Midnight twins trilogy

Identical twins Meredith and Mallory Brynn have always shared one another's thoughts, even as they dream, but their connection diminishes as they approach their thirteenth birthday, and one begins to see the future, the other the past, leading them to discover that a high school student they know is doing horrible things that place the twins, and others, in grave danger.

Psychic twins Mallory and Meredith try to figure out why their baby brother, who is being cared for by a number of babysitters while their mother attends medical school and works, keeps getting sick, while Meredith endures the pain and heartbreak of falling in love with a ghost who died in the Vietnam War.