If you have yet to see the brilliance that is "Fantastic Beasts and Where to Find Them" I suggest you click out of this article immediately because there will be spoilers. You have been warned.
After much anticipation, I finally saw "Fantastic Beasts" this past week, and let me tell you I was not disappointed. I'm still not happy with Johnny Depp as Grindelwald (#NotMyGrindelwald) but that is for another time. One singular question has been plaguing my mind ever since I stepped foot out of the theatre: was Ariana Dumbledore an obscurial?
An obscurial is a young witch or wizard who develops an obscurus. An obscurus is a parasitic force of dark magic. A child develops an obscurus when their magical abilities are repressed. This is the main antagonist of "Fantastic Beasts" when we learn that Creedence Barebone is a very powerful wizard, but his adoptive Second Salem mother beats him, and his repressed magical energy develops into an obscurus.
Obscurus are very dangerous. A child's obscurus appears as a dark cloud of dark magic, and they burst out of their host because the child usually cannot control it. They are highly unpredictable, and the only two known obscurials were killed by their obscurus. Creedence is the only obscurial we know who was able to mildly control his obscurus, but was still killed by it in the end.
Now how does this relate to Ariana Dumbledore? As you may not know, Ariana Dumbledore was the younger sister of Albus and Aberforth Dumbledore. She was kept hidden away from the world from a lot of her life, and she died at age fourteen. When Ariana was six, and her magic was just developing, she and her brother Aberforth were viciously attacked by some muggle (non-magical) boys. After this traumatic event, Ariana never used magic again, and her mother Kendra Dumbledore kept her inside at most all times.
"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." --Aberforth Dumbledore on his sister Ariana
The way Aberforth describes her, in addition to what we see in "Fantastic Beasts" leads me to believe that Ariana Dumbledore was in fact an obscurial. As I said before, an obsurus is created after the repression of magical abilities and after her attack, Ariana refused to do magic. But magic isn't like a rewards card, it doesn't expire if you don't use it. So instead it turned inward, and developed into this parasite of dark magic.
There are of course other factors that lead me to believe she is an obscurial, the biggest one being the way her mother died. After the attack on Ariana, Kendra Dumbledore moved her entire family from Mould-on-the-Wold, a small wizarding village, to Godric's Hollow. She also kept Ariana secluded from the outside world, in order to keep her safe.
When an obscurus takes over a host, it lashes out and attacks whenever the host is in great distress. As we saw in "Fantastic Beasts", the host can sometimes be talked down, and the obscurus controlled. Aberforth Dumbledore did this with Ariana.
"I could get her to eat when she wouldn't do it for my mother, I could calm her down, when she was in one of her rages, and when she was quiet, she used to help me feed the goats." --Aberforth on his sister
When Ariana was fourteen she had an episode where her emotions and magic spun out of control. Aberforth wasn't there to calm her down and she killed her mother Kendra. The way this is described in the book, it sounds exactly like an obscurus.
Again, this is only my theory. You can put as much stock into it as you want, you can add on to it, you can do whatever you like with it. But in my opinion, all of the evidence points to Ariana Dumbledore being an obscurial.
