Sophie's BFF makes a brief cameo in the very beginning of Chapter One, but drops out of the action for the rest of the book. She's got a crush on Sophie's brother, Josh, which makes Sophie a little bit uncomfortable. We never get to meet Elle in person, but we learn from her phone conversation with Sophie that she lives on the East Coast, that she's fashion-conscious, and that she never got out of her Goth phase (Lacrimosa is blasting in the background).
Sophie and Josh have come to rely on each other so much that they don't have too much need for friends, so it is interesting that the book opens with Sophie talking to Elle. Perhaps she will play a bigger part in future sequels?