Dean and Cas have been sleeping in the same bed for quite some time. Nothing romantic, Dean was just worried about Cas. Since he fell, he would have trouble sleeping.
One reason to that was because he never really had to. As an angel, sleeping isn't necessary. Another reason was because he would get nightmares. Terrible ones. He told Dean about them sometimes, ones about his brothers and sisters killing him, some about the time he fell, some just about scary things his mind wondered to as it does for everyone.
So one night when Dean found Cas tossing and turning, crying and screaming in his sleep he couldn't just leave him there. He told him that he could sleep with him to feel safer.
They didn't touch when in the same bed. Dean is a flaming heterosexual, boobs and all that, so he didn't want to have any contact with a man in the same bed. Not that he was homophobic, he just found it a bit awkward.
They each had their side of the bed that they, mostly, stuck to. Cas had the right and Dean the left. However Dean mostly slept in the middle; leaving the ex Angel not much space, but he manages mostly.
However tonight the tables have turned. Dean was tossing in his sleep next to a wide awake Castiel. He couldn't sleep but didn't want to interrupt Dean's sleep with his problems. He put his hands behind his head and stared at the ceiling as Dean mumbled things in his sleep.
"Dad... I'm... Sorry..." Dean mumbled, each word getting louder. He was practically shaking by now, but Cas didn't know what to do. He wasn't familiar with this situation, so he let him carry on. When Dean turned towards Cas, he noticed Dean was crying in his sleep.
Cas was about to do something, shake him awake, but Dean shuffled towards Cas buried his face in Cas's chest. That took the ex Angel by surprise as he remembered the strict 'no touching' rule, but thought that if Dean broke it than it was okay.
He lifted his head slightly to let his left hand go and wrapped a protective arm around Dean, pulling him closer. He realised that Dean stopped mumbling and crying.
"Cas?" Dean mumbled, awake now. He looked around and noticed he was in Cas's arms.
"Oh... Sorry... Y-you put your head on my.. I thought it was okay.. I'm sorry," Cas said, he was worried Dean was going to kick him out and his nightmares would start again. He unwrapped his arm from around Dean, but before he could move it, Dean grabbed it and wrapped it around himself again.
"It's fine, Cas. Go to sleep," Dean smiled into Cas's chest as he heard his heart beating. Maybe he can rethinking the whole 'flaming heterosexual' thing in the morning.
"Okay," Cas said as he pulled Dean closer and shut his eyes. He was asleep in minutes, finding it easier to sleep with the hunter safely in his arms.
The next morning, Sam woke up first, as usual, and went to wake up Dean, but decided not to as he saw the two men safely asleep in each other's arms.
A/N
I don't really know where this came from but I just wanted a cute little one shot so here.