The sound of Naomi's voice, telling him not to struggle.
The buzz of a drill.
The feeling of it boring into his skull as he screamed and thrashed.
Castiel awoke to the sound of a scream, and his door was burst open in a matter of seconds.
"Cas! What's wrong, what happened?!" Dean was at his side in an instant, one hand on his shoulder and the other brandishing a knife. He wasn't completely dressed, only wearing a pair of boxers and a t-shirt, which gave away that he had been dead asleep only moments before-hand.
Castiel shook his head slowly, trying to clear the sleepy fog from his mind. "I don't know. Who was screaming?"
"You were." Dean frowned and relaxed his posture slightly. "Shit, Cas. I thought you were being attacked or something."
"I don't believe I was, I was just-" He stopped, his dream coming back to him in a rush. Castiel sat straight up and looked around wildly. "Where is Naomi?! She was here, she was just here-"
"Cas?"
He looked up at Dean, eyebrows furrowed. "I don't understand, Dean, she was here. I know she was. She had her drill and she was- She was rewiring my head again."
Dean sighed and sat down next to Castiel on the bed. "Cas, she's not here. That's impossible. I mean, last time you saw her she had a drill in her brain, right?" Castiel opened his mouth to protest, to assure Dean that what he had seen was completely real, but Dean just continued. "And even if she did live through that, Metatron cast out all the angels, remember? There's no way Naomi would be an exception. She's not a threat anymore."
"Dean, you don't understand, I saw- "
Dean gave Castiel's shoulder a pat. "It was a nightmare, Cas. Welcome to humanity."
"I- You mean... That wasn't real? That was in my head?"
"Pretty much, yeah."
Castiel looked down at his hands. "You mean that you- I mean- us humans have to deal with this? Hallucinating about our greatest fears?"
Dean smiled just a little. "Yeah. Sucks, right?" He moved to stand back up. "Try to get some sleep, alright Cas?"
Castiel grabbed his arm before he could get back up. "Dean."
"Yeah?"
Castiel frowned, staring at Dean's face. "I don't want to be alone."
"Jesus. Cas, I'm not your babysitter-"
"Dean, please." The look in Castiel's eyes was that of desperation, mingled with fear. "What if she comes back? I don't want her to come back. Please."
Dean stared back at him, then turned his eyes to the ceiling for a brief moment before nodding. "Fine. Make some room."
Castiel scooted over, and Dean lied down next to him. "This is the only time I'm doing this."
"Fine," Castiel replied quickly as he gripped Dean's arm again. Something about it was oddly comforting.
"Good." Dean closed his eyes. "Now go to sleep."
Castiel nodded and closed his eyes as well.
"Cas."
"Yes, Dean?"
"Good night."
Castiel relaxed, his expression softening.
"Good night, Dean."