Christmas.

Castiel didn't fully get it but he saw no harm in trying. At least trying for you. He knew the bare minimum of it all thanks to Dean and Sam; gift giving, spending time with people you love, and decorating.

He could do that.

So here Castiel was, helping you put up some tinsel around the bunker. Again, he didn't understand why but he enjoyed it. He enjoyed getting to spend time with you.

"It's very bright." Castiel stated the obvious as you hung up some of the tinsel.