Emma made her way into the house, chilled from the driving rain that was teeming outside. Hanging up her coat, she shook out her ebony hair, in the hopes of drying it quicker. She listened for a moment, looking for any sign of life in the grand old house. Silence. Her father was probably at work, and Sharon...well, any place other than where Emma was would be fine, for the time being. She shuddered as she thought of her stepmother. She had to be over forty, but the woman had been nipped, tucked and lifted so much, she could pass for a college senior, from a distance. At seventeen, Emma had the look of her late mother: thick, flowing black hair, pale, creamy skin, and bright blue eyes that pierced through a person when she looked at them. She knew that it bothered Sharon to no end to see her father spend any amount of time with her, almost as much as Sharon's very presence bothered Emma.
Sharon had been Emma's mother's home care worker. Her mother had been in a car accident when Emma was only five that had caused paralysis on her right side and severed her spine. her father had hired Sharon through an agency to help with personal care and housework. At first, she seemed like a sweet, personable person to most, except Emma. She had taken an odd dislike to her from the moment she stepped into the house. Within a year, her mother was dead, struck down suddenly by a reaction to medication; six months after, Sharon was her stepmother. In the twelve years that had followed, Sharon had tried endlessly to distance her father from her, suggesting boarding school, lying about her behaviour, even trying to accuse her of stealing from her. It hadn't worked so far, but Emma knew that it would only be a matter of time before Sharon came up with a way to sever her relationship with her father permanently.
*** I wanted to flesh this out more, but time constraints are going to force me to cut it short for now.
The plot continues as such, and I will post a full version when I get to complete it:
Emma finds evidence that her mother's death was intentional, just as Sharon walks in. They argue, and Sharon threatens her life, causing her to flee to the streets. Frozen, hungry, and determined to end Sharon before she ends her, she finds herself in an underground club, filled with some decidedly unusual people. She befriends a man named Hunter, who turns out to be someone sent by Sharon to kill her, but had a change of heart. Siding with Emma, the come up with a plan to expose Sharon for the black widow that she is. She and Hunter return to the house several nights later, intent on exposing Sharon's deceit to her father, only to walk in on Sharon attempting to smother him. There is a struggle, and Sharon escapes temporarily, wounding Emma in the fight. Hunter leaves in pursuit, leaving Emma to explain it all to her father.****
Attn ThatRPGuy: sorry it's incomplete, but I hope it gives you an idea where I would take it.