Fredericka is the secretary of Jonathan Stonagal during the formative years of Nicolae Carpathia as narrated in the prequel trilogy. It is not known whether she was Raptured.
Personality
In addition to being Stonagal's secretary, she is adapt at using the primitive telecommunication and email facilities available decades before the Rapture. She is extremely efficient, being able to book a flight or track down a person's phone number before online resources were available, and calls Stonagal "Mr. S" even in person.