J.M. McNabb makes the case that one particular fan theory explains so much of the J.K. Rowling books:
It always seemed odd that Harry Potter’s aunt and uncle, the Dursleys, would be good enough to take him in and raise him, only to keep him locked in a cupboard under the stairs and generally treat him like a moldering hunk of Hitler’s shit. Why not just dump him in an orphanage if they were planning on treating him like an old boot for the entirety of his childhood? In a series full of magical beings, one of the most fantastic elements is that these completely normal people managed to be so terrible without the use of any spells
… or did they? A theory by Graphic Nerdity claims that the Dursleys were originally a normal, supportive couple, but continued exposure to Harry’s cursed ass turned them into resentful hate beasts.
Why It’s Not That Crazy:
Harry, as we eventually find out, is technically a horcrux. For those of you who aren’t fluent in nerd, horcruxes are cursed objects containing fragments of the evil Voldemort’s soul, and they’ve been known to turn people into assholes. In the second movie, Ginny Weasley is brainwashed by a book that doesn’t even have “Dianetics” in the title, because it’s a horcrux. It contains a piece of the venomous soul of the lord of hate magic and wizard murder. We also see Ron start acting like a total dick after putting on a locket that’s, you guessed it, also a horcrux.
Most importantly, we find out later in the series that Harry himself has a part of Voldemort’s soul trapped inside of him, like Dick Clark and Ryan Seacrest. So if Ron and Ginny turned evil after being exposed to a horcrux over a matter of weeks and months, just imagine how the Dursleys could be affected after living with one for 10 years. Harry Potter was a magical cancer gnawing hungrily away their souls.
This discovery makes the biggest douchebags of the Potter-verse not villains, but victims. Heroes, even. The fact that their adoption of a child who was also a cursed object merely resulted in them turning into emotionally abusive turds instead of a family of secret cannibals is cause for commendation.