Dean almost didn't have the heart to tell Cas that he was going about it the wrong way. The poor angel had almost no sense of anything on Earth anymore.
Tying a tie was the least of his problems at least.
For Dean, it was hysterical to watch his brow crease in confusion and frustration. To be honest, Dean was willing to do it for him, but Castiel hadn't asked him yet. Dean wanted to see how long it would take him to ask for help. Dean was losing his patience. It was cute the first couple of times that Cas managed to make it resemble Dean's knot, only to have it unravel in his hands the next second.
Castiel's concentration face was turning steadily into a pout. He had spent nearly half an hour trying to learn how to do it. Eventually he looped it around the bed post, "I do not need a piece of cloth around my neck," he stated simply while Dean laughed.
"I fail to see what is so funny, Dean, I apologise."
"Dude, let me help you, Jesus. It's not that hard to ask," Dean worked for several seconds on the tie before tightening the knot under Cas' collar.
"There," Castiel stared down at the knot for a moment,
"Thank you..."
"Hey man, no problem. We do have an appointment to keep so-"
"You mean an interview with someone who may have insight on our current case, under the guises of FBI agents?" Dean frowned,
"Well yeah..."
"Have I offended you in some way?"
"No, man. Just, don't talk about our jobs to anyone else. I have seriously got to teach you how to lie."
"Bearing false witness is a sin..."
"Yeah well... You're a... Sin..."
"..."
"Let's just go."