Combine the sugar and water in a small saucepan over medium heat and cook, stirring until sugar dissolves. Remove from heat and allow to cool. Thinly slice 1/2 of the lemon and 1/2 of the orange. Combine in large pitcher. Juice the other halves of the lemon and orange and add juice and rinds to the pitcher. Add the apple, wine, Grand Marnier and chilled syrup to the pitcher and stir until well mixed. Refrigerate until thoroughly chilled, about 2 hours. Serve straight up or on the rocks.