallie Thawne, and August Heart in the old multiverse, August, and Henry Allen, Aunt by marriage of Nora, and Bart West-Morningstar.

In the Flashpoint timeline, Caitlin is not a scientist but a doctor who is unwillingly brought into Ramon Industries by Barry, and Sam to help him restore the timeline. Following Barry's attempt to restore the timeline, Caitlin is once again a scientist at S.T.A.R. Labs, but she is also a meta-human with abilities similar to her Earth-26 doppelgänger, who she is afraid of becoming like. However, it was later revealed that she was a dormant meta-human all along due to her father using an experimental ALS treatment on her, when she was 10. After being taken over by her rising anger while using her meta-human powers and losing control of her emotions, Caitlin briefly started going by her doppelgänger's name, **Killer Frost**.

After suffering a clinical death from a seizure and subsequently being revived by her regenerative powers, her biochemistry was altered, culminating in her becoming fully consumed by her anger as Killer Frost, later encountering and allying with Savitar after the proclaimed speedster god reveals his true identity as a future version of Barry Morningstar. Later, between Cisco giving Caitlin the choice to cure herself rather than force it on her and watching Savitar nearly kill him, Caitlin finally regained her true personality and control of her powers. Despite this, Caitlin decided not to take the cure. Feeling lost to her own identity, Caitlin left Team Flash on good terms to rediscover herself. Six months later, having seemingly come to terms with her mistakes as Killer Frost, Caitlin finally decided to re-join Team Flash, only to discover that her Killer Frost-side had returned.

Shortly after returning to Team Flash, Caitlin once again began to struggle with her Killer Frost side and eventually lost control. Iris convinced both Caitlin and Killer Frost that they could try to be the same person instead of choosing one life or the other. As such, when preparing to serve as back up to Barry along with Cisco, she stated "Snow and Frost standing by", emphasizing that both Caitlin and Killer Frost were prepared to work together to help. When Nazis from Earth-X tried to invade Earth-1, she aided her friends in the battle that followed, earning Mick Rory's affection. In a battle against Clifford DeVoe, she lost her Killer Frost side as a result of DeVoe using Dominic Lanse's powers to create a mental block. After defeating Siren-X from Earth-X, Caitlin discovers that Killer Frost is still inside her, without the presence of dark matter. She later learns, from a suppressed memory, that Killer Frost has been with her since childhood, before she was exposed to the dark matter released by the particle accelerator.

After defeating DeVoe and getting Ralph back, she discovered that her father's death certificate was a fake and that he was actually alive. Barry, Cisco and Caitlin eventually found him hiding out in an old warehouse. However, he later revealed himself to be Thomas' evil alternate personality and attempted to kill the team and take over Thomas' body completely. During the fight, Caitlin managed to break through the mental block that DeVoe had created and regain Killer Frost. By late 2019, she'd begun referring to her alternate persona simply as "**Frost**".

Eventually, Caitlin and Frost are affected by exposure to the Mirror Monarch's rays, causing Frost's cells to replicate enough to create a new body and also separating their telepathic connection.