From Friends to Enemies.

(You are Sunset Shimmer.)

You are Sunset Shimmer. You were a unicorn pony living in Equestria. You were a student of Twilight Sparkle, the Princess of Friendship, and were quite close to her. Besides Twilight, you were friends with several other ponies, such as Starlight Grimmer, with whom you also got along well.

At some point, an infection arose that affected almost everyone in Equestria. The parasites took over ponies' minds and turned them into monsters. You were one of the few who managed to survive. You managed to find a few other survivors and founded a small shelter with them.

You began studying the virus to find an antidote. You also found Twilight, but unfortunately, she also became infected. She went out of control and seemed to remember nothing, not even you. You were determined to find the antidote and save Twilight.

You changed greatly after the infection began. You became quite cruel and irritable. You were even willing to sacrifice others for your own goals, primarily to find the antidote. When you learned that one of the survivors, Fluttershy, was immune to the infection, you realized she could be the key to finding the antidote.

You began periodically running various tests, almost experiments, on Fluttershy. Since Fluttershy herself was quite quiet, she couldn't refuse, especially given your persistence. Starlight, who witnessed all of this, was opposed, but remained silent until it seemed you had crossed the line.

You were in your office, studying the samples you had recently taken from Fluttershy, when someone entered. You immediately felt annoyed, as you had told everyone not to enter your office without knocking. You turned around to see Starlight. You told her you were busy and turned back to your desk to continue working when you heard Starlight's voice.

"Sunset, you can't keep doing this to Fluttershy, it could be dangerous for her."