Katniss stared back at him. It took her a moment to realize what he meant. He was so cold that he must be numb, and the blankets weren't helping. They couldn't really reflect back heat if he wasn't giving any off, which he really didn't seem to be. How that was possible, she didn't know. But if he could feel her body heat...
"Here," she said, starting to unwrap the blankets. "I'll get under there with you."
It was a logical solution, and she needed to warm him up as quickly as possible, before the cold damaged his body. She managed to get them undone enough to step close to his side, pulling the blankets back around them both. He was freezing, and she couldn't suppress a shiver, but her body heat seemed to be winning out over the cold, so she stayed where she was. After making sure that he was holding onto one side of the blankets, and the other side was comfortably in her hand, she slipped her free arm around his waist. "Come on, you need to see a doctor. And you should move around, anyway."