Twilight was unable to find the crystal heart and was offered a deal by Sombra. The deal was she would become his apprentice and he wouldn't kill her friends. She excepted the deal and had betrayed her friends to save them. She was never able to tell them why she did it though. She must find a way to tell them and stop Sombra without him knowing.

This is a one shot story. I got this as an idea after listening to a PMV. Hope you guys like it.