In the "Odyssey", the shape shifter would be the mighty war goddess, Athena, for she changes her appearance throughout the tale of Odysseus. but (sadly), I have not read the hunger games (yet), so I am not entirely sure who/what you are talking about
She asked if she was bad at any game and a person threw a ball at her and she didn't catch it so she asked why he threw the ball and she became aware at his trick answer.