This was a really great story -- I loved the insight you gave us into both Petunia and Vernon as young people, and that you managed to make Petunia sympathetic while not candy-coating who she was at all. I'd never thought of it before, but of course Petunia would feel unloved and shunted aside compared to her sister, and her bitterness and jealousy (which was not unfounded) would lead her to become the character we all know now.
The final paragraph was especially telling -- again, I'd never really thought about *why* Dudley was so spoiled, but it makes perfect sense. Great story, Mystery Author. :)