Dean didn't know where it had appeared from - especially considering it was the middle of summer - but he wasn't sure whether to be glad for it, or to hunt down whoever had put it there.
It was probably Sam, knowing his brother.
The brothers and Castiel were staying at Bobby's house, working on a case in Sioux Falls, which Bobby had requested some help with.
What the elder Winchester had noticed was a piece of mistletoe, hanging over the entryway leading into the kitchen.
Unfortunately, Castiel was standing right below the Christmas plant, and, if Dean wanted another beer - which he was seriously craving right now - he would have to pass the angel.
There was also the fact that Sam was standing in the kitchen, and had caught Dean's eyes, directing him to look at the plant on the ceiling - reaffirming his suspicions that it was his brother that had set the whole thing up. This silent discussion took place after he had already noticed it, but it meant that there was no way he could pretend to have not noticed it now. And, knowing his brother, he would not let him into the kitchen without carrying out the tradition.
After another five minutes, the blond decided he wanted another drink so much that he didn't particularly care that he would have to kiss Castiel to get to one. Truthfully, he didn't really mind in the first place, but, if he was going to kiss the angel, he didn't want it to be forced.
But, Dean was not one to shy away from a challenge.
He strode towards the kitchen, stopped from fully entering the room by his brother's huge moose-hands.
Not needing an explanation, Dean turned himself, grabbed the lapels of the angel's trench coat, and pulled Castiel in for a kiss.
If it was going to be forced, he was at least going to make it good for the angel.
When he finally pulled away - a minute or so later - Cas was in a daze, a smile gracing his mouth, eyes flitting up towards the mistletoe.
The elder Winchester walked fully into the room now, to the fridge, and got two beers out. He held them both in one hand, and, with his other, grabbed the hand of his angel, pulling him out to the sofa in the living area, where he had been sitting before. He put both beers on the table, and looked Castiel in the eye.
All he could find in there was lust and adoration, so he had no qualms about kissing the angel again. And again. And again.
When Sam walked in on them, an hour or so later, they were cuddled against each other - Castiel enjoyed hearing his human's heart - watching a Christmas movie on the small television in the room.
The beers on the table were long forgotten, and Sam smiled fondly at the sight.
He wished he had been as genius as Bobby, who had been the one to put the mistletoe up.