Stockholm syndrome

, according to Peri, was a psychological condition characterised by "the kidnapped becoming close to the kidnapper". She suspected that Erimem's sudden decision to marry Dracula was an indication that she was perhaps suffering from the syndrome. (AUDIO: Son of the Dragon)

suggested that Ian Chesterton and Barbara Wright suffered from Stockholm syndrome as they bonded with the First Doctor and Susan Foreman. He realised that Ian, as a native of 1963, would be unaware of the term. (AUDIO: The Destination Wars)

Behind the scenes
In the real world, the term "Stockholm syndrome" was coined in 1973.