I was the only one who saw her for what she was -- a freak! But for my mother and father, oh no, it was Lily this and Lily that, they were proud of having a witch in the family!"
-- Petunia to Harry (PS4)
Aunt Petunia is Lily (Evans) Potter’s older sister, and the wife of Vernon Dursley. The Dursleys live at number four Privet Drive, Little Whinging, Surrey. She is a tall, very thin blond with a long neck and an angular face.
Estrangement and bitterness
Petunia and Lily grew up in the town of Cokeworth (Pm). When they were younger, Petunia and Lily were very close, so when Lily began to show signs that she was a witch, Petunia was frightened; when Lily got the invitation to Hogwarts, Petunia was so unhappy about being separated from her sister that she wrote a letter to Dumbledore and asked if she could attend (of course, she couldn’t). By the time Lily and James were killed, Petunia’s loneliness and disappointment had hardened into jealousy and an utter revulsion of magic. It didn’t help that both Lily and Petunia learned first about magic from an odd, intense neighborhood boy named Severus Snape; wizardry will always be “freakish” to Petunia (PS4, DH33). Any mention of her sister upset her.
Petunia left Cokeworth and took a job with the Grunnings company, which is where she met Vernon Dursley, a junior executive who would give her nice dull security in life. She and Lily tried to have a relationship as they grew older, but Vernon and James Potter just didn’t hit it off. Vernon wanted to talk about cars, while James teased him about his Quidditch broomstick. Petunia had told Vernon that James was unemployed and in Vernon’s mind “some kind of amateur magician,” but James bragged about his family vault at Gringotts which was full of gold. The two couples just could not find common ground, and while Lily wanted James to make things right with Vernon, it never happened. After both couples married they never saw each other again (Pm). However not all the family feeling was gone: Petunia sent Lily at least one Christmas present – a “horrible vase”which baby Harry broke as he flew around on his miniature broom that Sirius Black sent him for his first birthday (DH10).
Petunia and Dumbledore’s protection charm
As an adult, Petunia is a nosey gossip who dotes on her son Dudley, keeps an obsessively immaculate house, and defers to her smug, blustering husband. Uncharacteristically, she also agreed to Dumbledore’s written request to take Harry in when he was orphaned (PS1).
We don’t know exactly what Dumbledore wrote, but according to him, it informed Petunia that by taking Harry in she was providing him with powerful magical protection. Dumbledore told Harry: “You need return there only once a year, but as long as you can still call it home, whilst you are there he cannot hurt you. Your aunt knows this. I explained what I had done in the letter I left, with you, on her doorstep. She knows that allowing you houseroom may well have kept you alive for the past fifteen years.” (OP37).
But she didn’t promise to love him; from the beginning, Petunia’s treatment of Harry is cruel and reprehensible (allowing Harry’s older cousin to pinch and prod him). In stark contrast to her overindulgence of her own child, Harry is treated like an unwanted servant, forced to cook, clean and do all the work in the garden (CS2).
If Petunia’s feelings for Harry ever softened, she never showed it. When Harry reached his majority and they parted for (perhaps) the last time, Petunia said good-bye and could not bring herself to say more (DH3). However, she did burst into tears when Dudley said Harry wasn’t a “waste of space” after all.
Excellent at cooking, keeping a spotless kitchen, and spying on the neighbors.
A petunia is a kind of small ordinary flower related to tobacco, potatoes and deadly nightshade. The name is French, taken from a South American culture's "petun" = "tobacco."
J.K. Rowling said it was a name she and her sister used during play pretend games for "unpleasant female characters," and that she may have unconsciously picked it up from a character in an old public information film who waves at a man while he's drowning (Pm).
Petunia in the Movies
The role of Petunia Dursley is played by Fiona Shaw (IMDb).
From the Web
Ode to Petunia Evans by raisin_gal
Can You Forgive Petunia Dursley? from Harry Potter and the Sacred Text