Kate was born into a long line of Navy Servicemen; along with her mother, she moved around from base to base as her father was posted. Eventually she would join the navy and later become a CIA agent. She would go on to marry and divorce multiple times, as of 2006 one of her ex-husbands resided in Florida. (Ninety Miles Away) The other works for the state department.
In 1995 Harper was sent to Florida to observe talks about the removal of the American trade embargo on Cuba led by Leo McGarry. There she witnessed Leo's (who was then Secretary of Labor) alcoholism in full effect. She prevented him from getting in the driver's seat and decided to drive him to wherever he was going. (Ninety Miles Away)
She was present at the dedication of the Bartlet Library. President Bartlet comments that he 'read her book,' and complimented her prose. Given her area of expertise, it is likely the book was foreign policy commentary.
- Agent for the Central Intelligence Agency. Her record was apparently VERY classified, after C.J. Cregg requested her service file and found nearly 90% of it was blacked out (Ninety Miles Away).
- 2005-2007 : Deputy National Security Advisor
- Has been married and divorced twice.
- Had a relationship with fellow White House staffer Will Bailey during the final year of the Barlet administration.
- Met White House Chief of Staff Leo McGarry when he was Secretary of Labor during a previous administration while she was on an apparent undercover assignment in Florida. He was apparently too intoxicated to remember her clearly.