Cathleen McGinley: Take a Stand (Book 1)

A Squib who should have died doesn't, and nothing will ever be the same. Muggle-born Cathie has been bullied her whole life. Now she must find her worth at Hogwarts while fighting off trolls, bullies, and of course her twin brother Cadence. Another OC-in-the-Golden-Trio's-year type of story, although a bit out of the ordinary (I hope). Rated T to be safe. Minor cursing.