Nurse Catherine, a pink anthropomorphic lizard, dons a white nurse's uniform marked by red cross insignias on her hat and armband, accentuated with purple eyeshadow. She wields a large syringe as her signature instrument. Operating within Gregory House, she serves on the medical team alongside Dr. Fritz and later Cactus Girl. Her defining obsession is extracting blood from guests—especially humans—often to near-lethal extremes. This compulsion delivers her intense, fetishistic pleasure rooted in sexual thrill.

In "The Bloody Karte" narrative, Catherine displays professional negligence and malice: she mistreats Dr. Fritz, imprisons patients like Cactus Gunman to block their discharge, and heartlessly destroys a bloodless zombie corpse by exposing it to wind. Her romantic pursuits—fixating on Cactus Gunman, Judgment Boy Gold, and Hell's Chef—invariably end in catastrophe. She crushed Haniwa Salaryman during an embrace and attempted to woo Hell's Chef with homemade lunches, thwarted when Gregory stole them.

Within "Soul Collector," Catherine flees upon encountering the player while guarding a stolen soul. Retrieving it necessitates tripping her with a banana peel. Once soul-less, she aggressively hunts the player through the hotel. If captured, she unleashes a "Horror Show" syringe attack while declaring "Time for a blood test!"—draining the player's mental gauge. Her personality merges twisted medical zeal with violent outbursts when spurned or angered. Even amid romantic overtures, she physically assaults targets like Gregory and Hell's Chef after rejection, often citing medical jargon like "red blood cells" and "head artery."