Prior to the events in the book and the movie, little is known of Jonathan other than having died under unknown circumstances, leaving his wife, Mrs. Brisby (never formally introduced with her proper name) a widow and their four children fatherless. After Mrs. Brisby is advised to seek out the rats of NIMH in order to move her critically sick son, Timothy, from the threat of farmer Fitzgibbon's plow, she is received warmly by the rats, especially after learning that she is Jonathan's widow.