Remember in the first book at the end when Harry asked Dumbledore wanted to kill him in the first place? well if you will recall Dumbledore replied with "Alas, the first thing you ask, I cannot tell you. Not today. Not now. You will know one day... put it from your mind for now, Harry. When you are older...i know you hate to hear this...when you are ready you will know." so i think iits ab this