Sweet Whispers, Brother Rush

Why had he come to her, with his dark secrets from a long-ago past? What was the purpose of their strange, haunting journeys back into her own childhood? Was it to help Dab, her retarded older brother, wracked with mysterious pain who sometimes took more care and love than Tree had to give? Was it for her mother, Vy, who loved them the best she knew how, but wasn't home enough to ease the terrible longing?