Originally the familiar of Serena Fredrick (Lonnie Partridge), Kit gets fed by her mistress for the last time before a homicidal warlock shows up and changes everything.
With the Triquetra symbol displayed as a medal on her collar, Kit watches from under a car as Phoebe (Alyssa Milano) has her first premonition and diverts an accident.
After following Prue (Shannen Doherty) and Phoebe home, the cat gets into the house through an open window. Prue jokes that Piper (Holly Marie Combs) isn't home unless she's turned into a cat, but that's clearly not the case as the third sister turns up a few seconds later.
Although no reason is given for why the Halliwell sisters accept the cat into their household without question, it's a minor quibble given the fast pace of the first episode. All witches need a familiar, and Kit remains with the girls throughout the series.