In 2003 Bookreporter.com interviewed Thomas Perry. What he said then about his "predatory characters" certainly applies to the villains of his novels published since then:
BRC: You often shed the spotlight on the predatory characters like Roy Prescott of PURSUIT and the unforgettable Edgar-winning BUTCHER'S BOY. DEAD AIM has nearly a dozen such characters including Parish, the supporting staff of the Self-Defense School, and several unsavory students. What intrigues you most about those types of characters?Read the entire interview.
TP: The characters you refer to as predatory and unsavory are useful. They're the ones who make a novel into a thriller. They're active, and most of the common virtues, the signs of a good person, are not. Reading a novel in which all characters illustrate patience, hard work, chastity, and delayed gratification could be a pretty dull experience. What intrigues me most about these "bad" characters is that they're not like us. Their actions aren't restrained or modified by the possibility of guilt or remorse. They think only of expediency, and so their actions have a certain elegance and decisiveness. They're disruptive and scary, what nightmares are made of. But at the same time, the commonplace statement about them is true: every character is the hero of his own story. Each has a justification for his actions that is convincing to him. It's fun to give these people voices.
The Page 69 Test: Silence.
The Page 99 Test: Nightlife.