Zero

Alice, a sweet and smart girl without many friends, created imaginary friends named after numbers. She eventually forgot about her first friend, Zero. After witnessing her parents' death in a car accident and being adopted by Mr. Rogers, Alice faced physical abuse and was forced to do manual labor for him. The person was bullied for years and finally snapped when someone pushed her down the stairs, responding with a savage beating. A girl violently attacked someone, stopped when yelled at, and ran home. She couldn't explain her actions and became reclusive after being expelled. A mysterious voice then emerged from her mouth saying "We're best friends, forever." Alice was beaten and lost consciousness. Upon waking, she learned of a man's death resembling her own abuse. The mysterious voice returned, causing another fainting spell. When Alice regained consciousness again, she had transformed into Zero and killed those who knew her former identity before fleeing to the woods. Alice was once a quiet, polite girl seeking love and acceptance. However, her abusive upbringing made her more anxious and anti-social. Her only friend was Ann. After Zero took over Alice's body, she became a demented sociopath who killed Ann without remorse. Before Alice was possessed by Zero, Alice was as a fair-skinned teenage girl with long, curly, brunette hair and pale green eyes. After snapping and Zero taking over her body, she took on a very skeleton-like appearance. Her hair and skin had turned paper white, the pigmentation of her eyes had faded to gray, with dark makeup/eyebags surrounding them. Zero is usually seen wearing a black sweater or tank top, dark gray shorts or jeans, gloves, black and white striped socks, and scarf, and brown boots. Her weapon is a sledgehammer. Zero is supernatural in a sense, as she possesses superhuman levels of speed, stealth, and strength. Zero is also very intelligent, as she's able to easily sneak into someone's house and murder them without being detected. And with her incredible strength, she's able to carry and run with her large sledgehammer without any trouble. She is 23 years old now.

A dark alley at night