Growing up in the Death Eaters" shadows, it was impossible not to soak in all of their hidden knowledge, a knowledge that would give her away as an impostor the moment she spoke to any other wizard. The Hallows, for instance. No matter how much she protested that Ron and Harry focus on finding Voldemort and set aside all thoughts of the Hallows, she had no doubts that the Hallows existed. And that Voldemort would stop at nothing to find them.