J.K. Rowling is the queen of dropping new factoids about the characters in the Harry Potter universe while she's talking to her fans. In various Twitter threads and interviews, Rowling has revealed a variety of facts about everything from characters' future children to the religion of Hogwarts students to characters' sexualities. Recently, she revealed some new info about why Grindelwald sought Credence in Fantastic Beasts: The Crimes of Grindelwald, and it all has to do with Grindelwald being a seer. But, what is a seer? It turns out that the powerful type of wizard that plays a big role in Fantastic Beasts.
In a deleted scene on the Blu-Ray of Fantastic Beasts: The Crimes of Grindelwald, Dumbledore reveals to Newt that he knew Grindelwald would be in New York looking for Credence because he is an obscurial. Dumbledore says that years ago Grindelwald had a vision telling him that an obscurial would help him defeat his enemy. But how did Grindelwald have that vision? It's because he is a seer.
Seers are especially gifted wizards who are able to see the future using their Inner Eye. True seers are supposedly very rare, but when they exist, they can predict prophecies that are recorded in the Hall of Prophecy in the Ministry of Magic. A wizard must have great skill in order to be a seer, as is the case with Grindelwald. In the Harry Potter series, the only exposure to seers fans got was through the occasional-seer Sybill Trelawney. But, her skills only showed up sporadically, unlike Grindelwald who has much more control over his prowess as a seer.
The fact that Grindelwald can see into the future gives him a great deal of power over other wizards because he constantly has information that others don't have. Grindelwald knew to look for Credence because of his abilities as a seer. He also alludes to his visions during a conversation with Credence in Fantastic Beasts and Where to Find Them. Towards the end of the movie, Grindelwald (disguised as Graves) tells Credence that he had seen hints about the obscurus in New York. Though it isn't completely clear in the movie, he's revealing that he saw vision because he is a seer.
Rowling gave fans some info about Grindelwald and his ability to see shortly after Fantastic Beasts was released in 2016. She tweeted:
With that tweet, Rowling complicated things even further. Not only is Grindelwald a seer, but he's also a character with less-than-virtuous motives. While he can see the future, other characters and the audience can't always trust what he says at face value. One fan pointed out that Grindelwald may have seen "the child's immense power," but he doesn't give Credence all the details about it because he doesn't want to reveal all that he knows about him and his obscurus.
If the fact that Grindelwald is really powerful thanks to his abilities as both a seer and a liar isn't enough, Rowling has also revealed that Grindelwald is an occulmens. That means that Grindelwald is able to protect his mind from people who might try to read it. Because of that, it's difficult to ever get one step ahead of Grindelwald, let alone fully know what he's up to at any given moment. The only way fans will really be able to figure out what's going on with him is when the next installment of Fantastic Beasts comes out, or when Rowling tweets another fact.