I've looked everywhere (went through the tags here and did a search and no luck), and I can't find this fic. The main thing I remember is that it's set around Christmas, and Jensen gets diagnosed with mono. I think Jared hangs around until Jensen gets better. It may have been a first time fic, but I'm not 100% sure.

I hope this rings a bell with someone. :)

ETA: Found! Link in comments.