In the novel "10 lb Penalty" by Dick Francis, the theme of betrayal is powerfully illustrated through the quote, "People always kill Caesar. Don't trust anyone." This reflects the idea that those in positions of power are often vulnerable to treachery, highlighting the prevalence of deceit in personal and professional relationships. The emphasis on mistrust suggests that even the closest alliances can be severed by self-interest and ambition.

This message resonates throughout the story, as characters navigate a world where loyalty is rare and ambition drives individuals to betrayal. The reference to Caesar symbolizes the downfall of leaders who, despite their strength, are susceptible to the designs of others. Francis weaves this cautionary perspective into the narrative, encouraging readers to consider the fragility of trust and the potential for betrayal in their own lives.