Mr. Johnson is a respectable, middle-aged man who is married to Alicia Johnson, the confidante of Lady Susan Vernon. Mrs. Johnson hides her activity from him as best she can, such as her visits to Lady Susan and her lover Mr. Mainwaring, while he uses the excuse of his gout to stop her from going to the Lakes with the Hamiltons or to keep her from seeing Lady Susan.
He has an unspecified number of aunts who live in Bath.
He was the guardian of Mrs. Mainwaring before her marriage, and while he disapproved of the match, she counts on him to interfere when her husband begins to court Lady Susan. It is on a visit to his house to discuss the problem that Mrs. Mainwaring meets Reginald De Courcy, there to call on Mrs. Johnson, that she tells him the truth about Lady Susan. Reginald later writes to tell Mr. Johnson that he has ended things with her, and the two become close.
Mr. Johnson tells Mrs. Johnson to end her friendship with Lady Susan, or he will settle them in the country for the rest of his life, which she cannot tolerate. Lady Susan hopes the next attack of gout will be fatal and they can resume their friendship.