She's Made of Deadly Nightshade (M)

Hattie Potter was the famous girl-who-lived, and twin sister of Harry Potter. While Harry was made of all that was good, Hattie was made of all that was bad. Arriving at Hogwarts, Hattie would notice how the potion's professor, Snape, had a disturbing obsession on her. While Harry wanted to defeat Lord Voldemort, Hattie wanted to join Voldemort.