10 MORE Worst Betrayals In Horror Movie History

4. Ben & Violet to Caroline - The Skeleton Key

Oof, this one really hurt.

Directed by Iain Softley and written by Ehren Kruger, Skeleton Key revolves around a hospice nurse, Caroline, who's hired to care for a stroke victim, Ben. Over time, Caroline suspects Ben is being abused by his wife, Violet.

After finding paraphernalia in the attic, Caroline learns the house's former servants, Cecile and Justify, were hoodoo practitioners. Due to Violet's hostile nature, Caroline suspects she's using hoodoo to control Ben, giving the impression he's suffering a stroke. 

Basically, Violet is painted as a textbook villain while Ben is perceived as a helpless victim.

But as is often the case in stories like this, nothing is straightforward. Caroline ultimately discovers Cecile and Justify have repeatedly transferred their souls into other bodies to elongate their lifespan and currently reside in Violet and Ben.

At least for the time being. In the third act, Justify successfully places his consciousness into Caroline while trapping her mind inside Ben's paralysed and ailing body.

It's a devastating ending since Caroline suffered the worst possible fate imaginable because she unknowingly protected the very person trying to steal her life.