Dolores Umbridge is not the witch she claims to be.

Sure, she worked her way to high-level positions within the Ministry of Magic, even serving as Headmistress at Hogwarts School of Witchcraft and Wizardry for a year. But her accomplishments came under false pretenses, according to a new "Harry Potter" story written by J.K. Rowling.

Just in time for Halloween, Rowling's released a new Pottermore.com story (via Today.com) all about the secret life of Ms. Umbridge, and here's one of the bigger reveals: She's a half-blooded witch!

Born to wizard Orford Umbridge and muggle Ellen Cracknell, Dolores was one of two children. Her brother was a Squib, unable to perform magic. Both Orford and Dolores were so sickened by the magic-free members of their family that they went their separate ways, with Ellen and her son returning to the muggle world, never to be seen again. From that day forward, Dolores presented herself as a pure-blood witch — just one of her many, many lies.

Rowling's story charts Umbridge's rise at the Ministry of Magic, beginning with an internship in the Improper Use of Magic Office at the age of 17. By age 30, she was in charge of the office, due to the ruthless tactics she covertly employed beneath her sugar-sweet demeanor. She rose even higher and eventually pushed her unambitious father out of the Ministry, denying all connections to him whatsoever. Yet another lie.

In fact, one of few ways to see through Umbridge's false exterior is to give the woman a glass of sherry and watch as her true feelings about Muggles come spewing out of her mouth. Rowling notes that "even those who were anti-Muggle found themselves shocked by some of Dolores's suggestions, behind closed doors, of the treatment that the non-magical community deserved."

There's much more in the story, including how Umbridge was instrumental in turning public opinion against Albus Dumbledore during Harry's fifth year at Hogwarts, why she hates Hagrid and magical creatures so much, and her final fate following the events of "Deathly Hallows." In an afterword, Rowling reveals that Umbridge was inspired by a loathsome instructor from her past.

"I have noticed more than once in life that a taste for the ineffably twee can go hand-in-hand with a distinctly uncharitable outlook on the world," she writes. "I once shared an office with a woman who had covered the wall space behind her desk with pictures of fluffy kitties; she was the most bigoted, spiteful champion of the death penalty with whom it has ever been my misfortune to share a kettle. A love of all things saccharine often seems present where there is a lack of real warmth or charity."

Rowling goes on to describe Umbridge as "one of the characters for whom I feel purest dislike," saying her "desire to control, to punish and to inflict pain, all in the name of law and order, are, I think, every bit as reprehensible as Lord Voldemort's unvarnished espousal of evil."

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