The story is by milesprower06 and Ace2401 and can be found here:
http://www.fanfiction.net/s/7210930/1/The_Cupcake_Killer

The story that this is a sequel to is by milesprower06 and can be found here:
http://www.fanfiction.net/s/7132369/1/A_Precious_Rainbow

The background pic is by Lurker-jenova and can be found here:
http://lurker-jenova.deviantart.com/art/Rainbow-Dash-Flightless-272105467

Also, My Little Pony: Friendship is Magic is property of Hasbro, and the canonical characters therein are property of Lauren Faust.

Please leave thoughts and constructive criticism in the comments, and, above all, enjoy! :)