So this is my new thought based on the whole Harry as Horcrux theory. We all assume that Harry would have to die to remove this part of Voldemort's soul, but what if the Weasley twins invented a spell that would allow Harry to live or allow Harry to defeat Vold... in a way that he would not expect nor know how to defend as it would be completely new?? I mean why else would they have figured so heavily in all of the books and been kept in the movies when they easily could have been edited out??