Mr. Henry (full name Henry Washington) is not part of the MacTeer family, but simply boards in their house.  Mr. Henry spends much of the book endearing himself to both Claudia and Frieda.  One of his more ingenious methods is to refer to them with the names of famous mid-century film stars such as Ginger Rogers or Greta Garbo.  One day, Henry gives the girls money to buy ice cream and sends them on their way.  When Claudia and Frieda return, they find Mr. Henry with two women of questionable reputation (Maginot Line and China).  Even though the two women are widely known as prostitutes, Mr. Henry convinces Claudia and Frieda that they are part of a Bible Study group together.  Yet, he still reminds them not to tell their mother about this.  Hmmmm, that should have been an immediate red flag!  Of course, Mr. Henry is finally thrown out of the house for touching Frieda inappropriately.