The Half-Blood Prince
Eileen Prince, later Snape, had always been a strange woman; Slytherin through and through, of course, but odd with it. There was an obsessiveness in her nature that made her more than usually ruthless. When it seemed that no man would have her for a wife, she set out to make a man marry her.
Tobias Snape, though unfortunately a Muggle, turned out to be a perfect candidate. A love potion slipped in his drink resulted in a one-night affair, which Tobias decided the next day would remain just that. But Eileen had planned for such an eventuality. It was more than just his propensity to drink any drink placed in front of him that made him a good candidate. He was an old-fashioned sort of man, with old-fashioned morals. When Eileen showed up at his door later, claiming to be carrying his child, they were married within the week. On their wedding night, she revealed two truths that soured their relationship immediately. First, that she was not in fact pregnant. Second, that she was a witch. When he refused to believe the full truth of the second one, she proved it by taking up her wand and making the pillows fly around the room. He hated her for the marriage she had tricked him into, but she terrified him. For a long time after that, she would be the tyrant in their relationship. Whenever his ideas contradicted hers, she would invariably win the argument by taking out her wand and toying with it, mock-playful. Tobias would stare at the thin strip of wood and gulp, his face going pasty-white with fear. He could never forget the bizarre sight of his pillows dancing about near the ceiling.
There might never have been a child but for Eileen's sudden longing for a son to carry on her magic. She had to use more love potions, but at last she could proclaim to her bitter husband that her son grew inside her. And so Severus Snape was born, treated as if he belonged solely to Eileen. Certainly Tobias wanted no part in the child, who from the beginning shared his mother's unfortunate features.
When Severus was young, just at the age when most children develop an obsession with the art that can be made while eating paste and making a mess, he found some of his mother's parchment and ink. Spreading the papers on the floor in his room, he stuck his pale fingers into the jar of ink. Using them as impromptu paintbrushes, he spread the ink over one parchment and then another in a fashion that many might term "modern art." When his mother came in to find ink spattered liberally over the parchment and the floor, she stood speechless for a moment. Then she began to yell. Phrases such as "ungodly mess" and "waste of good parchment and ink" came out, along with less pleasant things. Severus, who had really only wanted to make some pretty pictures for his darling mother, began to cry, which only made things worse. Eileen could not abide tears, and it was lucky for Severus indeed that he had never been a whiny baby.
It was not long after that when Severus began to understand his mother better, and his efforts to impress her soon paid off, in tiny, rare smiles and sparse words of praise. He stood straight, conducted himself well at the dinner table, and most of all he remained seen, but not heard. He was a sharp boy, and he had learned that to keep his mother happy it was best to be as unobtrusive as possible.
Sometime in those years, the relationship between Tobias and his mother changed. When he was seven years old, his father waited until his wife was asleep and snapped her wand in half. In the morning, when she woke up, she began screaming at him. But when he raised his hand against her, she fell silent. Thus a new era in the Snape household began. No longer was Tobias Snape the downtrodden one; now he was the tyrant. Eileen was no longer allowed out of the house; Tobias feared her buying a new wand, or enlisting the help of powerful friends. And whenever he had too much to drink, or when she angered him, he would smack her around while Severus cowered in the corner, helpless to save his beloved mother but too horrified to look away. Often his father would scream, "Sic Semper Tyrannis"—thus always to the tyrant—as if his wife's former domination of him gave him to right to leave bruises on her body. Later Severus would remember this, and him, with loathing. And always there was the helpless horror of watching the woman who was the light of his life, his anchor and protector, reduced to shielding herself as best she could as a man much taller and bulkier than she rained blows upon her.
And yet Tobias never turned upon him. Severus learned that his self-imposed unobtrusiveness, which he had developed to please his mother, also served to shield him from his father's abuse. And so he learned what, for a long time, he would regard as the most important lesson he had ever learned: Keep your head down and your mouth shut.
Of course, there were always his mother's lessons to consider when he thought of his father. His mother told him that Muggles were lesser beings than wizards, that his father was inferior to the two of them, who had magic in their blood. While he watched his father beat his mother, he also realized that even if a Muggle bested a witch or wizard, it was with pointless, artless violence. And he vowed that he would always live up to his heritage as a wizard.
Years later, when he wrote his identity inside his copy of Advanced Potion-Making, it wouldn't be his birth name. It would be his true identity, the one he had grown up believing was the only part of him that mattered: The Half-Blood Prince.