There was this Harry Potter fanfic I read on Aldiko book reader. It was about Harry and Hermione dying and then going back in time to their first year selves. However Hermione doesn't remember right away! Harry ends up with the Dursley's. He goes to Hogwarts and is kind of a genius there because he already knows all the things that are being taught.
In 4th year Hermione and Harry get married. They got married really young but they've known each other since the past life. They also get to be professors at Hogwarts regardless of their age. Another thing in that story they befriend Draco instead of Ron because Ron and Ginny most likely betrayed them in their past life.