Despite the Harry Potter movies being satisfactory, there are details that distort some characters. It is the case of Petunia Dursley, the Muggle aunt that raised The Boy Who Lived.
Due to the lack of complexity that she was treated in the movies, Petunia became just a villain, while in the books she is more than that. To understand what led her to mistreat Harry, we must go back to the past.
The sisters Petunia and Lily were close. They used to play together and even got along well, except for rare discussions and divergences of opinion, given that Lily had more of an open mind to what was different. However, when Severus Snape came into Lily’s life, a lot changed.
The two quickly became friends. They spend a lot of time together and share one rare aspect in common: the magic. As Petunia was a Muggle, Severus associated his friend’s sister to his dad, who was also a Muggle and treated his mother, who was a Wizard, abusively. Snape, therefore, never missed a chance to offend or hurt Petunia’s pride, who, conservative and with the instinct of protection of her older sister, also couldn’t see something positive in him. To her, Severus was a weird boy who competed with her for her sister’s attention, dragging her to things that, in her vision, were malicious.
“-That’s where you’re going’, said Petunia with relish. – A special school for freaks. You and that Snape boy … weirdos, that’s what you two are. It’s good you’re being separated from normal people. It’s for our safety. […]
-You didn’t think it was such a freak’s school when you wrote to the Headmaster and begged him to take you.
Petunia turned scarlet.
-Beg? I didn’t beg!
-I saw his reply. It was very kind.”
– Harry Potter and the Deathly Hallows
Lily had abilities that Petunia would never have. Therefore, it is comprehensible that the young Petunia felt jealous of their relationship and envied her sister’s condition. After all, Lily was not just a sweet and intelligent girl, but she had become literally a magical person, what charmed their parents even more.
It’s not surprising that Petunia had sent a letter to Dumbledore negotiating her acceptance at Hogwarts. Like any child, she also wanted to have magical powers. Everyone wants to be special in some way, and the anguish of not feeling like that becomes worse when there are comparisons.
“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 Dursley in Harry Potter and the Philosopher’s Stone
From Petunia’s point of view, the magic was what separated her from her sister. Her defense mechanism was to hold on with pride to an identity entirely conservative to suffocate the frustration that she would never live the magic, starting to see anything unusual as an aberration. By joining someone who shared the same thought, that got worse. Vernon encouraged the worse in her personality, which intensified the bitterness she felt. So Petunia took more and more distance from everything involving Witchcraft and, consequently, her sister.
Years later, there was another reason to abhor the magic: she was responsible for her sister’s death. Dumbledore, who once rejected her, sent a letter that shook all her plans to have a “normal” life, informing that Harry would only be safe in a home directly connected to his mother.
In welcoming the baby Harry, Petunia found herself before her childhood. Just like she and Lily, Harry and Dudley were kids at the same age, but one of them had a gift the other would never have. Not wanting Dudley to feel the same, Petunia channel her pain into the overly spoiled treatment she gave her son to make him feel as special as Harry.
Her decision of raising the nephew resulted in a series of events that aggravated her fear of the Wizard community, such as having the house invaded by letters, the sister-in-law inflated as ballon and the living room destroyed after a visit from the Weasleys, that ended with Dudley’s tongue growing nonstop. Not to mention the pig’s tail, which despite causing a lot of laughter, it was unpleasant to the mother’s eye.
Later on, even after experienced the real dangers of the Wizarding World, with a Dementor attacking her son, and finally having to move for safety reasons, Petunia kept the promise of keeping Harry under her roof and opposed when Vernon wanted to kick him out.
Petunia has her share of guilt for being complicit in the treatment given to Harry, who was unjustly punished for everything that happened in the house, locked away many times in his room, without making any noise, pretending that he didn’t exist. However, paraphrasing Sirius Black, the world is not divided into good and bad people. We all have light and darkness within us. What defines us is the side with which we choose to act, and Petunia Dursley acted in the right side of the fight of a world she was could not even be part of, even though it has made her relive her worst traumas.