Without reviewing my tapes, two scenes stand out in my memory.
When Jason first arrives at Collinwood, there's no sign yet of his intentions. Introducing himself as an old family friend, he and Carolyn go to the drawing room where he cheerfully regales her with tales of his travels and his memories of a Collinsport from 18 years before. Throughout the scene, Dennis Patrick plays Maguire as a charming, witty, entirely pleasant and likeable soul. However, later in the storyline after he has begun to blackmail Liz and reveal his darker nature, Jason catches Carolyn rifling through his possessions. No longer concerned with impressing her, he grabs her roughly and threatens her (I think it's at this point when he tells her she'll need a new place to live after the wedding.) In this performance, Patrick plays Jason with barely contained violence and ruthlessness, and it's quite a reversal form the Jason we first met.
The first scene demonstrated Jason's affability while the second showed his cruelty. That Patrick exhibited each opposing trait so convincingly testifies to his skill with the role.
ProfStokes