Sunset Shimmer is deeply in love with Princess Twilight Sparkle and decides today is the day she's gonna confess! Unfortunately, some others have the same idea.
Turns out that there's an old Equestrian law on the books that any creature can petition to join any princess's harem. Somepony should have warned Twilight, preferably before the former changeling queen showed up on her doorstep.
Twilight's just a little nervous. It has nothing to do with Moondancer taking over the Castle Library. Or Moondancer's smile when she suggested taking over the library. Or anything to do with libraries. It's nothing. Nothing at all.
Twilight's just gotten back to Ponyville after amending her friendships with her oldest friends. She's happy about that, but still there's something nagging at her.
Moondancer has always thought highly of Twilight and was devastated when she left without saying good-bye. When Twilight throws a party for Moondancer and rekindles their friendship, Moondancer decides she wants more.