Hart was a former partner of Jack Harkness during their time in the Time Agency, both professionally, and sexually. During their time in the Agency, Hart was trapped in a two-week time loop with Jack for a period of five years. While briefly arguing over who the "wife" was in the relationship, Hart agreed that he had been "a good wife, too". He had been in rehab for drink, drugs, sex and even murder. By the time that Hart reunited with Jack, the Agency had closed. (TV: Kiss Kiss, Bang Bang)