Season halibut with salt and pepper and drizzle flesh with oil. Grill fish over direct heat, turning occasionally, until center registers 140 degrees on an instant-read thermometer, 10-14 minutes.

Preheat oven to 400 degrees. Season halibut fillets on both sides with salt and pepper. In an ovenproof skillet, heat olive oil over medium heat. Lay in fillets and scatter grapes all around.