Harri, Rose and the Philosopher's Stone

Harriet and Rosalie never thought of themselves as special. That was until the letters arrived. Now they're going to Hogwarts School of Witchcraft and Wizardry. But what's all this about them being the "Boy who lived" and why does everyone think that they're one person, and a boy? And what secret is the Headmaster trying to hide? Twinfic with a difference. Girl!Harry.