Disclaimer: This is a non-profit tribute to the works of JK Rowling who created and, together with her publishers and licensees, owns the characters and settings elaborated herein.
A/N: Spoilers, knowledge assumed
First Year – Minerva
"You're just sour because you lost."
"You only won because Albus gave those brats fifty points each for rule-breaking. Now they'll never stop. Granger at least used to know better."
"Nonsense, she went looking for that troll, remember?"
"Crying her eyes out? Unlikely, Minerva. Gryffindor lies are so transparent. Only another Gryffindor would believe them."
Second Year – Lucius
"I suppose you thought that funny, Lucius."
"It had its moments, I suppose. But when He returns do you think He'll be impressed that you squandered His diary and His avatar to such little effect?"
"He did no better himself."
"Do tell him that. If you want to die screaming."
"Shut up, Snape."
Third Year – Draco
"Explain yourself, Mr Malfoy."
"Sir, everyone's saying you captured Sirius Black single-handedly last night but he escaped before he could be Kissed."
"He must have had help. Was it Professor Lupin? He's not at breakfast and no-one's seen him today."
"Professor Lupin was preoccupied last night. I imagine he's still baying at the moon."
Fourth Year – Voldemort
"So Dumbledore still has no suspicion?"
"No more than the day he hired me, my Lord. He thinks me his."
"And whose are you? You thwarted me with the Stone."
"My Lord, I beg pardon. You did not honour me with your trust. I thought him working for himself."
"Crucio – enough. Do better next time."
Fifth Year – Remus
"You must teach Harry Occlumency, Severus. Stop punishing him for our faults. It's been twenty years, isn't it time to forget?"
"Have the Longbottoms forgotten being Crucioed into oblivion? Or would they still scream at sight of Bellatrix?"
"Oh, grow up! That's completely different."
"Only because I don't need to see your faces to remember."
Sixth Year – Harry
"It's your fault! You wanted Sirius dead!"
"Respect, Potter! He died too soon. I wanted to fight him myself, alone, without his friends interfering. Then let the best man win."
"It wouldn't have been you. Ever!"
"Five points from Gryffindor, Potter. We'll never know, will we? He never dared to face me one on one."
Seventh Year – Hermione
Afterwards she wondered if he'd meant the compliment or had merely been finagling a Slytherin win.
"Tell me, Miss Granger, in the seven years I've taught you Potions have I ever asked you a question to which you didn't know the answer?"
"There – there may have been."
"Five points from Gryffindor, Miss Granger. For lying."
After the final battle – Albus
"Albus, you're the father my own never was but we both know I was never the favoured son."
"Severus - "
"It was Potter and Black in my schooldays. It's been Potter's son since. You'd have sacrificed any or all of us for his sake and I'd have obeyed for yours. I'm leaving now for mine."