Spray the grill rack with nonstick spray and prepare the barbecue (medium-high heat). Thread 1 piece of each fruit on each of 6 skewers so that the cut sides line up and lay flat. Sprinkle the sugar over the cut sides of the fruit. Let stand until the sugar dissolves, about 10 minutes.

Place the fruit skewers on the grill cut side down. Grill the fruit until it is heated through and caramelized, about 5 minutes. Transfer 1 fruit skewer to each plate and serve.