What relationship did Mary have with her grandmother when the pair was living together during Mary's childhood?

When Mary was a child, she was terrified of her grandmother and her clouded, cataract eyes. Mary's stomach would clench whenever her grandmother came into the room, particularly since Grandma Moore decided that daily beatings were the only way to rid Mary of her bad behaviors. Mary was the first to see her grandmother's dead body, crawling with fire ants, but chose not to tell anyone what she saw.