The story of ‘Fantastic Beasts: The Secrets of Dumbledore’ looks set to pay off a key and intriguing line from ‘Harry Potter’ and the ‘Deathly Hallows’. The backstory of Albus Dumbledore was partially covered in the ‘Harry Potter’ books and movies, which explained his past relationship with the dark wizard Gellert Grindelwald, and made mention of the tragic death of his sister, Ariana. In both cases, though, there's much more to be explored and other possible secrets as well.
That's something the ‘Fantastic Beasts’ franchise is now diving into, with ‘Fantastic Beasts 3’ titled ‘The Secrets of Dumbledore.’ This comes after the introduction of the younger version of the character, played by Jude Law, in ‘Fantastic Beasts: The Crimes of Grindelwald,’ and will presumably focus mostly on the biggest secret of them all, which was revealed at the end of that movie: Dumbledore's secret brother, Aurelius, previously known to viewers as Credence Barebone.
The plot twist, combined with the title of ‘Fantastic Beasts 3’, makes it clear that the history of Albus and indeed his entire family will be under much greater scrutiny in the upcoming Wizarding World movie. Exactly what will be revealed remains to be seen, but the fact that is so much secrecy surrounding his past life and so many shocking truths ready to come is something that was setup in ‘Harry Potter’ and the ‘Deathly Hallows’. There, Aberforth tells Harry and co: "I knew my brother, Potter. He learned secrecy at our mother's knee. ‘Secrets and lies’, that's how we grew up." In the ‘Deathly Hallows’ itself, that is largely taken as reference to the fate of Ariana, who was killed in a three-way fight between Albus, Aberforth, and Grindelwald, though the exact circumstances have not yet been uncovered, but ‘Fantastic Beasts: The Secrets of Dumbledore’ could add much greater meaning to it. —Collider