No matter which way you slice it ("it" being the crooked birthday cake, of course), the Dursleys were mean. Like, in a cruel words-off between them and the Bellatrix-Draco-Voldemort trifecta of terror, we'd have to bet on Dudley and his horrible parents FTW - easy money.

But even after seven "Harry Potter" books and eight movies, we were still so left confused about the source of the Dursley trio's constant contempt for their poor orphaned little nephew and his tragedy-stricken folks. Because yeah, Petunia was always jealous of Lily for being the center of attention and having all the special skillz, but that alone didn't justify locking the poor lad in a below-the-stairs broom closet, did it? No. NO.

Alas, J.K. Rowling has finally put an end to the mystery of why the Dursleys were so damn mad at the Potters, and even though we now know a little bit more of their irrational rationale, we ... still don't like them.

In a new set of "Deathly Hallows"-related writings for Pottermore, Rowling revealed that the Dursley-Potter family feud began way back when Lily was in her last year at Hogwarts, and she went home to introduce her beau James to Petunia and her fiance Vernon. And the boys butted heads instantly.

"James was amused by Vernon, and made the mistake of showing it. Vernon tried to patronise James, asking what car he drove [so] James described his racing broom."

That's when things got sticky and political. Def not polite dinner table conversation material -- but Vernon did start it.

"Vernon supposed out loud that wizards had to live on unemployment benefit. James explained about Gringotts, and the fortune his parents had saved there, in solid gold," Rowling wrote for the site. After that it was all downhill between the four, and before their untimely deaths, the last communication the Potters had with Vernon and Petunia was the announcement of Harry's birth.

Rowling added that the reason Vernon held Harry is such low esteem all his life was something he shared in common with Professor Snape. Uncle Vernon's vitriol, she wrote, "stems in part, like Severus Snape’s, from Harry’s close resemblance to the father they both so disliked."

Petunia, on the other hand, was meant to show some hesitation from her hatred -- but not much.

"I wanted to suggest, in the final book, that something decent (a long-forgotten but dimly burning love of her sister; the realisation that she might never see Lily’s eyes again) almost struggled out of Aunt Petunia when she said goodbye to Harry for the last time, but that she is not able to admit to it, or show those long-buried feelings," Rowling explained in the post. "Although some readers wanted more from Aunt Petunia during this farewell, I still think that I have her behave in a way that is most consistent with her thoughts and feelings throughout the previous seven books."

Mission accomplished.