The Conversion Bureau

A My Little Pony Friendship Is Magic fanfic, which has in turn spawned other stories by other people, using the same setting.It is set in on Earth, in the future, where the island of Equestria has suddenly appeared. Earth is not in the greatest shape due to humanity, and the location of Equestria is pushing into Earth territory, with the magic emanating from Equestria being lethal to mankind, and in order to set things right, Princess Celestia needs to send out a powerful wave of magic that will restore the planet, but kill all of humanity. In order to help, Celestia sets up conversion bureaus all around Earth, letting the humans become ponies... though the problem here lies that the converted humans' personalities change.The ponies and the humans have lived together in harmony for centuries. Equestria is an island inhabited entirely by ponies, and some have branched off to live with humans. However, the humans, seeing their bleak world and accepting that they have made too many mistakes in their world to fix, have decided to open facilities to convert humans into ponies and live in peaceful Equestria.