When the full cast for Fantastic Beasts: The Crimes of Grindelwald was revealed, it was nearly immediately theorised that Claudia Kim's character might be a very familiar face. If you're familiar with Harry Potter lore, you'll remember that Voldemort had a trusty serpent and Holocrux by the name of Nagini.
It's unclear exactly how Nagini factors into the overall Fantastic Beasts: The Crimes of Grindelwald narrative, but Kim did dish up a few pieces of information that offer more context. But in Fantastic Beasts: The Crimes of Grindelwald, Nagini isn't a snake through and through - she's a human who can shape-shift into the slithering reptile.
"It will be so interesting to see another side of Nagini", Kim added. It's unclear what Nagini's intentions are at this point in the timeline, but she can also be seen beside Credence in the big battle against Grindelwald in the trailer. In this, she's a wonderful and vulnerable woman who wants to live. In a scene taking place at the circus, we hear Credence say "Nagini", and then watch as Kim transforms into the snake. I can't confirm she has powers as other wizards have.
In addition to this, Claudia Kim has kept up with fan theories and speculation in regards to the new Fantastic Beasts film and her character, but she's not going to spoil anything for anybody.
Now, if you're asking yourself how a flesh-and-blood human being could also be a snake, "Harry Potter" fans have already done most of the heavy lifting. "Everyone is so good at analyzing every element there is".
This reveal seems very Anakin-built-C-3PO to me.
In an interview with Entertainment Weekly, Kim was finally unleashed from her vow of secrecy and spilled all the details about her role as Nagini.
In the trailer, Dumbledore glances into the magical artifact - which the future Hogwarts headmaster once described as showing "nothing more or less than the deepest, most desperate desire of our hearts" - and sees. his former friend and schoolboy crush, Grindelwald. J.K. Rowling revealed that Dumbledore was gay, and that he and Grindelwald had some type of complex love story, years ago.