Caught

Isaac and Emily had been dating for several years when a freak accident from the explosion of one of their neighbor's inventions caused Emily to swap bodies with Isaac's mom, Beth.
Emily was secretly excited to own Beth's body, which was so much curvier than her own, though she played it down for Beth's sake. Still, Isaac caught her enjoying herself several times, her fingers stroking her heavy breasts as she fingered herself. Isaac stayed hidden in the hallway, peeking in to watch her. It was so strange watching his mom's body with his girlfriend's mannerisms. Strange but hot.
The day she'd caught him watching her he'd wanted to get caught. She invited him in and he approached eagerly, his hands greedy for his mom's heavy swaying tits. His mouth found hers and they kissed, before tumbling naked into bed.
Isaac spread her legs and plunged into her wetness, sighing as he entered her heat, feeling her slick canal surrounding him. It had been so long since they'd had sex. The way she moved and gasped and moaned was all Emily, even as the wet, warm pussy he slipped inside was his mom's.
He leaned forward and licked her tremendous breasts until her nipples stood to attention. He thrust in deep, emptying himself into her with a quivering release and she took him in, her own hands back to her tits, coveting the body she now owned.
They tried to sneak down the hall to the bathroom but when they opened the door Beth was standing in the hallway. Emily just laughed, embarrassed and amused as she grabbed her boyfriend's cock.
"Yeah, we're having sex now," she admitted, as Isaac stood behind her, horrified. "I figured this is my body so...Isaac seems happy with it, don't you babe?"
She kissed him and he wrapped her in his arms, enjoying her curvy body, the way her tits pressed against him. Beth glowered at her body kissing her son, not missing the cum dripping down her former body’s thigh and knew what they’d been doing and would do again.
But there was nothing she could do. They were stuck like this and they might as well enjoy it.

A demon builds his power by possessing people and changing their bodies and minds to suit his needs in The Devil You Know, on Smashwords, Amazon or wherever ebooks are sold. Preview here.