You are the only son of a leading family. You are attractive and popular, and everyone agrees that you will go on to great things.

You lie awake at night and attempt to justify yourself and your family. Your existence, your fortune, your actions.

You are usually unsuccessful.

You come to a decision: when you return to school, you will ask Lily to marry you. Quickly, before she can meet someone better, someone untainted by pure magical blood.

Before you can lose your nerve.

You have an idea, that marrying a woman of no wizarding family will somehow cleanse your bloodline. A clean start.

You'd take her name, if you thought you could.

Your father is silent for the rest of the holidays. The night before you return to school, he summons you into your office. On his desk, he has Lily's school records, and other documents, his investigations into her family.

He attempts to forbid you from associating with her. Words are exchanged.

You leave the next morning, swearing never to speak to him again. Your mother hugs you, and quietly reassures you that this time, you are doing the right thing.

At school, you do not speak to Snape, and he does not look at you. He treats you as if you are worthless; privately, you agree.

Occasionally, you wake shivering with the memory of his mouth, and his teeth on your skin.

Once, you kiss Lily, and strain to capture an echo of brandy and bitterness in her mouth. When, in a moment of passion, her teeth find your shoulders, you almost lose control, and the bruises on her skin are a stark reminder that she is smaller and more delicate than Snape.

Shortly before you finish at Hogwarts, Snape's parents are killed by Aurors.

Few people are sympathetic.

Six months after you leave school, your family are killed. The Dark Mark sails over the house, but curses more painful than the Killing Curse were used to kill your parents.

You survey the damage, and leave without speaking.

You cannot approve of this, you cannot allow this, but you cannot blame him.

You saved his life, once, and that made you responsible for him. And you failed. You will take more risks, move on to greater acts of heroism, and you will half-unwillingly survive them all. You will make restitution, if not to Snape, then to the world.

You will try to be a better person.

Sometimes you will succeed.