Your mom had donated her body upon her death. Her mind was gone but her body was intact for the doctors to transfer someone else into. You'd come to terms with that.
What you hadn't been prepared for was that they transferred Lucy, your ex-girlfriend, into your mom's body. You were there when she woke up, blinking groggily around the room. Her eyes focused on you and they narrowed.
"What are you doing here?" She asked. "And why does my voice sound different."
You don't blame Lucy for hating you. You were the one who dumped her after cheating with her best friend. Still, it's your mom's body and you promised her you'd help the future owner adjust.
You explain what happened and who she is now. She looks down at herself, poking her new body, feeling her face and hair.
"Not bad for an old broad," she says, wiggling her fingers. She pulls the neck of her hospital gown up and looks down at her chest. "Not bad tits, either. My boyfriend will probably love these."
You try to apologize for how you acted but she wants none of it. The look she gives you, one of disgust, written across your mom's features, is heartbreaking. She orders you out of the room and when you try to protest she threatens to yank down her top to expose her tits and then scream for a nurse
You leave. To you, it's still your mom's body, even though the new owner is nothing like your mom. You hope Lucy will be able to adjust.
A college student discovers the ability to hop into people's bodies, and uses his new power to take over his cute crush and explore her life in How I Became a Hopper, on Smashwords or Amazon.