Elizabeth "Liz" Weatherby was a friend of Harriet Tachyon. She was a retired librarian who knew Harriet for some time.
Informed Flaw Elizabeth insists that she isn't a very adventorous person, in contrast to Harriet. Mostly because of how she has lived her life - without adventures. It worked well for her for decades, so it's a bit distressing for her to accept that maybe she had an adventurous side after all.