Combine first 5 ingredients in a small microwave-safe bowl. Microwave at HIGH 30 seconds. Add 1/4 teaspoon salt and 1/4 teaspoon pepper; stir to combine. Set aside.
Preheat oven to 425°.
Cut 4 (15 x 24-inch) pieces of parchment paper. Fold in half crosswise. Draw a large heart half on each piece, with the fold of the paper being the center of the heart. Cut out the heart, and open. Place 1 fillet near the fold of each piece of parchment. Squeeze 1 lemon wedge over each fillet. Brush butter mixture evenly over fillets; sprinkle evenly with remaining 1/4 teaspoon salt and remaining 1/4 teaspoon pepper. Starting at the top of the heart, fold edges of parchment, sealing edges with narrow folds. Twist the end tip to secure tightly. Place packets on a baking sheet. Bake at 425° for 12 minutes. Place on plates; cut open. Serve immediately.