Many Missed a Detail That Changes Everything in 'Harry Potter': Harry's Aunt Knew Snape Personally

One seemingly random line from Aunt Petunia in Harry Potter and the Order of the Phoenix always felt a bit odd. But now it’s clear: it wasn’t just a slip-up. It was a glimpse of the past — one that Harry never uncovered. Harry’s aunt spent her whole life pretending to despise magic. But one comment gave her away: she knew much more than she let on — and not just second-hand.

In Order of the Phoenix, Petunia Knows About Dementors

When dementors attack Dudley, Petunia blurts out, "They guard the wizard prison, Azkaban." Then she falls silent. Harry is stunned. She quickly tries to cover it up: "I heard it from that awful boy, talking to Lily."

Harry assumes she’s talking about his father, but attentive readers will realise she meant someone else entirely.

In Deathly Hallows, Petunia Overhears Snape

In the seventh book, Harry Potter and the Deathly Hallows, Harry sees Snape’s childhood memories. In one scene, a young Severus tells Lily Evans — before she ever sets foot in Hogwarts — about dementors and Azkaban. They're sitting by a lake, discussing the magical world, and Snape is clearly trying to impress her.

Unbeknownst to them, Petunia is hiding behind a tree, eavesdropping with fascination and envy. The young wizards spot her, and Snape reacts coldly, chasing her off.

Why This Changes Everything

This detail shatters the image of Petunia as someone completely removed from the magical world. She didn’t just overhear something in passing—she witnessed magic up close. She knew Snape’s name. She heard him talk about dementors. And, most likely, she longed to be in her sister’s place.

That dream was crushed the day her Hogwarts letter never came. Her bitterness toward Harry isn’t just petty resentment—it’s the pain of someone rejected from a world she yearned to be part of.

Rowling planted this clue back in Order of the Phoenix—but only revealed its full meaning in the final book.