Maladicta, one of the soldiers in Monstrous Regiment. A female vampire pretending to be male, who gave up blood to coffee and cigarettes. A very clever and cunning character.
After being deprived of coffee for a few days, she begins to experience extreme hallucinations and paranoia - she is convinced that they are being followed by 'Charlie' (although it later turns out that they were being followed by Sargent Angua of the Anhk-Morpork city watch). Her hallucinations are described as 'contagious', with other characters also experiencing hallucinations when near her.