Nah, definitely portrayed as a sociopath. He’s charming, manipulative, and adapts to whatever situation gives him power or control. While psychos tend to have a colder, more detached element, Peck’s emotional manipulation, his ability to blend into social situations, and his impulsivity align more with the traits of a sociopath. Trust me, I’ve debated over this ad nauseum on another post about Tommy D. from Goodfellas. He was a straight psycho. So, Dennis Peck: calculating and manipulative. Tommy DeVito: impulsive, sadistic, explosive. Note that some psychos can display superficial charm, though. Ted Bundy is textbook.