There was more than enough hatred inside of William Wood to make his first Unforgivable successful. Writhing in pain, Hermione couldn't keep her promise to herself that she wouldn't scream. Inexperienced casters of that spell could be highly dangerous. Stuck in the same position because of the rope, she didn't have much of a chance to move around. Sharp pain inside her skin indicated that she'd broken at least a couple of bones. She might have broken more if he didn't let up soon after starting. He didn't have the stomach to keep up the steady stream of Dark magic required to make that spell work. Few did.