The letter felt strangely personal like Hermione’s hands should not be the ones to open and read it. What was she expecting? Some horribly cold message about muggle-borns and filth of the earth beseeching the Malfoy Manor with her presence? At the very least she didn't expect Narcissa to feel so warm and accommodating. It did not mix well with the idea Hermione had of Draco’s parents all these years.