The Doctor and Derpy return to Ponyville after their most recent adventure and leave the TARDIS to look around, not realizing that, for the first time in over 900 years, The Doctor forgot to lock the TARDIS.

Fluttershy happens upon the blue telephone box and, curious, walks inside. The TARDIS, not knowing Fluttershy and fearing an attack while her defences are down, opens the console, exposing the Pegasus to the Time Vortex.

When The Doctor and Derpy return, they find a small foal sitting on the TARDIS floor, who calls them Mama and Papa and, after The Doctor has an argument with "Sexy", the TARDIS lands them hundreds of years into the future and not everything in Equestria is as it seems.

Not only that, but The Doctor comes across someone he never thought he would see again.

Set in the Doctor Whooves & Assistant universe by Ponies With Pockets Productions, but well into the future of the series. If you have not watch any episodes of Doctor Whooves & Assistant, i would highly advise you do so before reading.

I take no credit for The Doctor or Derpy or the universe of Whooves & Assistant.