I'm not supposed to be in the dark
(Book)

To help her best friend-turned-enemy Derek, who's possessed by a ghost, seventeen-year-old Aria must reestablish her link to the afterlife with the help of a new love to remove the lost soul from Derek's body or they could lose him forever.

Thanks to a special tea brewed by her grandfather, Aria Cayetano's connection to the spirit world has been severed. Until a decades old rosebush suddenly dies across the street, convincing Aria that something supernatural is happening in her neighborhood. The rosebush is on her ex-best friend Derek Johnson's lawn. They've been apart for years now, but Derek has been acting strange for weeks now. When Derek begins speaking to her again, Aria discovers there's a ghost inside him. It will take his life if it doesn't find what it's searching for-- but saving Derek means tapping into whatever the tea has buried inside of her. -- adapted from jacket