Mirror of a Thousand Shadows

HPTMR, GWBL. AU. When the Dark Lady Firebrand tried to kill Harry Potter, she didn't manage it. Harry survives, goes to Hogwarts, and befriends Ron Weasley despite being Sorted into Slytherin. Ron's younger brother Tom starts at Hogwarts the next year, in possession of a mysterious diary from which a sixteen-year-old witch who calls herself Ginny speaks...