Harry Potter: The Partner Bound by Snape's Soul Contract

The whole school complains that Snape plays favorites and only cares about Slytherin. Nobody knows that every Thursday afternoon, he locks the dungeon and teaches me alone. He teaches me Blood-Replenishing Potion, Wolfsbane Potion, and advanced potions, guiding me every step of the way; he passes on everything he knows about the Shield Charm, Nonverbal Spell, and Patronus Charm. He teaches me like this for five whole years. I improve a potion and save Lupin, my handwritten notes become the DA's official textbook, and when Bella comes to capture me, I raise my hand and silver light explodes, scaring her off! In the shadows, Snape, usually so cold and grim, lets the corner of his mouth curl upward. His voice is proud and indulgent: “She learned from me, of course she's brilliant.”