**SPOILER WARNING: There are key plot points below on Fantastic Beasts: The Crimes of Grindelwald. Stop reading now if you haven't seen the movie.**
There's a lot going on in the Fantastic Beasts sequel. The film covers Grindelwald's (Johnny Depp) rise to power in Europe after escaping American captivity, delves into Newt's (Eddie Redmayne) relationship with Leta Lestrange (Zoe Kravitz), and even introduces us to a younger Dumbledore (Jude Law) and reveals his early machinations in what seems to be a looming wizarding war. The biggest reveal in the film, though, concerns the character of Credence Barebone (Ezra Miller), the Obscurial from the first film, thought dead by Newt but revealed to be alive and in Paris very early on.
Credence's true identity is important to many people because of an ancient prophecy, and while some believe him to be Leta's long lost brother Corvus, Grindelwald reveals to him in the film's final scene that he is actually Aurelius Dumbledore, secret younger brother to Albus and, Grindelwald theorizes, the "only entity" capable of killing Dumbledore.
In a new interview with IGN, Miller explained how he came to know his character's true identity, and if you think the events of the film are convoluted, wait until you hear this. Miller was first told about the twist by producer David Heyman while the cast was still promoting Fantastic Beasts and Where to Find Them, but Miller is a major Harry Potter fan, and Heyman didn't have all the details. This created... confusion.
"I'm like, 'Wait a second, David, how do I get an English accent? How do my eyes turn blue? This doesn't make any sense.' And he's like, 'That's all I know, that's all I can tell you for now,'" Miller said. "Essentially, I thought I was Aberforth Dumbledore, the known brother of Dumbledore, and David — we were on the loud bus. It was a miscommunication."
Aberforth Dumbledore is, of course, well known to Potter fans for his role in the latter books in the series. A member of the Order of the Phoenix, he had a strained relationship with his brother Albus, and was the owner of the Hog's Head Inn in the village of Hogsmeade. Little is known about Aurelius, but he is of course a different matter altogether. Miller had no way of knowing that, though, until he expressed his bafflement to writer J.K. Rowling later.
"I see Jo, and I'm like, 'Jo, Jo, Jo. How do I acquire the English accent? How does it make any sense? We know where Aberforth was from the time that he was born.' And Jo said, 'Did David Heyman tell you this?' And I was like, 'Yeah,' " Miller said. "She was like, 'Oh, no. You're not Aberforth; you're Aurelius.' And I was like, 'Who's that?' And she's like, 'Nobody knows about him but me, darling, and you now.'"
The face Miller makes in the above video, when he recalls learning a Wizard World secret directly from the source, is all of us at the end of The Crimes of Grindelwald.