|Han, a Gryffindor Marty Stu, and Greta, a Slytherin Mary Sue, are pretty much made for each other. Han is a technical genius, having figured out Magical Theory and solved the paradoxical problem between magic and technology. Greta is a non-conforming rebel, opting out of wearing the Hogwarts uniform (because you can TOTALLY do that in a private school in the UK) and is a genius in potions and dark magic. Oh, and he's a werewolf and she's a vampire, but that's not actually that important. They just think it makes them more interesting characters with sufficiently tragic backstories. Never mind that they'll never talk about it or actually complain about it until they need to prove that their lives are SO MUCH worst than anyone else's.