Lady Black: The Mastermind

Ever since Lord Voldemort, the most powerful Dark Wizard since Salazar Slytherin, had met his downfall five years ago-- a five year old girl was determined to become the greatest and most feared sorceress of the century. She was trained in the Dark Arts by her godfather, Corban Yaxley, until it was time for her to attend Hogwarts. But her lack of a mentor did not stop Alexandrine Elissabeth Gaunt from continuing on her journey to become the most feared Dark Witch of all time. Her power continues to grow as she advances through her years at Hogwarts, confirming Albus Dumbledore's suspicions as she slowly morphs into his worst nightmare-- an almost exact copy of her distant cousin, Tom Riddle. But Alexandrine has bigger plans than just gathering followers during her time at school. She has bigger, darker, and more evil plans than that. Alexandrine Black is a force to be reckoned with, and Merlin help any poor soul who gets in her way.

Disclaimer:
Most of the characters and plot belong to JK Rowling
The prefect's speech is not mine, I got it from Pottermore
Alexandrine and Draco are not cousins, they are fourth cousins

I own the rights to:
Alexandrine Black
Cepheus Black
Elissabeth Gaunt
Elora Zabini
And the changes I made to the plot