So much AWWWW for the hand-holding! Loved Castiel turning the usual confusion on its head (of course humans don't make sense!) and I particlarly adored the image of Dean standing rigidly holding Castiel's hand like he is reaching for some personal best. This line is perfect:
“Just trying something. Research. Like everyone’s always telling me...”

Bwwahhaahaha! Yay fluff! Thank you.