Katherine "Kay" Rochefort is a detective and police officer in Lisvalletta's Special Crime Investigation Unit SEVEN-O. She works under the "Double Decker System," primarily partnered with Deana del Rio. Kay strictly adheres to protocols and regulations, embodying the By-the-Book Cop archetype. This approach often creates friction with her partner Deana, whose impulsive Cowboy Cop style contrasts sharply. Despite their differing methodologies, they form an effective Good Cop/Bad Cop team during investigations.

She displays notable enthusiasm for food, especially sweets, earning her the characterization as a "Big Eater." An unusual physiological trait makes her susceptible to intoxication from non-alcoholic beverages, a quirk that frequently generates situational humor. Within the eccentric SEVEN-O team, filled with individuals possessing pronounced quirks and unconventional backgrounds, Kay functions as "The Team Normal." Her relatively grounded demeanor provides a distinct contrast to the unit's overall eccentricity.

Professionalism and integrity are central to her actions. In one documented case, her participation in an investigation exposed Gary, a Dirty Cop within the narcotics division who attempted to steal and sell SEVEN-O's anti-Anthem serum. Kay's commitment to proper procedure proved instrumental in his apprehension, highlighting her role in upholding ethical standards within law enforcement.