The haunting of Sierra is a book by Thefantasticmissfox.
It's the story of a family that had just moved from the big South African city of Johannesburg to the smaller Sierra, a few miles from there. The protagonists are two twelve-year-old twin sisters, Melissa and Alissa, who are also the narrators (each chapter is narrated by one of the two teenagers).
If in the beginning the girls are best friends, everything changes after they moved in their new house and visited the prohibited room, in which they saw portraits of a girl killed in multiple ways. Since then Alissa becomes strange, evil and behaves badly, sometimes causing damage to Melissa, who has discovered from a local boy that Sierra is a haunted city. In fact, thirty, years before their arrival, a girl had disappeared (later she was tortured and murdered) and no once could tell where her corpse is.
It is said that the portraits of her murder appeared in some houses and they reappeared if anyone tried to move them out, then those who touched them would be possessed by its spirit.
The third chapter is narrated from Alissa's point of view and tells her visions and the actions that she carries out, always with the purpose of hurting Melissa.
Quite creepy, I must say. If you're 12, don't read it at night if you've just moved in to a new house lol.