Who is Grandma Bradshaw from Jacob Have I Loved and what is their importance?

Grandma Bradshaw, who lives with her son Trutt, is described as a wicked, vicious old woman who is obsessed with the Bible. Unfortunately, she doesn't practice its teaching, but rather uses it as a basis to judge the others living on the island. Grandma, like LOuise, was in love with the Captain when she was a child.