Who is Elizabeth Osbourne from The Mark of the Assassin: A Novel and what is their importance?

Elizabeth Osbourne is daughter of a liberal U.S. Senator and prominent Washington D.C. attorney, Elizabeth is married to Michael Osbourne. She is not thrilled with his occupation but tolerates it because he is, at least, assigned to a desk job at CIA headquarters. More than anything, Elizabeth wishes to begin a family and is undergoing in vitro fertilization toward that end.