The mind is not a book, to be opened at will and examined at leisure.

Yes, that's the first thing you heared from him and that phrase has stayed stuck in your mind through the years. He was your potions teacher and he taught her occlumency.

You looked at him with admiration, as a figure of respect and experience, a mentor, a friend.

You've heard those words many times, but now is when they make sense.

With the start of the war, you have decided to join the Order of the Phoenix. Dumbledore put You two to work together, he will be your guide now, your mentor, again, teaching you the art of being a spy.