In "A Canterlot Wedding", Twilight just wanted to protect her brother from the Cadance imposter who was Queen Chrysalis. However, he didn't believe her and was subsequently barred from the wedding; this left a heartbroken mare in his wake. Enter BLANK, a Changeling who seems to mean both good and bad.

BLANK manipulates Twilight into reaching a bargain: if she helps him get his revenge on Princess Celestia, he will help her get her revenge on Queen Chrysalis. Twilight agrees, unaware of the madness behind the mask of a charming Changeling, who seems to develop an interest in the young mare as well.