UNIT’s steadfast leader and descendant of Kate Lethbridge-Stuart. Practical, loyal, and deeply committed to Earth’s safety, Sam has inherited both the responsibility and the stubborn courage of his family line. Though often bewildered by the Doctor’s rambling explanations, he proves himself brave and resourceful in crises. His dynamic with the Doctor is one of cautious trust—he follows, questions, and occasionally grounds the Doctor when his plans grow reckless.