The "romance" of the era is often seen in the camaraderie between the Doctor , Jo , Brigadier Lethbridge-Stewart , and Sergeant Benton —a chosen family working in harmony.
The Doctor initially dismisses Jo due to her perceived lack of scientific background, but her bravery in facing the Autons and the Master quickly earns his respect.
The Master also makes his first appearance in this specific file/episode. Their relationship is the series' most complex "romantic" parallel:
The Master functions as the Doctor’s dark reflection, creating a storyline of obsession that persists for decades. Subplots and Romantic Tensions