Disclaimer: I do not own any Supernatural characters. They belong to Erik Kripke.
The first time Dean fell asleep in Castiel's lap was in Purgatory. It was the night after Dean and Benny had finally found Cas. They were camped out in some dark cave by the river. Benny had volunteered to take first watch and had settled by the entrance of the cave. This left Dean alone with Cas.
"I'm glad we finally found you, Cas," Dean mumbled happily, nudging Castiel gently with his finger. Cas, however, looked anything but glad. His face was scrunched up into lines of worry and tension, and his eyes were anxiously darting around. He didn't seem to have heard Dean.
"Cas?" Dean asked again, gently shaking Castiel's shoulder. Cas's gaze finally landed on Dean and he said,
"Yes, Dean." It wasn't the response Dean had been hoping for, but he let it go. Dean sighed, and decided to familiarize himself with his surroundings. Of course, they had checked the cave prior to entering it, but this was Purgatory and you could never be too careful.
He and Cas were sitting on the dirt floor, their backs supported by the cave wall. The hard rock was digging into Dean's shoulder blades. A few months ago that would have made Dean uncomfortable, but now he was used to the roughness of Purgatory.
Despite the fact that they were probably surrounded by monsters, Dean felt at peace for the first time in months. He had finally found Cas. After almost a year of searching, he had his angel back. Unfortunately, his angel didn't seem very happy about that fact. Dean couldn't exactly put his finger on what was bothering Cas, and it irritated him. Cas was obviously struggling with something, but whenever Dean asked, Cas just vaguely said something about the Leviathans following them. Dean didn't believe him.
"Hey Cas," he said, "I think I'm gonna crash." Castiel simply nodded in response. Dean sighed out of frustration. Clearly, Cas wasn't feeling very talkative. Well, Cas was never very talkative, but he seemed unusually reserved tonight.
Purgatory had not been kind to Dean. His body ached with bruises, cuts, and several other injuries that would have had Sam puking if he were here. Oh god, Sam. Dean had barely thought about his brother since he was zapped into Purgatory. There was something so surreal, and pure about the place that made Sam and everything else about that world seem like a dream.
Dean could feel his eyes drooping as they traveled around the cave. He felt like trying to keep them open was like lifting 200 pound a sigh, he let them shut, and almost smiled in relief. He had barely let himself sleep for more than two hours at a time in Purgatory since he didn't exactly trust Benny to keep watch because the guy was a frickin' vampire. But now Dean has Cas. Now, Dean had an angel to watch over and protect him. So for the first time in a long time, Dean let his exhaustion take control over his body, and was out like a light.
Castiel was contemplating his next move when Dean's head came to rest on his shoulder. He automatically stiffened from the touch, but relaxed after a few seconds. He felt horribly guilty for leading Dean on like this, for giving him a false hope. This wasn't supposed to happen. Dean wasn't supposed to find him.
Castiel sighed, and ran a hand through his hair. He didn't know what to do now that Dean had found him. It doesn't change anything, Cas thought, you still have to go through with the plan. But Cas didn't want to go through with the plan. Not if it hurt Dean. But Castiel knew that he had to pay for his crimes, no matter the pain it caused Dean.
On his shoulder, Dean mumbled something incoherent, and buried his head into Castiel's dirty trenchcoat. Cas winced at the angle that Dean was sleeping. It looked very uncomfortable, and Dean was bound to have a cramp when he woke up. So very gently, as not to wake Dean, Cas lowered the fatigued hunter onto his lap. Dean grunted a little in his sleep, and turned his body so that his head was completely swallowed by Cas's trenchcoat. The sight of Dean Winchester curled up in his lap made Cas smile.
"That's funny," drawled a Southern voice from the cave entrance, "I ain't never seen him sleep so soundly in this place. He must trust you, which is funny because I've heard that you betrayed him," It was the vampire, Benny. The smile disappeared from Castiel's face.
"He's just tired," Cas responded coldly. Benny shrugged, and walked back to his spot near the cave opening. Cas absentmindedly ran his fingers through Dean's hair while trying to sort out his thoughts. It was going to be a long night.
When Dean woke up, the first thing he saw was a cream colored cloth in his face. He knew instantly that it was Cas's trenchcoat because it smelled like the angel: a mix of dirt, blood, and some sweet scent that seemed to follow Cas around. Groaning, Dean blinked rapidly and twisted his body around to see where his was. He looked up, and found Cas staring down at him.
"Son of a bitch!" Dean exclaimed, and bolted upright. His forehead connected with Castiel's and a dart of pain shot through Dean.
"Ow. Sorry, Cas," he groaned, and Cas simply nodded. "Uh, Cas, why was I sleeping in your lap?" Dean asked. Cas shrugged.
"I thought it would be more comfortable than my shoulder," Cas responded, and Dean's mouth hung open stupidly for a few seconds. From the corner of his eye, Dean could make out Benny smirking.
"Oh, um, ok. Yeah, I guess that's a valid point," Dean choked out. Cas simply stared at him, and Dean stared back. They stared at each other for a good few seconds before Benny broke the silence.
"Alright, you two lovebirds about done?" He asked, drawing out a blush from Dean. "We gotta get moving." Dean nodded.
"Of course. Let's go, Cas." And they climbed out of the cave, Dean holding his sword menacingly on his hand, ready to take on the monsters.