Leah

Leah is a mysterious phantasm of a pathetic man who lost his peace of mind, name was Ryan White. The fact that apparently turned him maliciously crazy was, nobody could see her but him.
Ryan White eventually turned out to be a disgrace of the White Family.
She sounded like his hallucination, but she looked like the younger self of his soul sister from his neighborhood, Ella Brown, who only existed till the period of his high-school.
A certified lover boy killed his romantic era after losing his soul sister for good. But Leah, afterwards, not only commemorated Ella, but also turned the rest of his life into a nightmare of regrets, through not letting him sleep at night and making him suffer the sexual tension. Not only she erotically tortured him without letting anyone acknowledge her existence, but also provoking him to look for Ella's daughter, Flora Brown, who was long gone mysteriously.
So who, or what was Leah?