Ice herself had very little interest in being bound, and she reasoned that if he meant to break their arms, he'd have to come inside. Two of them, one of him ... and she thought they could stand a chance against him.
Arms were awfully hard to break, after all.
Reasoning that he had more interest in Kate than in her, Ice remained where she was on her bed, watching the interactions with some passive interest. Whatever she might or might not have been feeling wasn't reflected in her expression, her posture, her breathing. She looked for all the world like she was simply waiting for a movie to start.
But she was watching all of it ... watching him, mostly, to see what his intentions were, and to keep an eye for an opening. She could cooperate, sure, but as of that particular moment, there was little incentive to do so. So she'd follow Kate's lead for the most part, unless something else presented itself.