A smile flickered over Cas's face to match Dean's, although he still didn't understand, even if Dean seemed to think so. He let it go in favor of studying Dean's intriguing expressions. He tried very hard to hold still, hands tucked close near his chest. If he stretched out, his feet would tangle with Dean's. It wouldn't be so bad, would it? If he were to touch? Dean seemed to really like hugs lately. He could slide over and curl up close to Dean, and never mind if the closeness made his body temperature and heart rate increase slightly. They did not bother him, really.
Castiel only realized he was reaching over when his fingertips brushed Dean's torso under the blankets. He stilled again, still watching Dean's face. "I don't know," he said, "Dreaming is a mortal thing. Your brain still... firing synapses and sifting through worries and hopes and memories... You know, every face in a dream is one you've seen before somewhere. Not just friends, or family, but strangers as well. People you crossed paths with only once in the waking world..." He trailed off. His fingers were curled into the soft cotton of Dean's shirt. He kept his gaze steady.
"I don't know what I might dream about..." he mused, voice a little distant. It was a lie, he knew as he watched Dean. At least, he knew what he would like to dream about.