That took Sam by surprise. For a moment, she was still stuck on the theory that something was seriously wrong with him-- but a moment later, her mind caught up with the situation. Her eyes widened a little in surprise. "Oh," she said. "Sorry. I thought you were-- the one that was already here. When did you get here?"
Yet another version of Cas, and not hers. Christ. How many of them were there? In how many worlds did some version of her and her friends exist? All of them, maybe. Though, in an infinite number of universes with an infinite number of possibilities, there had to be at least one where she didn't exist at all. Maybe even one where she had existed and then, by her own design, had actually managed to convince her parents not to have her when she'd gone back in time, and thus erased her own existence.
Thinking on all of that too hard was going to make her head hurt. Refocusing on the situation, she noticed the way he'd wrapped his arms around himself and frowned in concern. He didn't appear to have been stabbed; there was no evidence of a wound made by an angel's blade. Was there another way for an angel to die? If there was, she'd not heard of it. Had he been human, she'd have guessed poisoning from the way he was clutching his stomach, but angels didn't get poisoned. "What happened? What's wrong?"
He had seemed uncomfortable with being touched, though whether that was because he was in pain or because she was strange to him, she didn't know. She didn't want to hurt him more, so she avoided that, but she took a slight step closer, to brace him if the need arose. With more determination than she really felt (mostly because she'd not had the most success at keeping her word in such situations in the past), she said firmly, "I'm not going to let you die."