Yesterday was Harry Potter's unpleasant cousin Dudley Dursley's birthday. In honor of the day, J.K. Rowling updated her Pottermore fan site with an extensive background story that revealed new information about Dudley, and Harry's Aunt and Uncle, Petunia and Vernon.
The new Pottermore post disclosed how Vernon and Petunia met, as well as the first time they were introduced to the magical Potter family. Rowling explained how she picked the name for Harry's Aunt and Uncle. "Vernon is simply a name I never much cared for," she wrote. "'Petunia is the name that I always gave unpleasant female characters in games of make believe I played with my sister Di."
According to Rowling, Vernon and Petunia met at an average office job where Petunia quickly fell in love after Vernon accepted the fact that her sister Lily (Harry's mom) was a witch. The passage read, "He told Petunia solemnly that he would never hold it against her that she had a freak for a sister, and Petunia threw herself upon him in such violent gratitude that he dropped his battered sausage."
After the two muggles (non-wizards) were engaged they went on a double date to meet Lily and her new boyfriend James Potter. The night went horribly after Vernon implied that wizards have no money and James bragged that, in fact, he's filthy rich. Vernon stormed out of the restaurant when James attempted to explain the wizarding bank, Gringotts.
The two sisters, Lily and Petunia never see each other again. Petunia does not invite Lily to be a bridesmaid at her wedding fearing she would be overshadowed by the witch. The last contact the two had had was Harry's birth announcement. Lily was killed by dark wizard Voldermort shortly after, which left Harry orphaned.
For more backstory on the world of Harry Potter, head over to Pottermore.com.