We still have another year before the second movie in the Fantastic Beasts and Where to Find Them series releases its second movie. For the fans, that means a year of fan theories about the next movie and the series as a whole. It has been released that the last movie will take place in 1945 which is the year of Dumbledore and Grindelwald's duel. But how will the five movies connect Newt Scamander and his crew with the famous Dumbledore and Grindelwald duo?
1. Dumbledore and Newt's Secret Mission
One common theory that most fans seem to accept as canon even though it has yet to be confirmed is the idea that Ariana Dumbledore is an Obscurus. All signs point to the validity of this theory. However, according to ScreenCrush and their interview with Jackson Bird, there is already more evidence linking Dumbledore and Newt. In the first Fantastic Beasts movie, Grindelwald makes a comment about Dumbledore's fondness of Newt. This suggests that they already have a relationship. The theory takes this a step further by claiming that Dumbledore sent Newt on this mission to America to find Grindelwald.
http://screencrush.com/fantastic-beasts-harry-potter-connection-theory-video/
An article on CinemaBlend, however, disagrees with this theory and has a strong case as to why.
2. Voldemort's Origin Story
Coincidentally, 1945 is the same year that Tom Riddle graduated Hogwarts. Will the Fantastic Beasts movies then connect to Voldemort's story as well? According to Melissa Anelli on The Leaky Cauldron, it seems likely that Credence (who is almost universally believed to be alive) could end up in the same orphanage as Riddle, and that Grindelwald could go there and indirectly influence Tom. Though Riddle may not be the focus of Fantastic Beasts the way he was in Harry Potter, it is probable that he will make an appearance in the Fantastic Beast movies in some way.
http://www.the-leaky-cauldron.org/2016/11/18/fan-tastic-theories-and-where-to-find-them/
3. Newt gave Aragog to Hagrid
We obviously know that Newt loves beasts and has a tendency to find them harmless even when they can cause serious damage. He also has some sort of relationship and connection to Dumbledore. So, it makes sense that Newt could've come to Hogwarts and inspired Hagrid. This also would tie back to Tom Riddle who linked the Basilisk murders to Aragog and Hagrid.
https://moviepilot.com/p/fantastic-beasts-theory-did-newt-scamander-give-hagrid-aragog/4145336
4. Dementors come from Obscuri
This does not directly relate to the Newt and Dumbledore/Grindelwald connect, but it's still an interesting theory.
http://nerdist.com/our-possibly-wild-theory-about-...
Though we can theorize, we will have to wait another year before we can get any closer to finding out the truth.
