Love

Love was an emotion which K9 Mark 2 struggled to understand, receiving no clear answer when asking his human company. (TV: Aeolian) Peri Brown defined it to Yrcanos, the man who would become her husband, (TV: The Ultimate Foe) as "when you care for someone or something more than yourself", "sometimes more than life." (TV: Mindwarp)

The First Doctor noted love as an example of emotions to the Cyberman leader Krail, questioning "Have you no emotions, sir?" (TV: The Tenth Planet, Twice Upon a Time)