Theo winced to hear Greg's reasoning because in his head Snape - or the Snape of twisted dark thoughts in his head anyway - wasn't who Theo would want in charge of their safety. He made a soft little noise of discomfort and shifted a little, about to voice his concerns when Greeg went down in the snow. He watched Greg bare his feet, slightly worried by seeing them so vulnerable which again made him just want to grab Greg and run for it.
He barely winced as Greg slipped his warm socks over his own feet, wriggling his sore and numb toes a little. He bit at his lip, unhappy at the sacrifice that Greg was making just for him, but he reached out to take hold of Greg's arms and get to his feet, a little unsteady. "I can't find my wand. We should cast so that they don't hear us. We can't be heard Greg... can't..." he shook his head and took a careful step, but it could have been because he was reluctant to make any sound as much as because his feet were almost useless.