As I watched Fantastic Beasts and the Obscurial information began to appear in reference to Credence, I remembered this quote in reference to Ariana Dumbledore: “It destroyed her, what they did: She was never right again. She wouldn't use magic, but she couldn't get rid of it; it turned inward and drove her mad, it exploded out of her when she couldn't control it, and at times she was strange and dangerous. But mostly she was sweet and scared and harmless." Ariana was assaulted by Muggles and was from then on unable to control her magic. Since Ariana was unable to control her magic, she had outbursts and at the age of 14 and killed her mother.
Ariana died when Aberforth and Albus Dumbledore were dueling Gellert Grindelwald and she attempted to intervene when she was around 14 years old. Ariana suffered from outbursts of uncontrollable magic, which is a trait of an Obscurial. Ariana comes from an extraordinary powerful magical family and while Newt stated that no Obscurial has lived past the age of 10 – Ariana, like Credence, may have been able to. Newt also said, “Before wizards went underground, when we were still being hunted by Muggles, young wizards and witches sometimes tried to suppress their magic to avoid persecution. So instead of learning to harness or to control their powers, they developed what was called an Obscurus.” Since Ariana was assaulted by the Muggle boys, her magic became uncontrollable – a trait of an Obscurial. And Ariana’s mother, Kendra, was killed by Ariana’s magic – something only an Obscurial would be able to do, just like Credence did in Fantastic Beasts. However, it brings up the question as to why Kendra was killed since the Obscurial seems to have control over whom they kill as evidenced by Credence. I wonder if Kendra was possibly abusive to Ariana? Or why didn’t Ariana go to Hogwarts to learn how to control her magic because she was over 11? Maybe Ariana was mad at her mother for not allowing her to go to Hogwarts like her brothers did?
But, I hope that more is revealed in the upcoming Fantastic Beasts installments. And I hope I’m right about Ariana being an Obscurial because it would be such an amazing plot twist that was hinted at over 10 years ago. Rowling is brilliant and I’m sure she’ll provide an explanation eventually.