Sir Pentious is bombastic, flamboyant, short-tempered, temperamental and persistent, and his personality seems to take cues from the classic "mustache-twirling" stock villains. He takes tremendous pride in his grandiose ideas of how evil and cunning he is, and at one point even openly declares "I'm so evil!"

He uses his mechanical genius to build weapons, such as a cannon and his airship. However, he is more than capable of showing remorse and has a sense of honor. He demonstrates this when he accepts his defeat and "inevitable death" at the hands of the Hotel staff after being reprimanded by Vox for failing.

When Charlie forgives him, he is grateful and fully joins in his redemptive effort. Additionally, he is enthusiastic about Charlie and Vaggie's activities, more so than Angel Dust, even if it were an act.