The Slytherin Queen

Only a few knew about the girl who lived in the attic, and the Dursleys planned on keeping it that way. They were scared of her and her freakish ways. They thought they could beat it out of her to make her submit. And that's precisely what the old fool planned. He didn't know that she wasn't a naive little girl who would roll over for him. Ophelia Potter had a plan to tear the Wizarding World down brick by brick for trying to break her. She didn't care who got in her way in the process, but they would pay every last one. After all, Slytherins don't lose. They rule.

A few OCs
The storyline doesn't completely follow the plot