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 6, who attacked her when she couldn't show them magic she had used earlier (at age 6 magic starts to appear but is uncontrollable, only occurring occasionally). 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. Her father, horrified by what had become of his daughter, attacked the children that caused it. He was sentenced to Azkaban, however, he never said why he attacked them as otherwise Ariana would be taken away to St. Mungo's.

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.

She began a close friendship with her brother Aberforth, her their brother Albus, she did not like as he stayed in his room and never came to see her. Aberforth had a special bond with her that allowed them to work together, such as if she would not eat food her mother offered her, her brother could give her the food and she'd eat it.

On day she had yet another uncontrollable explosion, accidentally killing her mother. Aberforth found it hard to look after her and continue with his education.

Ariana was eventually 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. However Aberforth did say she couldn't control her magic during the fight so it is possible that Ariana accidentally killed herself.

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.