Sweet Whispers, Brother Rush — Virginia Hamilton

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?

Whatever secrets his whispered message held, Tree knew she must follow. She must follow Brother Rush through the magic mirror, and find out the truth. About all of them.