From the very beginning, J.K. Rowling had most of her Harry Potter series planned out. The acclaimed author was (and still is) meticulous about the details surrounding her Wizarding World, including bits of canon that never even made their way into the books. But there's one questions she always feared she might be asked: What is Dumbledore's wand made out of?
While it might seem reasonable for her to worry about being grilled over why she had killed off certain characters, for example, the topic of Dumbledore's wand was a dangerous one for the author. Why? Simply because she had already figured out that Dumbledore had the Elder Wand, a detail she wouldn't reveal until Deathly Hallows. If she had said that Dumbledore's wand was made of elder wood before telling the tale of the Peverell brothers in the seventh book, fans would've quickly connected the dots as soon as Harry, Ron, and Hermoine learned about the Deathly Hallows.
"That would have been quite a telling question," Rowling told TIME about Dumbledore's wand. "Because I had this elder thing in my mind, cause elder has this association in folklore, it's the death tree. I thought 'What am I going to say?'"
The question would have given away a crucial spoiler, but Rowling's fears were all in vain as no one ever ended up asking her about it.
All that worrying on Rowling's part was thankfully for nothing. But years later, her admission just proves she really did have everything planned from an early stage.