I wrote this fic a couple of months ago, inspired by a question in a LJ community: "What do you think happened to Snape's parents?" Here's what I came up with; maybe a bit too angsty/tragic, but there you go.
I stayed as close to canon as I could; hopefully it all works well. The piece hasn't been beta'ed, so all mistakes are mine.
Rated T for violence (nothing too gory, though) and character death.
Disclaimer: Everything you recognise belongs to JKR; the rest is mine.
I hope you enjoy. Any comments (on spelling, grammar, characterization...) are welcome. I accept both signed and anonymous reviews.
"You stupid, useless woman! That's all you're good for!"
The hook-nosed man sweeps the table with his arm, throwing all the little jars on the floor and spilling colourful liquids all over the place. His fist is still clutching an old, light blue shirt.
"You spend hours playing with these damned toys, but you're above washing a bloody shirt, right?"
The woman takes a few steps back from him, frightened to silence.
"It's all so much more important than keeping your house and your husband's clothes clean, isn't it?"
He approaches her. His breath reeks of alcohol, and she inadvertently cowers away.
"Can't tolerate being near your husband, can you? Well, can't blame you, since he's so angry at you! But you know why he's angry? Because you're a no-good woman, that's why! A cursed witch, that's what you are! A waste of space eating from the bread I struggle to bring home!"
Five-year-old Severus is slumped back in a corner, crying as he watches the fight. It's not the first time he sees his father mad, but it seems like every time is worse.
"Curse you!" the man shouts and his smelly spit douses his wife. She hides her head behind her arms and lets out a whimper. He then throws the crumpled cloth at the boy.
"What the hell are you crying for? Shut your mouth before I make you!"
Little Severus runs to his room at once, unable to stop his tears.
"You cursed woman! I'm sick of you!"
Fifteen-year-old Severus is sleeping in his room. He is used to his father's drunken shouts, so they don't disturb his sleep. What jerks him awake, though, is a sound of two things violently crashing.
He snatches his wand and runs out of the room. It takes a moment for his eyes to get used to the light, but when they do, he sees his mother slumped against one leg of the table, unconscious, the back of her nightgown drenched with blood. Horrorstruck, he looks at his father; he's red-faced, panting and staring dumbly at his wife as though not understanding what has happened.
In mere moments, Severus's horror at the sight turns to hate; his blood is now boiling. He raises his wand at his father and shouts, "SECTUMSEMPRA!"
An invisible sword slashes across Tobias Snape's body; the force of the spell throws him back and to the floor. He doesn't even make a sound as he's hit; he doesn't yell, cry, or threaten. He just lies on his back, silent, with fear reflected in his eyes and blood streaming out his torso.
It takes Severus a minute or two until the shock wears off and he can think rationally again. He runs and kneels close to his mother.
"Mother? Mother?"
But she doesn't reply.
He picks her head up and looks for the wound; it's in the back of her neck. The blood trailing from the corner of the table betrays the weapon of her injury.
He doesn't know if it's because he's not yet in the mental condition to perform magic, but none of the spells he casts with his trembling wand-hand seem to have any effect on his mother.
By the time the police arrive, Severus is holding a bloody knife in his hands. He claims to have attacked his father with it after seeing what he did to his mother, but everyone is convinced that he's trying to protect his mother, and that Eileen Snape was really just self-defending with it. Severus Snape has always been too much of a silent and timid boy to be considered guilty of such a violent act. Tobias Snape nods in agreement with the policemen's train of thought, and the matter is settled quickly and painlessly for his son.
A nice policeman takes Severus to the corner of the room and calmly explains to him that there's nothing he can do now to protect his mother, but that he doesn't need to, anyway. She would certainly appreciate her son's intention, but he doesn't need to ruin his life for the mistakes of his parents.
Severus is just barely listening, when he sees his mother being taken away, covered with a white sheet.
"NOOOOOOOO!" he screams, and runs to the stretcher, but a couple of men hold him back. One of them advises him to go to sleep for now, and tomorrow he might want to pack his things and move out with other family or friends. He is friends with Lily Evans, isn't that right? Maybe he could spend some time with them?
But no. He wouldn't tell any of the policemen that, but he's had enough of Muggles. Instead, he just says that tomorrow he'll be moving back to his boarding school, and when summer rolls again, he'll see where he can go. The policemen seem to be satisfied with that solution.
Tobias Snape is sent to prison. His sentence is slightly reduced because of his drunken state at the time of the murder, but he doesn't live through it anyway; ten years later, he will die in his dirty cell, sickly and alone. He will never see his son again and will never talk about the big scar across his torso; who would believe the truth about how he got it?