This almost became a double, but I thought I'd play by the rules this week. yes it's meant to read Destiel-y.
He heard Dean's anguished cry for him, and Castiel homed in on that distressed sound and was at Dean's side in an instant.
At first he was confused, Dean lay in a bed, appearing to sleep peacefully, but upon closer inspection, Cas realized he was having a nightmare.
"Cas…Cas…" he whimpered in his sleep.
A Purgatory dream then. One of the ones where Dean searched desperately for Castiel's whereabouts and couldn't find him.
Cas gently touches Dean's forehead, and it works like a charm, the man's breathing and racing heart slowing instantly, as he moves in to more peaceful dreams.