In the Late December
by Greg van Eekhout
Strange Horizons: Original • Kindle-friendly ((The Kindle-friendly version is NOT hosted on my site; this is a CGI script that filters the more annoying framing HTML from the story text. You can still save the filtered HTML and convert it for your Kindle (with some help from Amazon). And remember: don’t distribute this thing.))
And even unto the heat-death of the Universe, Santa perseveres.