When Nora, Perry, and Julie are talking about what they would want to be when they grow up, if it weren't for the pesky zombie plague, Nora says she wants to be a nurse. That's right: in this undead version of Romeo and Juliet, Nora is Juliet's nurse.
The similarities pretty much end there. Nora and Julie are the same age, for one, and unlike Juliet's nurse, Nora doesn't betray Julie. She remains loyal to the very end of the book, even to the point of pulling a gun on Julie's dad. (He deserves it. Trust us.)
Nora pretty much exists to give Julie a sassy best friend. Everyone needs one of those, especially when the danger of zombies lurk at every turn. Nora's also our token minority character in a world that's very white and gray. Julie remarks that Nora's dad was Ethiopian. Of course, nothing says "rich Ethiopian heritage" like the last name "Greene." What, does this stadium have its own little Ellis Island to change the name of all the immigrants?