Who is Mrs. Prior from The Eye in the Door and what is their importance?

Mrs. Prior's first name is not revealed in the narrative. Billy's parents have been married for twenty-eight years. Billy's mother is afraid of Harry Prior because he is abusive. No physical details are provided about Mrs. Prior. It is known that Mrs. Prior hates Hettie Roper because Hettie is a pacifist. It is clear that Mrs. Roper is willing to accept her husband's views of her own, since her conversation with Billy in Chapter 8 finds the character simply re-stating her husband's views. There is a passive quality about Mrs. Prior that Billy finds especially repugnant.