When Trevor possessed Elizabeth's body, she tried to fight it. Unlike many other women he possessed in the past, it didn't happen quietly. Her body jerked and shook as his spirit entered her. But all of her fighting did no good. In only a few seconds, he had full control, leaving Elizabeth trapped in the back of her own mind. Whatever he finally chose to leave, she'd have a dream-like memory of whatever he did with her body. Of course, considering how much he was already enjoying being her, he might not leave for a very long time.