Ok, so finding Sam/Dean x-mas themed fics is no problem at all.
The hard one is specifically finding ones that turn the ending of A Very Supernatural Christmas episode into wincest.

Whether it's pre-established relationship, or that night was the first time they acted on it in any way (kissing, if nothing else) is what I'm looking for. Morning after stuff would be nice, too.

Every time I see that episode, I'm all like "kiss kiss kiss!" :D