Severus: Do not stand in the way of the Dark Lord, Minerva.
Minerva: Wait, Harry. I'll handle Professor Snape. You are a coward Severus, you always were. Stupify. I won't stand for this.
Severus: You cannot win. It's not too late for you, Minerva, just give me the boy.
Minerva: Harry Potter is under my protection.
Severus: The Dark Lord wants him. I suggest you hand over the boy.
Minerva: You will never take Harry Potter from this school.
Severus: Oh, very good. It's easy to see where the boy learned his lack of discipline.
Minerva: Me, I care to educate, not dominate. A difference you seem unable to appreciate, Severus.
Severus: Potter always was trouble.
Minerva: Coward! Coward! It appears your headmaster has done a bunk.
Voldemort: I wish you no harm. Give me Harry Potter and I, Voldemort, shall leave Hogwarts untouched. Give me Harry Potter and you will be rewarded.
Minerva: Shhh! I presume you have a reason for returning Mr. Potter. What is it you need?
Harry: Time. Time to find the Diadem of Ravenclaw.
Minerva: Do what you have to do. We'll secure the castle. Longbottom, Miss Weasley, Finnigan, I have a job for you.
Flitwick: You realize, of course, that nothing we do will be able to keep out "you know who" indefinitely.
Minerva: That doesn't mean we can't hold him up. Piertotum Locomotor! Hogwarts is threatened. Man the boundaries and protect us.
Flitwick: Protego Maxima!