[SPOILER] Fantastic Beasts: Is Ariana An Obscurus?

Ariana Dumbledore, an Obscurus? Now, let's talk about that big new theory. 

Like many fans, I shared that belief at first. Not anymore. Because there is always a flaw in the plans we make after starting a new J.K.R. story, and today, I am not so sure anymore this one works.

Obscurials usually don't live after 10 and Ariana died at 14. Not a problem: we who watched the Adventures of Newt Scamander, we know that some of them can. It's very rare, but it happens.

So far, nothing wrong with the "Ariana-is-an-Obscurus" story.

Now let's come to the reason of my doubt: Grindelwald was so sure the Obscurial was under 10, and so obviously surprised when he realised it was Credence. Obviously, he never imagined a child could survive that long... He met Ariana. He's clever. He knew the Obscurus he was tracking in New-York was very powerful, therefore, probably, a bit special. If really Ariana was an Obscurial, he would have considered the possibility, wouldn't he?  And yet, it seems he didn't!

Ariana might have been an Obscurial for what we know... Or not. But if she really was, and if indeed Grindelwald knew, then it highlights a little lack of self-consistency.

Since when are J.K.' stories not consistent? And even more, since when is J.K. unveiling her big plans on the very first chapter of a saga? Let's trust her to clear up everything in the end... I bet it won't be that simple nerds!