For the jerk marinade: Combine the brown sugar, lime juice, orange juice, oil, soy sauce, vinegar, allspice, ginger, salt, thyme, cinnamon, nutmeg, garlic, bay leaf, chile and scallion in a food processor and puree. (You can mix in a bowl if you don't have a food processor.)
For the kebabs: Place the chicken in a gallon-size resealable bag. Pour the marinade over the chicken (reserve any extra marinade for later use). Seal the bag and refrigerate 1 hour.
Sprinkle the red onion with salt and pepper. Assemble metal skewers with the chicken, red onion, pineapple and peppers, alternating each ingredient. Brush the kebabs with the remaining marinade.
Preheat a grill to medium-high heat. Spray the grill grates with cooking spray.
Grill the kebabs until the chicken registers 165 degrees F in the center on an instant-read thermometer, about 4 minutes per side. Serve warm.