It turns out that Sunset Shimmer's final letters to Princess Celestia before her exile were not filled with resentment or remorse. There might have been a lot more frantic running away involved. But it was definitely not Sunset's fault. At all.
Sunset Shimmer tries to explain to Princess Celestia what happened at her CSGU class reunion. And this time everything is very, definitely, not her fault. At all.
Sunset Shimmer visits the Castle of Friendship, and inadvertently discovers something that Twilight would normally keep hidden under her bed... except that since this is a pony princess we're talking about, it's nothing remotely resembling normal.
