We recently caught up with Willow Shields — better known to fans of The Hunger Games as Katniss's kid sister, Prim — at the press line for Catching Fire at Comic-Con. The young actress explained what it was like coming back to the cast, including the surprising reaction she got from onscreen sister Jennifer Lawrence. Shields also let us in on Prim's biggest challenge going into the saga's second chapter. Watch to get the scoop!