Hello there!
This is a Harry Potter fanfic, written by Quinnera Elviana and Bryony Rose. It's written in alternating points of view, Arianna's and Gwen's. The way it works is that Quinn writes from Arianna's perspective and Bryony writes from Gwen's perspective. It's written during the fifth book, and Arianna and Gwen are both in Harry's year.
Enjoy!