is minding Sugar Cube Corner one slow day when an... unusual customer answering to the name Bill Door
arrives. It seems Mr. Door was an old friend of Pinkie's grandfather, and he has an unusual job offer for Pinkie Pie...
Yes, Pinkie Pie becomes the new steed of Discworld
's Death, on a part-time basis at least. But after a bit of a mix-up with the Rite of Ashk'Ente being cast on two planes at once, Pinkie Pie is stuck on the Discworld doing The Duty
, and Death is stuck in Equestria in his guise of Bill Door. On top of all that, it seems Pinkie's antics have inspired a zombie to start a new religion...
Can be found here: http://www.fimfiction.net/story/400/Binky-Pie