Caitlin Snow

Caitlin Snow, aka Killer Frost is a DC Comics supervillain, most famously an archenemy of Firestorm who later reformed as a hero. She possesses cryokinetic abilities, allowing her to generate and manipulate ice and cold, often absorbing heat to fuel her powers, which makes her resistant to cold-based attacks. Caitlin Snow in The Flash evolves from a compassionate, science-driven doctor focused on helping people (Hippocratic Oath) to someone guarded by trauma, eventually embracing her heroic, empathetic core while battling her darker, ice-powered alter ego, Killer Frost, a manifestation of her repressed pain, fear, and anger. She's known for her warmth, intelligence, loyalty, but also for internal conflict, as her powers create a separate, colder personality that contrasts with her desire to save lives. Caitlin Snow and Barry Allen share a deep, sibling-like bond as best friends and core teammates at S.T.A.R. Labs, evolving from colleagues to confidantes who deeply understand each other's losses (Barry's mother, Caitlin's fiancé Ronnie). While some fans "shipped" them romantically (Snowbarry) due to their chemistry and supportive moments, particularly in early seasons with near-kisses and strong emotional reliance, their relationship remained primarily platonic and supportive, with Barry ultimately marrying Iris West.