There was a human inside of little Barty Crouch, Jr. It was just very, very far inside and it was very small. It was, perhaps, more stimulated by Regulus than by anything else it had ever been called forward by in a long time. There were things about that that scared Barty. So he suffocated the thing and threw it back in its closet, far away from everyone else's reach.
And thus he came to be perched over a bound, naked, scared & angry girl with a smile on his face.
Quickly, it popped into Barty's head that he had forgotten his book downstairs. He blinked, confused for a moment.
And then Meaghan's rage grew and she thrashed towards him. Barty swiftly retreated - on his knees above her. He glared down at her, feeling at once angry that she had almost taken advantage of his wandering mind and split his lip again.
Violently, he undid his trousers and pushed himself into Meaghan. Some might wonder at his ability to get an erection at such a time. But, there was nothing like power to turn someone like Barty on. - It was difficult, really, getting into the girl. She didn't want it, and it was almost as if his penis knew that and didn't want to go into hostile territory.