Fit your grill with skillet insert and preheat to medium high heat or use a cast iron fry pan.
Brush each side of the red fish fillet with the softened butter. Dredge both sides with Cajun seasoning making sure to have an even coating of spice.
Place the red fish onto the skillet meat side down to start and cook for 5 minutes. Carefully turn over fillet and continue to blacken until the fish is fully cooked.
Remove fish from skillet and set aside to keep warm.
Heat a sauté pan over medium heat and add the olive oil. Add the baby shrimp and red pepper. Cook for 2 minutes and add the wine, lemon juice, lime juice, and green onion. Cook for 3 minutes or until the liquid has reduced by half. Remove from heat, stir in cold butter stirring until the butter has melted.
Place the blackened redfish on plates and pour over the baby shrimp butter.