The Sixth Sense follows Cole, a boy who is able to see and talk to dead people; and Malcolm, a child psychologist who tries to help Cole, but in the end it’s Cole who helps Malcolm.

I read this as one book when I was twelve or so. It's about a couple who are destined to be together until a car accident kills one of them. Tristan comes back as Ivy’s guardian angel. He tries to save her from being murdered, but if he does save her, he will no longer be her guardian angel.