The first time he felt it, he thought that he might be imagining things. He was a hunter, after all, and his senses were going to be slightly over-sensitive from time-to-time. Nothing to worry about.
But then it happened again.
He jumped this time, turning a full one hundred and eighty degrees, scanning the motel room for any signs of not-natural beings.
Y'know, besides the angel that was standing beside him. And his brother, who's hair was so long, it definitely couldn't be classed as natural.
When he didn't see anything, he turned back to face his companions, who were looking at him, confused, but amused.
"What was that panic attack about, Dean?" Sam asked, a smirk threatening to pull at his lips.
"Uh, nothing. Thought I felt something, but…" the blond was still a bit twitchy.
"But what?" Castiel's head tilted sideways, like it always did when the angel was confused.
"Nothing. Doesn't matter." the elder Winchester muttered, looking down, embarrassed.
Sam and Cas shared a secretive smile.
The third time it happened, Dean didn't panic. He did look pissed off, though. His hand slammed to the back of his neck, as if to catch whatever had been brushing against the back of it recently. Needless to say, he was unsuccessful.
The rest of the day, a muscle in the blond's cheeks twitched, and nasty snarl on the man's face, anger radiating off of him from a mile away.
When it happened the fourth time, he was just waking up from a peaceful sleep. He took comfort in the touch, and, when he didn't react, he felt the sensation again. And then again.
"Feels like a feather." Dean murmured, trying to bury his face back into his pillow. The realisation washed over him like a wave. He sat up abruptly, and noticed the angel standing right next to his bed. The smiling angel. "Fuck you, Cas!"
"It was your brother's idea, incase you were wondering."
Castiel looked worried that Dean was going to kill him. It was somewhat endearing, considering that the hunter would never be able to land a punch on the angel, without hurting himself more than it would hurt Cas.
Dean resorted to throwing his pillow at his sleeping brother. When the younger Winchester woke, Dean yelled a 'fuck you, Bitch!' to him, and got a miss-aimed pillow thrown back towards him.
Castiel watched the scene in amusement, shaking his head at the brotherly banter.