Some Family History
Harry Potter was five the first time he realised his Aunt's visitors might not be as 'normal' as she thought. He wouldn't have had any idea, if George, who was smaller than he was, hadn't successfully knocked Vernon out when he tried to attack Harry. George had simply held both her hands out, and suddenly there was an invisible barrier between Harry and Vernon. Vernon belted his head on it when he tried to break through.
Harry was horrified. George, on the other hand, was confused. "Mum? Aunt Petunia? What happened to Uncle Vernon?" Petunia just stared at her for several seconds, before finally speaking. "Well, Cissy, it looks like the family tradition is being continued," she said, softly. "I'm George, this is Frances, why'd you call one of us Cissy?" George queried, confused.
Petunia smiled, sadly. "George, your mum, Harry's mum and I were triplets. We were born to parents who didn't have our family's special talents, although all the rest of our family does. Lily and Frances have the talent, I don't. We were all adopted out, because our parents had been disowned by our mother's father, and there was only so much our father's parents, and Mum's mother, could do for us. Lily and I were adopted by the same couple. Frances was adopted by your grandparents, George." Having explained how the triplets were divided, Petunia pushed forward, giving as much information as she could without attracting Dumbledore's attention.
I call your mum 'Cissy' because she was born Narcissa Meredith McGonagall-Evans. Your grandparents, to protect her from our mother's father, changed her name. They christened her Frances Narcissa Meredith Kirrin. I was born Petunia Elizabeth McGonagall-Evans. Harry, your mum was born Lily Minerva Judith McGonagall-Evans. Our parents, Jack and Jenny, dropped the McGonagall to protect us from our grandfather."
She smiled then. "Harry, this revelation is going to have a major impact on your life. I can't do very much to protect you from Vernon, it's all I can do to keep him from attacking Dudley some days, particularly if something strange happens and you're not around to blame. But I promise you I will do my best to treat you the way I should have treated you for the past four years. I have gone along blindly with Vernon's treatment of you, and I am deeply ashamed of myself for that. I should have attempted to protect you from Vernon, and I failed you. Hiding behind the excuse of being afraid of Vernon is pathetic, since I'm so many years older than you, and I should be able to face my fears."
Petunia was almost crying. "I was stupidly jealous of Lily. Everything seemed so effortless, so easy for her. She had everyone's approval, and our parents adored her because of her talent, which I lacked. It was only years later that I would learn of our family's history. One day, Lily brought home a tabby cat with odd markings around its eyes. My life hasn't been the same since. I was desperately jealous of Lily because of the world she was disappearing into each year. I found it impossible to believe, at first, that I had a place in that world, or that I would be welcomed there. I was shocked when I first met our parents. David and Meredith Evans are wonderful people. I wish you could meet them. But it isn't widely known that I am related to them, so you can't. Not yet. You won't even meet Tabby until you get your acceptance letter, unless some coincidence occurs."
Harry was staring at her in shock. Petunia had never opened up this much to him. Hell, she'd never even spoken more than "Good Morning" in a friendly way before, and yet here she was giving him his family history, and all because of cousin George.