I truly believe Draco and Luna are cousins. Luna’s mother has to be Lucius’ sister, in my eyes. Hagrid said all Purebloods are related one way or another, and I think he’s right. Movie Draco and Luna look so much alike, they just have to be family. I simply think Lucius is ashamed of the fact that Luna is family of him, and forbid Draco to speak of it, but that Luna and Draco actually meet up and talk like real cousins would. I believe they are cousins, and secretly friends.