Katie is arrogant, selfish, and narcissistic. She openly derides Charlie's plan to rehabilitate Demons. She cares mostly about her own image, the hottest stories, and the latest gossip.

She doesn't seem to care about, or even acknowledge Charlie's royal position in Hell, and openly expressing contempt for her and her ventures. She has also been shown to be homophobic, refusing to even shake hands with Charlie, claiming she "does not touch the gays" due to her standards.

Katie is aggressive and seems to always be on edge. She deliberately spills hot coffee on Tom's crotch, while insulting and threatening Charlie. At the same time, Katie does not tolerate insults in her direction, and when Charlie snaps and calls her a bitch, Killjoy instantly falls into a rage and rushes at the princess with her fists.