Ultraviolet by R.J. Anderson

Book 1 of 2 (Quicksilver is the companion novel)

Summary:

“Once upon a time there was a girl who was special. This is not her story. Unless you count the part where I killed her.”

Sixteen-year-old Alison wakes up in a mental institution. As she pieces her memory back together, she realizes she’s confessed to murdering Tori Beaugrand, the most perfect girl at school. But the case is a mystery. Tori’s body has not been found, and Alison can't explain what happened. One minute she was fighting with Tori. The next moment Tori disintegrated―into nothing.

But that's impossible. No one is capable of making someone vanish. Right? Alison must be losing her mind―like her mother always feared she would.

For years Alison has tried to keep her weird sensory abilities a secret. No one ever understood―until a mysterious visiting scientist takes an interest in Alison’s case. Suddenly, Alison discovers that the world is wrong about her―and that she’s capable of far more than anyone else would believe.

Opening Lines:

Zero (Is Translucent)

Once upon a time there was a girl who was special. Her hair flowed like honey and her eyes were blue as music. She grew up bright and beautiful, with deft fingers, a quick mind, and a charm that impressed everyone she met. Her parents adored her, her teachers praised her, and her schoolmates admired her many talents. Even the oddly shaped birthmark on her upper arm seemed like a sign of some great destiny.

This is not her story.

Unless you count the part where I killed her.