They are established as former friends with a deep, shared history on Gallifrey. Their interactions are often described by fans as a "cosmic dance," filled with mutual admiration and intellectual flirting despite their lethal goals.

While not a traditional romance, their bond is often viewed as one of the most emotionally intimate in the classic series, built on loyalty and "rescuer" dynamics. The Antagonistic "Bond": The Doctor and The Master

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.

This episode marks the debut of as the Third Doctor's new assistant. Unlike her predecessor Liz Shaw, Jo’s relationship with the Doctor begins with protective skepticism but quickly grows into deep mutual affection.