One of my all-time favorite Pony fics · 6:12pm May 8th, 2013
Pirates For a Day/Eternity. http://www.fimfiction.net/story/6295/eternity
Maybe it's a bit like the movie "Beaches" in its methods of tugging the heartstrings at the end... but then, "Beaches" was a critically-acclaimed hit at the time and remains the very best in its genre.