In Harry Potter and the Chamber of Secrets, Tom Riddle (a.k.a. Voledmort) gains power as Ginny Weasley continues to write in his diary. As Riddle explains this to Harry Potter, he says that he used the diary not only to drain Ginny but also to pour a little of his soul into her.
Could this mean that because of this, Ginny has become one of Voldemort's Horcruxes?
As the Dementors entered the Hogwart's Express in Harry Potter and the Prisoner of Azkaban, Harry was obviously affected the most by their presence. However, it was noted that while most people in the cabin felt strange because of the Dementors, Ginny Weasley was "shaking like mad" during this experience. This occurred after the whole situation with Tom Riddle and the diary.
It has been said that at least two of the main characters will die in the seventh book. Perhaps Harry figures out that Ginny has become one of Voldemort's Horcruxes - which means he will have to sacrifice her in order to save the rest of the world from Voldemort's wrath. Only time will tell...
