Ariana Dumbledore

Ariana Dumbledore is the younger sister of Albus Dumbledore, noted Headmaster of Hogwarts and mastermind behind the downfall of Lord Voldemort. Rumored by many to be a squib, Ariana was hidden away by her mother Kendra and father Percival after being emotionally scarred by a group of muggle boys at age 7. As a result of this incident, Ariana refused to do any magic, allowing her magical power to well up inside of her, periodically releasing in uncontrolled explosions.

Due to the timing of Ariana being hidden away, those in the outside world who knew of her existence believed her to be a squib, an idea that was popularized by Rita Skeeter in her scathing biography of Albus Dumbledore.

Ariana was killed accidentally during a three-way duel between her brothers Albus and Aberforth and Gellert Grindelwald. It is unclear which of the three caused her death, although Aberforth blamed Albus for it and never forgave him.

A portrait of Ariana hangs in the Hog's Head Inn in Hogsmeade, concealing a secret passage to the Room of Requirement in Hogwarts Castle. This passage appeared only after the students had begun using the Room of Requirement in their efforts to fight the Hogwarts administration under Headmaster Severus Snape.