Who is The Tiger's Wife from The Tiger's Wife: A Novel and what is their importance?

The tiger's wife, who remains unnamed, appears in the second of the book's three narrative lines, which is the story of Natalia's grandfather's childhood. She is the wife of Luka the Butcher, and she is described as a mysterious enigma, who is both deaf and mute. As a result, she is easily and frequently manipulated, hurt, gossiped about, and abused. The father of her baby is never identified, and her relationship with the tiger is never clearly explained. She seems, in many ways, to be a figure of local myth and/or legend, an idea rather than a living person - a character in a sort of strange fairy tale - at least, that's what she seems to be to the young grandfather and, eventually, to Natalia.