Everypony knows Luna returned on the day of the Summer Sun Celebration. But she actually returned years before, one cold, snowy Hearth's Warming Eve at Canterlot castle... when Twilight unexpectedly came for a visit.

A somewhat unconventional Hearth's Warming tale: no pony lost in the snow, no Santa Hooves, no struggles to find the perfect present, no humbugs... just a look at how the celebration, by bringing us together, helps us find things we thought we'd lost long ago.

Also serves as a follow-on of a sort for the events of My Little Student, which was always as much about Celestia as it was about Twilight...