Who is Hilde Grossman from Drowning Ruth and what is their importance?

Hilda Grossman is Carl Neumann's second cousin once removed on his father's side, Hilda comes from Tomahawk, WI, to help care for his three-year-old daughter Ruth after Ruth's aunt Amanda is institutionalized. Strict, serious, and humorless, Hilda and Ruth instantly dislike one another. Hilda sees Ruth as a problem child and appears to enjoy punishing her. Carl wants to get rid of her but needs help with the cantankerous child. Ruth for a while appears to grow closer to Hilda but only to set her up for a prank that makes her go away, claiming that Ruth is a devil child.