A/N Takes place between Supernatural season 5 episode 6 and season 5 episode 5. This is based off of a headcanon I saw that Dean has nightmares about hell and Cas sits on the bed by Dean and calms him down by speaking in enochian. Enjoy!
Sam couldn't sleep. He lay in bed, staring up at the ceiling. Every time he closed his eyes he saw himself fighting with Dean. He heard Dean's echoing voice say he couldn't trust him anymore. Sam knew Dean still didn't quite trust him, not as much as he had before. He knew Dean was trying to move past what had happened between them but it still hurt. The way Dean glanced at him sometimes, as if unsure what Sam would do. It didn't help with all the guilt that already weighed him down.
Sam's mind wandered to the colt and he began to think up theories of where it could be. Finally, Sam felt the releasing sense of sleep closing in. He lay in the silence. Sam shifted. It was almost to quite. Sam looked over at Dean. Dean lay still in his bed. That wasn't right, Dean always moved around on his bed. The light coming through the motel window let Sam see Dean's face. His eyes darted this way and that under his eyelids.
"Sammy. Somebody help me."
Sam immediately detected the panic in his brothers voice and stood, intending to wake Dean from his nightmare. Just then, he heard the sound of fluttering wings as Cas appeared at the side of Dean's bed.
"Don't worry Sam, I got this." Said Cas. He sat down on the bed next to Dean and began to speak in enochian, rubbing soothing circles on Dean's back.
Sam watched in amazement as Dean gradually relaxed, Cas continued speaking in enochian until Dean was sleeping deeply and peacefully.
Sam motioned for Cas to follow him outside so they wouldn't wake Dean.
"That was.."Sam trailed off, not knowing what to say.
"He experiences nightmares about his time in hell. More like memories really. It has been happening ever since he came back."
"Yeah, I noticed but I thought they stopped." Said Sam.
"They mostly have, but he still gets them occasionally. When he does he sometimes prays for me unconsciously and I know he's having a nightmare. When he does I come help."
"Thank you Cas. Is there anything I can do to help him?" Asked Sam
"If you let me know whenever you notice that Dean is having a nightmare that would be helpful. Other than that I don't really know."
Sam nodded, "Sure thing." He said with a yawn. "I'm gonna try and get some sleep now. Night Cas."
"Goodnight Sam." With that Cas was gone. Sam went back into the motel room and tried to sleep but couldn't. Instead he worked on research, periodically checking to see if Dean was okay.
Dean woke and stood up. He looked over at Sam who was asleep at the table with his computer in front of him. Dean smirked and shook his head. "Stayed up all night doing research again, huh." He muttered to himself, making a mental note to make sure Sam got more sleep. Dean got ready for the day then grabbed a cup of water and splashed it on Sam, being careful not to get Sam's computer wet.
"Dude!" Sam said.
Dean grinned. "Come on Sammy, up and at em'. We got a dead body to visit."
Five minutes later agents Page and Plant walked into the local morgue.
From then on Sam stayed up for a couple hours into the night, doing random stuff while keeping an eye on Dean. Any time he saw that Dean was having a nightmare he would pray to Cas, who would come, calm Dean down and then leave.