"Don't leave me." Sam felt so small, begging Cas to not leave him alone. He wasn't weak, and yet...He wasn't strong enough to carry this burden alone. There was no relief from it, though Cas could pull him out of the dreams, he couldn't prevent them from happening.
He grabbed at Cas' hand. It was impulsive, he didn't think about it before he did it. He became aware of it only after it was done. "That's all I ask. Just don't leave me alone."