Eric Foreman’s nickname for Remy Hadley in House M.D. is “Thirteen.”
Remy Hadley is a physician who joins House’s diagnostic department during the fourth-season hiring competition. The nickname comes from the number she wore during that selection process: she was identified as candidate number thirteen. The name remains attached to her even after she becomes a regular member of the team.
Olivia Wilde played Hadley, who is usually called Thirteen by House and her colleagues. The character is an internist with a particular interest in diagnostic medicine. Her storylines include Huntington’s disease, relationships, bisexuality, and difficult decisions involving patient autonomy.
The character’s surname is Hadley, and “Remy” is her given name, so “Thirteen” is not a medical title or a codename. The numeral is also not a reference to the number of diagnoses she makes. It is a nickname created by the show’s team-selection plot.