The Frog Prince
In the Grimm story the frog rescues a golden ball for the princess from the bottom of a well after she promises to be his BFFL but as soon as she has her toy back Little Miss Awful runs off and forgets about the talking frog. Then the frog starts showing up everywhere. It gets creepy. The Princess finally snaps when the frog tries to sneak into her bed at night and she throws the little guy against a wall which triggers his transformation into a prince. SURPRISE!