In a medium bowl, mix the green onions, jalapeno chile, vinegar, Worcestershire sauce, ginger, oil, thyme, allspice, and salt until well mixed. Add snapper and coat well, let sit 5 minutes.
Rub pineapple slices with brown sugar.
Place pineapple and snapper on heated grill over medium heat. Place half of the remaining marinade on snapper. Grill for 5 minutes, turn over spoon remaining marinade on snapper and grill until opaque and pineapple is golden, 5 to 7 minutes.