Disclaimer: I do not own Harry Potter, it all belongs to JK Rowling and I am not making any profit off this.

A/U Rewrite: Dudley has a little sister two years younger than him. A magical little sister.

Short chapter, because it is prologue-y. Enjoy!

On June seventh, in AD 1980, Dudley Dursley was born. A little bit later, on July thirty-first, in AD 1980, Harry Potter was born.

Two approximately 1 year 5 month old boys watched a thin woman and her fat husband talk.

"Vernon, Vernon!" the thin woman screeched. "Can you believe this!? We are actually going to have a little girl!" Vernon looked up from his coffee at his wife, who was pacing and wringing her hands.

"Calm down, Petunia. I was happy when Dudley's birth was announced, but now I have a son to carry on the Dursley name but a girl? No big deal. And I am not even going to mention... him."

"I suppose you are right, Vernon. I just cannot dress Dudley-kins in sweet, little dresses and do his hair up in itty-bitty pigtails!" Vernon buried his face in his coffee mug to keep from laughing.

Seven months later, on August thirteenth AD 1982, Arabella Marjorie Dursley was born. She had blonde hair like her brother and Slytherin green eyes. Unknown to her or her parents, a man in a dark brown cloak watched with satisfaction as her mother carried her out of the hospital and into the car.

As a child, Arabella was a very inquisitive young girl who would try anything just to try it. Her brother avoided her for the shame of being seen with his "dumb, baby sister" and her father pretty much ignored her. She herself learned to avoid her mother for fear of being dressed up in "sweet, little dresses and itty-bitty pigtails!" As a result she turned to the only member of the family she could, her cousin, Harry Potter.

One of Arabella's earliest memories was from when she was two. It was the day Dudley and Harry first went to preschool.

"Mummy, Mummy, I want to go too!" Arabella cried from her car seat between Harry and Dudley in the back.

"When you are older Bella, you can go to school too," her mother said, focused more on the road than her daughter.

"I want to go now! Dudley always gets what he wants, even if it is the middle of the night! Daddy loves Dudley more than me, doesn't he?" Arabella pouted. Petunia did not even bother to turn around this time.

"Don't worry, Ara," Harry whispered, using his special name for her. Everyone else called her Arabella or Bella, but Harry always called her Ara. "I will tell you everything so you do not even have to go. It will be like you really were there."

"It's gonna be boring!" Dudley pouted. Both Dursley children were very good at pouting.

"That's what you think," Arabella sulked. That afternoon, Harry indeed told her all about it. He let her watching him do his homework.

By the time she was three, she was learning as much as any kindergartener simply by reading Harry's and Dudley's schoolbooks. She was a very bright girl. She started first grade at the age of five. Her goal was to catch up with Harry and Dudley, who both, at age seven, were in second grade. She never got to achieve that though.